Dehydroborylation of Terminal Alkynes Using Lithium Aminoborohydrides
Abstract
1. Introduction
2. Results and Discussion
3. Materials and Methods
3.1. General Information
3.2. Experimental
3.2.1. General Procedure for the Salt Metathesis Synthesis of Amines-Boranes
3.2.2. General Procedure for the Bicarbonate-Mediated Synthesis of Amines-Boranes
3.2.3. Characterization of Amines-Boranes
- Methylamine-borane (2a): The compound was prepared as described in the salt metathesis procedure and obtained as a white solid (mass = 0.61 g, 68% yield). 1H NMR (300 MHz, CDCl3) δ 3.78 (s, 2H), 2.55 (t, J = 6.3 Hz, 3H), 1.49 (dd, J = 189.1, 92.0 Hz, 3H). 13C NMR (75 MHz, CDCl3) δ 34.6. 11B NMR (96 MHz, CDCl3) δ −18.78 (q, J = 95.1 Hz). Compound characterization is in agreement with previous reports for this compound [15].
- Propylamine-borane (2b): The compound was prepared as described in the bicarbonate-mediated procedure and obtained as a white solid (mass = 1.38 g, 95% yield). 1H NMR (300 MHz, CDCl3) δ 3.81 (s, 2H), 2.75 (p, J = 7.2 Hz, 2H), 1.63 (h, J = 7.4 Hz, 2H), 0.93 (t, J = 7.4 Hz, 3H). 13C NMR (75 MHz, CDCl3) δ 50.4, 22.4, 11.0. 11B NMR (96 MHz, CDCl3) δ −19.84 (q, J = 92.0 Hz). Compound characterization is in agreement with previous reports for this compound [21].
- Cyclohexylamine-borane (2c): The compound was prepared as described in the bicarbonate-mediated procedure and obtained as a white solid (mass = 2.19 g, 97% yield). 1H NMR (300 MHz, CDCl3) δ 3.64 (s, 2H), 2.68 (dqt, J = 14.1, 7.6, 4.0 Hz, 1H), 2.13 (d, J = 10.4 Hz, 2H), 1.80–1.70 (m, 2H), 1.67–1.56 (m, 1H), 1.37–1.07 (m, 5H). 13C NMR (75 MHz, CDCl3) δ 57.0, 32.3, 25.3, 24.5. 11B NMR (96 MHz, CDCl3) δ −0.71–−41.09 (m). Compound characterization is in agreement with previous reports for this compound [21].
- t-Butylamine-borane (2d): The compound was prepared as described in the bicarbonate-mediated procedure and obtained as a white solid (mass = 1.65 g, 95% yield). 1H NMR (300 MHz, CDCl3) δ 3.76 (s, 2H), 1.27 (s, 9H). 13C NMR (75 MHz, CDCl3) δ 53.1, 28.0. 11B NMR (96 MHz, CDCl3) δ −23.25 (q, J = 96.7 Hz). Compound characterization is in agreement with previous reports for this compound [21].
- Dimethylamine-borane (2e): The compound was prepared as described in the salt metathesis procedure and obtained as a white solid (mass = 1.07 g, 91% yield). 1H NMR (300 MHz, CDCl3) δ 4.31 (s, 1H), 2.46 (d, J = 5.8 Hz, 6H), 1.43 (dd, J = 188.2, 91.9 Hz, 3H). 13C NMR (75 MHz, CDCl3) δ 44.2. 11B NMR (96 MHz, CDCl3) δ −14.76 (q, J = 96.7 Hz). Compound characterization is in agreement with previous reports for this compound [15].
- Diethylamine-borane (2f): The compound was prepared as described in the bicarbonate-mediated procedure and obtained as a white solid (mass = 1.65 g, 95% yield). 1H NMR (300 MHz, CDCl3) δ 3.20 (s, 1H), 2.83 (dqt, J = 9.7, 7.3, 3.8 Hz, 4H), 1.25 (t, J = 7.3 Hz, 6H). 13C NMR (75 MHz, CDCl3) δ 48.5, 11.3. 11B NMR (96 MHz, CDCl3) δ −17.07 (q, J = 96.7 Hz). Compound characterization is in agreement with previous reports for this compound [21].
- Piperidine-borane (2g): The compound was prepared as described in the bicarbonate-mediated procedure and obtained as a white solid (mass = 1.96 g, 99% yield). 1H NMR (300 MHz, CDCl3) δ 3.75 (s, 1H), 3.22 (d, J = 13.4 Hz, 2H), 2.59–2.36 (m, 2H), 1.75 (d, J = 10.1 Hz, 3H), 1.51 (ddt, J = 27.9, 14.2, 3.6 Hz, 2H), 1.32 (tdd, J = 16.3, 8.7, 4.6 Hz, 1H). 13C NMR (75 MHz, CDCl3) δ 53.4, 25.4, 22.6. 11B NMR (96 MHz, CDCl3) δ −15.55 (q, J = 96.7 Hz). Compound characterization is in agreement with previous reports for this compound [21].
- Morpholine-borane (2h): The compound was prepared as described in the bicarbonate-mediated procedure and obtained as a white solid (mass = 1.98 g, 98% yield). 1H NMR (300 MHz, CDCl3) δ 4.40 (s, 1H), 3.91 (dd, J = 12.6, 3.3 Hz, 2H), 3.55 (td, J = 12.3, 2.2 Hz, 2H), 3.05 (d, J = 13.7 Hz, 2H), 2.86–2.64 (m, 2H), 2.35–0.65 (m, 3H). 13C NMR (75 MHz, CDCl3) δ 65.6, 51.8. 11B NMR (96 MHz, CDCl3) δ −15.47 (q, J = 98.0, 96.7 Hz). Compound characterization is in agreement with previous reports for this compound [21].
- Diisopropylamine-borane (2i): The compound was prepared as described in the bicarbonate-mediated procedure and obtained as a white solid (mass = 2.12 g, 92% yield). 1H NMR (300 MHz, CDCl3) δ 3.18 (s, 1H), 3.10 (dqd, J = 13.1, 6.5, 3.5 Hz, 2H), 1.15 (t, J = 6.3 Hz, 12H). 13C NMR (75 MHz, CDCl3) δ 51.6, 20.6, 18.6. 11B NMR (96 MHz, CDCl3) δ −21.81 (q, J = 96.7 Hz). Compound characterization is in agreement with previous reports for this compound [27].
- Triethylamine-borane (2j): The compound was prepared as described in the bicarbonate-mediated procedure and obtained as a white solid (mass = 2.16 g, 94% yield). 1H NMR (300 MHz, CDCl3) δ 2.61 (q, J = 7.3 Hz, 6H), 1.02 (t, J = 7.3 Hz, 9H). 13C NMR (75 MHz, CDCl3) δ 51.9, 8.1. 11B NMR (96 MHz, CDCl3) δ −13.81 (q, J = 99.4, 98.0 Hz). Compound characterization is in agreement with previous reports for this compound [21].
3.2.4. General Procedure for the 1 mmol Scale Synthesis of Alkynylborane-Amines
3.2.5. Characterization of Alkynylborane-Amines from Terminal Alkynes
- (Phenylethynyl)borane-dimethylamine (3ae): The compound was prepared as described in the 1 mmol scale procedure and obtained in 2 h as a white solid (mass = 142 mg, 89% yield, 98:2 mono:di ratio); melting point: 74–76 °C (Meltemp). 1H NMR (300 MHz, CDCl3) δ 7.40 (dt, J = 7.5, 1.7 Hz, 2H), 7.35–7.11 (m, 3H), 4.38 (s, 1H), 2.53 (d, J = 5.7 Hz, 6H). 13C NMR (75 MHz, CDCl3) δ 131.2, 127.0, 125.2, 100.0, 42.6. 11B NMR (96 MHz, CDCl3) δ −15.33 (t, J = 100.4 Hz).
- ((4-Methoxyphenyl)ethynyl)borane-dimethylamine (3be): The compound was prepared as described in the 1 mmol scale procedure and obtained in 2 h as a white solid (mass = 183 mg, 97% yield, >99:1 ratio); melting point: 118–120 °C (Meltemp). 1H NMR (300 MHz, CDCl3) δ 7.35 (d, J = 8.7 Hz, 2H), 6.78 (d, J = 8.8 Hz, 2H), 4.46 (s, 1H), 3.76 (s, 3H), 2.56 (d, J = 5.8 Hz, 6H). 13C NMR (75 MHz, CDCl3) δ 158.4, 132.6, 117.5, 113.7, 99.7, 55.3, 42.5. 11B NMR (96 MHz, CDCl3) δ −15.14 (t, J = 93.3 Hz).
- ((4-Fluorophenyl)ethynyl)borane-dimethylamine (3ce): The compound was prepared as described in the 1 mmol scale procedure and obtained in 2 h as a white solid (mass = 174 mg, 98% yield, 99:1 ratio); melting point: 102–104 °C (Meltemp). 1H NMR (300 MHz, CDCl3) δ 7.45–7.33 (m, 2H), 7.00–6.89 (m, 2H), 2.67 (d, J = 5.8 Hz, 6H). 13C NMR (75 MHz, CDCl3) δ 163.1, 159.9, 132.9 (d, J = 7.9 Hz), 121.3 (d, J = 3.0 Hz), 115.9–114.6 (m), 98.9, 42.6. 11B NMR (96 MHz, CDCl3) δ −15.17 (t, J = 99.9 Hz). 19F NMR (282 MHz, CDCl3) δ −114.72–114.96 (m).
- ((4-Ttrifluoromethyl)phenyl)ethynyl)borane-dimethylamine (3de): The compound was prepared as described in the 1 mmol scale procedure and obtained in 2 h as a white solid (mass = 198 mg, 87% yield, 98:2 ratio); white solid, melting point: 80–82 °C (Meltemp). 1H NMR (300 MHz, CDCl3) δ 7.49 (s, 4H), 2.69 (d, J = 5.8 Hz, 6H). 13C NMR (75 MHz, CDCl3) δ 131.3, 129.1, 128.7, 128.2, 125.8, 125.0, 124.9, 122.2, 98.9, 42.6. 11B NMR (96 MHz, CDCl3) δ −15.23 (t, J = 100.6 Hz). 19F NMR (282 MHz, CDCl3) δ −64.14 (s).
- ((2-Methylphenyl)ethynyl)borane-dimethylamine (3ee): The compound was prepared as described in the 1 mmol scale procedure and obtained in 2 h as a clear, colorless liquid (mass = 168 mg, 97% yield, 97:3 ratio); 1H NMR (300 MHz, CDCl3) δ 7.39 (d, J = 7.4 Hz, 1H), 7.13 (dddd, J = 14.8, 9.1, 7.2, 2.3 Hz, 3H), 4.28 (s, 1H), 2.58 (d, J = 5.8 Hz, 6H), 2.45 (s, 3H). 13C NMR (75 MHz, CDCl3) δ 139.3, 131.5, 129.2, 126.9, 125.3, 125.0, 42.5, 21.2. 11B NMR (96 MHz, CDCl3) δ −15.17 (t, J = 99.6 Hz).
- ((3-Methylphenyl)ethynyl)borane-dimethylamine (3fe): The compound was prepared as described in the 1 mmol scale procedure and obtained in 2 h as a clear, colorless liquid (mass = 146 mg, 84% yield, 96:4 ratio); 1H NMR (300 MHz, CDCl3) δ 7.29–7.18 (m, 2H), 7.13 (t, J = 7.5 Hz, 1H), 7.02 (d, J = 7.6 Hz, 1H), 4.39 (s, 1H), 2.55 (d, J = 5.8 Hz, 6H), 2.28 (s, 3H). 13C NMR (75 MHz, CDCl3) δ 131.9, 128.3, 128.0, 127.9, 125.0, 100.2, 42.6, 21.4. 11B NMR (96 MHz, CDCl3) δ −15.40 (t, J = 100.0 Hz).
- ((4-Methylphenyl)ethyny)borane-dimethylamine (3ge): The compound was prepared as described in the 1 mmol scale procedure and obtained in 2 h as a white solid (mass = 149 mg, 86% yield, 99:1 ratio); melting point: 75–77 °C (Meltemp). 1H NMR (300 MHz, CDCl3) δ 7.30 (d, J = 7.9 Hz, 2H), 7.04 (d, J = 7.8 Hz, 2H), 4.44 (s, 1H), 2.52 (d, J = 5.8 Hz, 6H), 2.29 (s, 3H). 13C NMR (75 MHz, CDCl3) δ 136.8, 131.1, 128.9, 122.2, 100.1, 42.5, 21.5. 11B NMR (96 MHz, CDCl3) δ −15.10 (t, J = 99.7 Hz).
- (4-Phenylbut-1-yn-1-yl)borane-dimethylamine (3he): The compound was prepared as described in the 1 mmol scale procedure and obtained in 6 h as a white solid (mass = 140 mg, 75% yield, 88:12 ratio); melting point: 69–72 °C (Meltemp). 1H NMR (300 MHz, CDCl3) δ 7.36–7.08 (m, 5H), 4.14 (s, 1H), 2.83 (t, J = 7.6 Hz, 2H), 2.52 (t, J = 7.8 Hz, 2H), 2.44 (d, J = 5.7 Hz, 6H). 13C NMR (75 MHz, CDCl3) δ 141.3, 128.4, 128.2, 42.2, 36.1, 22.3. 11B NMR (96 MHz, CDCl3) δ −15.35 (t, J = 99.7 Hz).
- (Hexynyl)borane-dimethylamine (3ie): The compound was prepared as described in the 1 mmol scale procedure and obtained in 6 h as a clear, colorless liquid (mass = 114 mg, 82% yield, 94:6 ratio); 1H NMR (300 MHz, CDCl3) δ 2.61 (d, J = 5.8 Hz, 6H), 2.37–2.06 (m, 2H), 1.63–1.28 (m, 4H), 1.02–0.72 (m, 3H). 13C NMR (75 MHz, CDCl3) δ 100.7, 42.2, 31.9, 22.2, 19.8, 13.8. 11B NMR (96 MHz, CDCl3) δ −15.51 (t, J = 98.8 Hz).
- (Decynyl)borane-dimethylamine (3je): The compound was prepared as described in the 1 mmol scale procedure and obtained in 5 h as a clear, colorless liquid (mass = 170 mg, 87% yield, 87:13 ratio); 1H NMR (300 MHz, CDCl3) δ 4.40 (s, 1H), 2.59 (d, J = 5.8 Hz, 6H), 2.21 (t, J = 7.2 Hz, 2H), 1.51 (p, J = 6.9 Hz, 2H), 1.44–1.34 (m, 2H), 1.34–1.17 (m, 8H), 0.87 (t, J = 6.4 Hz, 3H). 13C NMR (75 MHz, CDCl3) δ 100.7, 42.2, 31.9, 29.8, 29.3, 29.3, 29.2, 22.7, 20.1, 14.2. 11B NMR (96 MHz, CDCl3) δ −15.50 (t, J = 100.8 Hz).
- (3,3-Dimethylbut-1-yn-1-yl)borane-dimethylamine (3ke): The compound was prepared as described in the 1 mmol scale procedure and obtained in 4 h as a clear, white solid (mass = 1370 mg, 93% yield, 99:1 ratio);White solid, Melting point: 118–120 °C (Meltemp). 1H NMR (300 MHz, CDCl3) δ 4.03 (s, 1H), 2.61 (d, J = 5.9 Hz, 6H), 1.23 (s, 9H). 13C NMR (75 MHz, CDCl3) δ 109.7, 42.2, 31.9, 28.1. 11B NMR (96 MHz, CDCl3) δ −15.13 (t, J = 98.4 Hz).
- ((Cyclopentyl)ethynyl)borane-dimethylamine (3le): The compound was prepared as described in the 1 mmol scale procedure and obtained in 4 h as a clear, white solid (mass = 135 mg, 89% yield, 99:1 ratio); melting point: 67–70 °C (Meltemp). 1H NMR (300 MHz, CDCl3) δ 4.36 (s, 1H), 2.60 (d, J = 5.7 Hz, 6H), 1.99–1.81 (m, 2H), 1.81–1.64 (m, 2H), 1.64–1.43 (m, 4H). 13C NMR (75 MHz, CDCl3) δ 42.2, 34.6, 31.5, 25.0. 11B NMR (96 MHz, CDCl3) δ −15.47 (t, J = 98.6 Hz).
- ((Trimethylsilyl)ethynyl)borane-dimethylamine (3me): The compound was prepared as described in the 1 mmol scale procedure and obtained in 6 h as a clear, white solid (mass = 129 mg, 83% yield, 98:2 ratio); melting point: 78–80 °C (Meltemp) 1H NMR (300 MHz, CDCl3) δ 2.64 (d, J = 5.8 Hz, 6H), 0.14 (s, 9H). 13C NMR (75 MHz, CDCl3) δ 42.7, 1.1. 11B NMR (96 MHz, CDCl3) δ −15.59 (t, J = 99.9 Hz).
- (3,3,3-Trifluoroprop-1-yn-1-yl)borane-dimethylamine (3ne): The compound was prepared as described in the 1 mmol scale procedure and obtained in 12 h as a clear, pale yellow liquid (mass = 98 mg, 65% yield, 98:2 ratio); 1H NMR (300 MHz, CDCl3) δ 3.82 (s, 1H), 2.63 (d, J = 5.8 Hz, 6H), 1.90 (dd, J = 191.7, 97.4 Hz, 2H). 13C NMR (75 MHz, CDCl3) δ 113.9 (q, J = 254.5 Hz), 42.7. 11B NMR (96 MHz, CDCl3) δ −16.30 (t, J = 102.1 Hz). 19F NMR (282 MHz, CDCl3) δ −50.14.
- ((Cyclohex-1-en-1-yl)ethynyl)borane-dimethylamine (3oe): The compound was prepared as described in the 1 mmol scale procedure and obtained in 5 h as a white solid (mass = 129 mg, 79% yield, 81:19 ratio); melting point: 80–82 °C (Meltemp). 1H NMR (300 MHz, CDCl3) δ 5.98 (tt, J = 3.7, 1.6 Hz, 1H), 4.34 (s, 1H), 2.60 (d, J = 5.9 Hz, 6H), 2.13 (tt, J = 5.7, 2.3 Hz, 2H), 2.05 (h, J = 3.1 Hz, 2H), 1.58 (tdt, J = 10.4, 5.6, 2.7 Hz, 4H). 13C NMR (75 MHz, CDCl3) δ 131.8, 122.0, 102.1, 42.4, 30.1, 25.6, 22.6, 21.8. 11B NMR (96 MHz, CDCl3) δ −15.20 (t, J = 99.7 Hz).
- (Deca-1,5-diyn-1-yl)borane-dimethylamine (3pe): The compound was prepared as described in the 1 mmol scale procedure and obtained in 5 h as a clear, colorless liquid (mass = 157 mg, 82% yield, 85:15 ratio); 1H NMR (300 MHz, CDCl3) δ 4.11 (s, 1H), 2.61 (d, J = 5.8 Hz, 6H), 2.50–2.30 (m, 4H), 2.14 (tt, J = 6.9, 2.0 Hz, 2H), 1.56–1.31 (m, 4H), 0.90 (t, J = 7.1 Hz, 2H). 13C NMR (75 MHz, CDCl3) δ 99.0, 80.8, 79.0, 42.2, 31.2, 22.0, 20.7, 20.0, 18.5, 13.7. 11B NMR (96 MHz, CDCl3) δ −15.39 (t, J = 100.2 Hz).
3.2.6. General Procedure for the Synthesis of Dibromide Substrates
3.2.7. Characterization of Dibromide Substrates
- 1-(2,2-Dibromovinyl)-4-methoxybenzene (6a): The compound was prepared as described in the dibromide synthesis procedure and obtained as a white solid (mass = 1.87 g, 64% yield). 1H NMR (300 MHz, CDCl3) δ 7.56–7.47 (m, 2H), 7.41 (s, 1H), 6.94–6.85 (m, 2H), 3.82 (s, 3H). 13C NMR (75 MHz, CDCl3) δ 159.5, 136.1, 129.8, 127.7, 113.7, 87.2, 55.3. Compound characterization is in agreement with previous reports for this compound [28].
- (4-(2,2-Dibromovinyl)phenyl)(methyl)sulfane (6b): The compound was prepared as described in the dibromide synthesis procedure and obtained as a pale-yellow solid (mass = 1.42 g, 46% yield). 1H NMR (300 MHz, CDCl3) δ 7.50–7.45 (m, 2H), 7.42 (s, 1H), 7.25–7.18 (m, 2H), 2.49 (s, 3H). 13C NMR (75 MHz, CDCl3) δ 139.5, 136.1, 131.6, 128.7, 125.7, 88.9, 15.4. Compound characterization is in agreement with previous reports for this compound [29].
- 2-(2,2-Dibromovinyl)thiophene (6c): The compound was prepared as described in the dibromide synthesis procedure and obtained as a white solid (mass = 2.04 g, 76% yield). 1H NMR (300 MHz, CDCl3) δ 7.66 (d, J = 0.7 Hz, 1H), 7.39 (ddt, J = 5.1, 1.3, 0.6 Hz, 1H), 7.25 (ddt, J = 3.6, 1.2, 0.6 Hz, 1H), 7.04 (ddd, J = 5.2, 3.7, 0.5 Hz, 1H). 13C NMR (75 MHz, CDCl3) δ 137.9, 130.7, 129.9, 127.0, 126.4, 86.9. Compound characterization is in agreement with previous reports for this compound [28].
- 1,1-Dibromo-4-methylpent-1-ene (6d): The compound was prepared as described in the dibromide synthesis procedure and obtained as a pale-yellow liquid (mass = 2.01 g, 83% yield). 1H NMR (400 MHz, CDCl3) δ 6.40 (td, J = 7.3, 2.0 Hz, 1H), 1.99 (td, J = 7.1, 2.0 Hz, 2H), 1.75 (dtd, J = 13.4, 6.7, 2.0 Hz, 1H), 0.93 (dd, J = 6.7, 2.1 Hz, 6H). 13C NMR (101 MHz, CDCl3) δ 137.7, 88.8, 41.7, 27.7, 22.1. Compound characterization is in agreement with previous reports for this compound [30].
3.2.8. General Procedure for the Synthesis of Alkynylborane-Amines from Dibromide Substrates
3.2.9. Characterization of Alkynylborane-Amines from Dibromide Substrates
- ((4-Methoxyphenyl)ethynyl)borane-dimethylamine (7ae): The compound was prepared as described in the alkynylborane-amine from dibromide procedure and obtained in 2 h as a white solid (mass = 168 mg, 89% yield, >99:1 ratio); melting point: 118–120 oC (Meltemp). 1H NMR (300 MHz, CDCl3) δ 7.39–7.32 (m, 2H), 6.82–6.75 (m, 2H), 3.94 (s, 2H), 3.79 (s, 3H), 2.66 (d, J = 5.8 Hz, 6H). 13C NMR (75 MHz, CDCl3) δ 158.20, 132.33, 117.24, 113.46, 99.50, 55.07, 42.30. 11B NMR (96 MHz, CDCl3) δ −15.14 (t, J = 89.1 Hz).
- ((4-(Methylthio)phenyl)ethynyl)borane-dimethylamine (7be): The compound was prepared as described in the alkynylborane-amine from dibromide procedure and obtained in 2 hours as a white solid (mass = 178 mg, 87% yield, >99:1 ratio); melting point: 118–121 °C (Meltemp). 1H NMR (300 MHz, CDCl3) δ 7.40–7.28 (m, 2H), 7.18–7.05 (m, 2H), 3.79 (s, 1H), 2.68 (d, J = 5.8 Hz, 6H), 2.47 (s, 3H). 13C NMR (75 MHz, CDCl3) δ 137.2, 131.6, 125.9, 121.9, 42.6, 15.7. 11B NMR (96 MHz, CDCl3) δ −15.10 (t, J = 98.0 Hz).
- (Thiophen-2-ylethynyl)borane-dimethylamine (7ce): The compound was prepared as described in the alkynylborane-amine from dibromide procedure and obtained in 7 hours as a pale-yellow solid (mass = 155 mg, 94% yield, 94:6 ratio); melting point: 139–142 °C (Meltemp). 1H NMR (300 MHz, CDCl3) δ 7.14–7.07 (m, 2H), 6.91 (dd, J = 5.2, 3.6 Hz, 1H), 3.79 (s, 1H), 2.67 (d, J = 5.8 Hz, 6H). 13C NMR (101 MHz, CDCl3) δ 130.2, 126.6, 125.7, 125.1, 42.5. 11B NMR (96 MHz, CDCl3) δ −15.13 (t, J = 102.1 Hz).
- (4-Methylpent-1-yn-1-yl)borane-dimethylamine (7de): The compound was prepared as described in the alkynylborane-amine from dibromide procedure and obtained in 4 hours as a clear, colorless liquid (mass = 123 mg, 89% yield, 93:7 ratio); 1H NMR (300 MHz, CDCl3) δ 3.82 (s, 1H), 2.62 (d, J = 5.8 Hz, 6H), 2.11 (dt, J = 6.7, 1.9 Hz, 2H), 1.85–1.70 (m, 1H), 0.97 (d, J = 6.6 Hz, 6H). 13C NMR (101 MHz, CDCl3) δ 42.2, 29.3, 28.6, 22.1. 11B NMR (96 MHz, CDCl3) δ −15.26 (t, J = 99.4 Hz).
4. Conclusions
Supplementary Materials
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
Sample Availability
References
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Entry | Condition | Solvent | Amine-Borane | Products | Ratio b | Conversion c |
---|---|---|---|---|---|---|
1 | rt, 24 h | Et2O | 2e | 3ae/4ae | 85:15 | 95% |
2 | rt, 24 h | THF | 2e | 3ae/4ae | 73:27 | 51% |
3 | rt, 24 h | DME | 2e | 3ae/4ae | 80:20 | 30% |
4 | rt, 24 h | DCM | 2e | 3ae/4ae | 87:13 | 80% |
5 | rt, 24 h | toluene | 2e | 3ae/4ae | 100:0 | 79% |
6 | rt, 24 h | pentane | 2e | 3ae/4ae | 99:1 | 92% |
7 | rt, 24 h | Et3N | 2e | 3ae/4ae | 85:15 | 80% |
8 | reflux, 2 h | pentane | 2e | 3ae/4ae | 99:1 | 97% |
9 | reflux, 2 h | pentane | 2a | 3aa/4aa | - | trace |
10 | reflux, 2 h | pentane | 2b | 3ab/4ab | - | trace |
11 | reflux, 2 h | pentane | 2c | 3ac/4ac | 99:1 | 16% |
12 | reflux, 2 h | pentane | 2d | 3ad/4ad | 92:8 | 82% |
13 | reflux, 2 h | pentane | 2f | 3af/4af | 99:1 | 66% |
14 | reflux, 2 h | pentane | 2g | 3ag/4ag | 99:1 | 83% |
15 | reflux, 2 h | pentane | 2h | 3ah/4ah | - | trace |
16 | reflux, 2 h | pentane | 2i | 3ai/4ai | 93:7 | 14% |
17 | reflux, 2 h | pentane | 2j | 3aj/4aj | - | 0% |
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Ramachandran, P.V.; Hamann, H.J. Dehydroborylation of Terminal Alkynes Using Lithium Aminoborohydrides. Molecules 2023, 28, 3433. https://doi.org/10.3390/molecules28083433
Ramachandran PV, Hamann HJ. Dehydroborylation of Terminal Alkynes Using Lithium Aminoborohydrides. Molecules. 2023; 28(8):3433. https://doi.org/10.3390/molecules28083433
Chicago/Turabian StyleRamachandran, P. Veeraraghavan, and Henry J. Hamann. 2023. "Dehydroborylation of Terminal Alkynes Using Lithium Aminoborohydrides" Molecules 28, no. 8: 3433. https://doi.org/10.3390/molecules28083433
APA StyleRamachandran, P. V., & Hamann, H. J. (2023). Dehydroborylation of Terminal Alkynes Using Lithium Aminoborohydrides. Molecules, 28(8), 3433. https://doi.org/10.3390/molecules28083433