A Well-Defined {[(PhCH2O)2P(CH3)2CHNCH(CH3)2]2PdCl2} Complex Catalyzed Hiyama Coupling of Aryl Bromides with Arylsilanes

A palladium (II) complex {[(PhCH2O)2P(CH3)2CHNCH(CH3)2]2PdCl2} catalyzed Hiyama cross-coupling reaction between aryl bromides and arylsilanes has been developed. The substituted biaryls were produced in moderate to high yields, regardless of electron-withdrawing or electron-donating.


Optimization of the Hiyama Reaction Condition
The catalyst PdCl2L2, which was inert to air and moisture, was composed of Na2PdCl4 with 2 equiv of the ligand L in THF at room temperature ( Figure 1). The X-ray crystal structure of PdCl2L2 was shown as reported in [23]. The model reaction of bromobenzene with phenyltrimethoxysilane was initiated to optimize the cross-coupling conditions. Solvents used in the reaction were environmentally friendly and cheap and it avoid the troublesome solvents (NMP, DMF, etc.) that were conventionally applied in similar Hiyama reactions [14]. Results showed that no cross-coupled product was obtained when only H2O was used as solvent ( Table 1, entry 1). However, it was exciting that a low yield (36%) was obtained in PEG solvent (Table 1, entry 2). Inspired by this, we explored different proportions of PEG and H2O (Table 1, entries [3][4][5], and it was discovered that PEG:H2O = 1:1 (volume ratio) was the efficient reaction system in this reaction (Table 1, entry 4) while the mixed solvent CH3CH2OH and H2O was not suitable for this reaction (Table 1, entry 6). Consequently, PEG:H2O = 1:1 (volume ratio) was chosen as the best solvent. To the best our knowledge, the base TBAF•3H2O played a key role in this reaction because TBAF•3H2O may show the function of the activation of arylsilane [24]. In order to avoid the use of TBAF•3H2O, we started to investigate a variety of inorganic salt base which should show the capability to favor the removal of silicon groups. Intriguingly, it gave a high yield of biphenyls (85%) when NaOH was applied as the base (Table 1, entry 7). Furthermore, the reaction did not proceed well when carried out with other base such as KOH, Et3N, Na2CO3, K3PO4 and NaOAc•3H2O (Table 1, entries [8][9][10][11][12]. According to the above results, PEG:H2O = 1:1 (volume ratio), as the solvent, and NaOH as the base gave the best results. Since this catalytic system was not sensitive to oxygen, the reactions were carried out under air atmosphere without the protection of nitrogen.

Optimization of the Hiyama Reaction Condition
The catalyst PdCl 2 L 2 , which was inert to air and moisture, was composed of Na 2 PdCl 4 with 2 equiv of the ligand L in THF at room temperature ( Figure 1). The X-ray crystal structure of PdCl 2 L 2 was shown as reported in [23]. The model reaction of bromobenzene with phenyltrimethoxysilane was initiated to optimize the cross-coupling conditions. Solvents used in the reaction were environmentally friendly and cheap and it avoid the troublesome solvents (NMP, DMF, etc.) that were conventionally applied in similar Hiyama reactions [14]. Results showed that no cross-coupled product was obtained when only H 2 O was used as solvent (Table 1, entry 1). However, it was exciting that a low yield (36%) was obtained in PEG solvent (  [3][4][5], and it was discovered that PEG:H 2 O = 1:1 (volume ratio) was the efficient reaction system in this reaction (  [24]. In order to avoid the use of TBAF‚3H 2 O, we started to investigate a variety of inorganic salt base which should show the capability to favor the removal of silicon groups. Intriguingly, it gave a high yield of biphenyls (85%) when NaOH was applied as the base (Table 1, entry 7). Furthermore, the reaction did not proceed well when carried out with other base such as KOH, Et 3 N, Na 2 CO 3 , K 3 PO 4 and NaOAc‚3H 2 O (Table 1, entries [8][9][10][11][12]. According to the above results, PEG:H 2 O = 1:1 (volume ratio), as the solvent, and NaOH as the base gave the best results. Since this catalytic system was not sensitive to oxygen, the reactions were carried out under air atmosphere without the protection of nitrogen.

Optimization of the Hiyama Reaction Condition
The catalyst PdCl2L2, which was inert to air and moisture, was composed of Na2PdCl4 with 2 equiv of the ligand L in THF at room temperature ( Figure 1). The X-ray crystal structure of PdCl2L2 was shown as reported in [23]. The model reaction of bromobenzene with phenyltrimethoxysilane was initiated to optimize the cross-coupling conditions. Solvents used in the reaction were environmentally friendly and cheap and it avoid the troublesome solvents (NMP, DMF, etc.) that were conventionally applied in similar Hiyama reactions [14]. Results showed that no cross-coupled product was obtained when only H2O was used as solvent (Table 1, entry 1). However, it was exciting that a low yield (36%) was obtained in PEG solvent (Table 1, entry 2). Inspired by this, we explored different proportions of PEG and H2O (Table 1, entries 3-5), and it was discovered that PEG:H2O = 1:1 (volume ratio) was the efficient reaction system in this reaction (Table 1, entry 4) while the mixed solvent CH3CH2OH and H2O was not suitable for this reaction (Table 1, entry 6). Consequently, PEG:H2O = 1:1 (volume ratio) was chosen as the best solvent. To the best our knowledge, the base TBAF•3H2O played a key role in this reaction because TBAF•3H2O may show the function of the activation of arylsilane [24]. In order to avoid the use of TBAF•3H2O, we started to investigate a variety of inorganic salt base which should show the capability to favor the removal of silicon groups. Intriguingly, it gave a high yield of biphenyls (85%) when NaOH was applied as the base (Table 1, entry 7). Furthermore, the reaction did not proceed well when carried out with other base such as KOH, Et3N, Na2CO3, K3PO4 and NaOAc•3H2O (Table 1, entries [8][9][10][11][12]. According to the above results, PEG:H2O = 1:1 (volume ratio), as the solvent, and NaOH as the base gave the best results. Since this catalytic system was not sensitive to oxygen, the reactions were carried out under air atmosphere without the protection of nitrogen.

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl 2 L 2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100˝C (Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C (Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h ( Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h ( Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields (Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica,

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields ( Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields ( Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields ( Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields ( Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Scope of the Substrates
The optimized reaction conditions were used in the Hiyama coupling reaction of various aryl bromides and arylsilanes with PdCl2L2 as a catalyst. The results were shown in Table 2. As expected, activated aryl bromide was smoothly converted into the corresponding products in 92% yields and 85% yields ( Table 2, entries 2, 5). However, the electron donating group of aryl bromide would slightly decrease the reaction efficiency (Table 2, entries 3, 6). We also examined the electron donating group of arylsilane base on the resulting yields of the reactions. Electron donating group of arylsilane could be afforded biphenyl compounds at a higher temperature for 100 °C ( Table 2, entries 4-8) but with lower yields. If aryl bromide and arylsilane both contained an electron donating group, the biphenyl yield clearly declined (Table 2, entry 6). Importantly, 1-bromonaphthalene was also applicable to these reaction conditions in moderate to good yield (Table 2, entry 7). The reaction system was also sufficiently stable for halogenated heterocyclic, so that 2-bromothiophene could be coupled with good efficiency ( Table 2, entry 8).

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl2L2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na2PdCl4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The

Reagents and Equipment
NMR spectra were recorded using 400 MHz in DMSO-d 6 solutions at room temperature (tetramethylsilane (TMS) was used as an internal standard) on a Bruker Avance III spectrometer (Billerica, MA, USA, see Supplementary Materials). All chemicals employed in the reaction were analytical grade, obtained commercially from Aldrich or Alfa Aesar and were used as received without any prior purification.

Synthesis of the Catalyst
The palladium complex PdCl 2 L 2 was prepared using a method previously reported elsewhere [21]. A solution of 1 mmol (0.345 g) was added dropwise to a suspension of 0.5 mmol Na 2 PdCl 4 (0.147 g) in THF (20.0 mL) and the reaction mixture was stirred at ambient temperature for 4 h (Figure 1). The volume was reduced to 5.0 mL and diethyl ether was added to precipitate a yellow powder which was then filtered off and washed with diethyl ether. The complex PdCl 2 L 2 was obtained in 92% yield.

General Procedure for the Synthesis
A mixture of aryl bromide (1.0 mmol), arylsilane (1.2 mmol), NaOH (3.0 mmol), 4.0 mL solvent, PEG:H 2 O = 1:1 (volume ratio) and catalyst (0.02 mmol) was stirred at 80-100˝C for 2 h under air. The reaction was quenched with brine (15 mL) and extracted three times with ethyl acetate (3ˆ10 mL). The organic phase was dried with MgSO 4 for 4 h, filtered and concentrated under reduced pressure using a rotary evaporator. The crude products were re-crystallized by dichloromethane (2 mL) at´10˝C for 24 h. Filtered and dried, the purified products were identified by 1 H-NMR and 13 C-NMR spectroscopy.

Conclusions
In conclusion, complex PdCl 2 L 2 was demonstrated to be a highly active catalyst for the Hiyama coupling reaction of a range of aryl bromides with arylsilanes, affording the coupling products with moderate to high yields. This method is consistent with the concept of green chemistry, and further studies on the applicability of this catalyst system in other coupling reactions such as Sonogashira and amination are currently under investigation in our laboratory.