Syntheses of inhibitors
The syntheses of compounds
1,
2,
8-21, and
25 are described in [
17].
Method A: Introduction of the double bond. To substances 29, 30 or 32 (1 equiv.) and TMDM (N,N,N’,N’-tetramethyldiaminomethane, 20 equiv.), acetic anhydride (20 equiv.) was added slowly. The mixture was heated under reflux at 85 °C. The reaction is followed by 1H-NMR spectroscopy. After completion of the reaction the mixture was cooled to room temperature and saturated K2CO3 solution was added until gas evolution stopped. The product was extracted with Et2O, washed with water and brine and dried with Na2SO4. The solvent was removed in vacuo and the product purified by column chromatography.
Method B: Syntheses of bromoacetamides. Bromoacetyl bromide (1 equiv.) in absolute CH2Cl2 was cooled to -30 °C. Amine (1 equiv.) and triethylamine (1 equiv.) in absolute CH2Cl2 were added dropwise. After the addition, the reaction mixture was warmed up to room temperature and stirred for 1-2 h further. The solvent was removed in vacuo, the product was dissolved in acetone and filtered off. The bromoacetamides were used directly without further purification.
Method C: Coupling of the bromoacetamide or bromoacetic acid ester with 1-(3-Fluoro-4-hydroxyphenyl)butan-1-one. 1-(3-Fluoro-4-hydroxyphenyl)butan-1-one (1 equiv.), K2CO3 (1.5 equiv.) and KI (0.1 equiv.) were refluxed in dry acetone for 1 h. Bromoacetamide (method B) or bromoacetic acid ester (2 equiv.) were added and the mixture heated to reflux for a further 4 h. The mixture was cooled to room temperature, filtered and the solvent was removed in vacuo. The product was dissolved in Et2O, washed with brine, KOH solution (5%) and water, and dried with Na2SO4. The solvent was removed in vacuo and the product was purified by column chromatography.
Tert-butyl 2-(2-fluoro-4-(2-methylenebutanoyl)phenoxy)acetate (3). Method A: Tert-butyl-2-(4-butyryl-2-fluorophenoxy)acetate (29, 558 mg, 1.89 mmol), TMDM (5.14 mL, 37.7 mmol), acetic anhydride (3.56 mL, 37.7 mmol). Rf: 0.73 (cyclohexane/ethyl acetate: 1/1); yield 180 mg (0.58 mmol, 31 %); yellow oil; LOOP-ESI-MS: calcd. for C16H21FO4 308.35, found [M+H]+ 309.2; LC-MS: Rt = 38.2 min, purity 100 %; 1H-NMR: δ 1.09 (t, 3H, 3J = 7.5 Hz, CH2CH2CH3), 1.47 (s, 9H, Cq(CH3)3), 2.45 (q, 2H, 3J = 7.4 Hz, CH2CH2CH3), 4.64 (s, 2H, OCH2C=O), 5.50 (s, 1H, Cq=CH2), 5.74 (s, 1H, Cq=CH2), 6.88 (dd, 1H, J = 8.4 Hz, CHarom.), 7.54–7.59 (m, 2H, CHarom.); 13C-NMR: δ 12.30 (CqCH2CH3), 25.51 (CqCH2CH3), 28.01 (Cq(CH3)3), 66.48 (OCH2C=O), 82.95 (Cq(CH3)3), 114.09 (CHarom.), 117.98 (CHarom.), 122.82 (Cq=CH2), 126.52 (CHarom.), 131.64 (CqC=O), 149.39 (Cq=CH2), 150.58 (CqF or CqOCH2C=O), 153.06 (CqF or CqOCH2C=O), 166.96 (OCH2C=O), 196.12 (CqC=O).
2-(2-fluoro-4-(2-methylenebutanoyl)phenoxy)acetic acid (4): 1-(3-fluoro-4-hydroxyphenyl)butan-1-one. 2-Fluoroanisole (4.00 g, 31.7 mmol) and butyric acid chloride (5.07 g, 47.6 mmol) were dissolved under a N2 atmosphere in absolute CH2Cl2 (50 mL) and the mixture was cooled to 0-10 °C. AlCl3 (6.35 g, 47.6 mmol) was added within 30 minutes, and the mixture was stirred for 2-3 h. An additional amount of AlCl3 (6.35 g, 47.6 mmol) was added, and the mixture was heated under reflux for 2 h. The mixture was poured on ice and acidified with concentrated HCl to pH 1. Tartaric acid was added for complexation of aluminum until the solution was clear. The solution was extracted with Et2O and the organic layer was washed with KOH solution (10%) and brine. The organic layer was dried with Na2SO4 and solvent was removed in vacuo. Yield 4.97 g (27.3 mmol, 86 %); white solid; mp. 91 °C (water); 1H-NMR: δ 0.98 (t, 3H, 3J = 7.3 Hz, CH2CH2CH3), 1.74 (sext, 2H, 3J = 7.3 Hz, CH2CH2CH3), 2.87 (t, 2H, 3J = 7.3 Hz, CH2CH2CH3), 6.04 (bs, 1H, OH), 7.04 (dd, 1H, J = 8.5 Hz, CHarom.), 7.67–7.73 (m, 2H, CHarom.).
Ethyl-2-(4-butyryl-2-fluorophenoxy)acetate. 1-(3-Fluoro-4-hydroxyphenyl)butan-1-one (2.00 g, 11.0 mmol), bromoacetic acid ethyl ester (3.67 g, 22.0 mmol), K2CO3 (2.28 g, 16.5 mmol) and KI (183 mg, 1.10 mmol) were refluxed in dry acetone for 5-6 h. The reaction mixture was cooled to room temperature and filtered off. The solvent was removed in vacuo and the product was extracted with Et2O, washed with NaOH solution (10%), water and brine, dried with Na2SO4, and the solvent was removed in vacuo. Yield 2.30 g (8.60 mmol, 78%); white solid; mp. 79-80 °C (Et2O). 1H-NMR (DMSO-d6): δ 0.90 (t, 3H, 3J = 7.5 Hz, CH2CH2CH3), 1.20 (t, 3H, 3J = 7.2 Hz, OCH2CH3), 1.60 (sext, 2H, 3J = 7.3 Hz, CH2CH2CH3), 2.93 (t, 2H, 3J = 7.1 Hz, CH2CH2CH3), 4.17 (q, 2H, 3J = 7.1 Hz, OCH2CH3), 4.99 (s, 2H, OCH2C=O), 7.20 (dd, 1H, J = 8.5, CHarom.), 7.74–7.78 (m, 2H, CHarom.).
2-(2-fluoro-4-(2-methylenebutanoyl)phenoxy)acetic acid (4). Ethyl-2-(4-butyryl-2-fluorophenoxy)-acetate (2.11 g, 7.87 mmol), formaldehyde solution (40%, 1.08 mL, 15.7 mmol) and K2CO3 (2.17 g, 15.7 mmol, dissolved in water) were refluxed in ethanol for 24 h. The reaction mixture was cooled to room temperature, acidified with concentrated HCl to pH 1 and the product was extracted with Et2O. The solvent was removed in vacuo. Yield 556 mg (2.20 mmol, 28%); white solid; mp 99-101 °C (Et2O); LOOP-ESI-MS: calcd. for C13H13FO4 252.24, found [M+H]+ 253.1; LC-MS: Rt = 23.8 min, purity 100 %; 1H-NMR: δ 1.10 (t, 3H, 3J = 7.5 Hz, CqCH2CH3). 2.46 (q, 2H, 3J = 7.4 Hz, CqCH2CH3), 4.81 (s, 2H, OCH2C=O), 5.52 (s, 1H, Cq=CH2), 5.78 (s, 1H, Cq=CH2), 6.95 (dd, 1H, J = 8.4 Hz, CHarom.), 7.56–7.60 (m, 2H, CHarom.); 13C-NMR: δ 12.30 (CqCH2CH3), 25.44 (CqCH2CH3), 65.65 (OCH2C=O), 114.50 (CHarom.), 118.19 (CHarom.), 123.35 (Cq=CH2), 126.59 (CHarom.), 132.35 (CqC=O), 148.87 (Cq=CH2), 149.33 (CqF or CqOCH2C=O), 153.11 (CqF or CqOCH2C=O), 172.29 (OCH2C=O), 196.16 (CqC=O).
N-tert-butyl-2-(2-fluoro-4-(2-methylenebutanoyl)phenoxy)acetamide (5). 2-(2-Fluoro-4-(2-methylene-butanoyl)phenoxy)acetic acid (4, 767 mg, 3.00 mmol) and N-hydroxysuccinimide (336 mg, 3.00 mmol) were dissolved under a N2 atmosphere in absolute CH2Cl2 (10 mL). Dicyclohexylcarbodiimide (DCC) (619 mg, 3.00 mmol) was added in small portions and the mixture was stirred overnight. The mixture was filtered into a flask with tert-butylamine (219 mg, 3.00 mmol) in CH2Cl2 (10 mL), stirred for 3 h at room temperature and filtered. The reaction mixture was washed with brine and KOH solution (5%), dried with Na2SO4 and the solvent was removed in vacuo. The product was purified by column chromatography. Rf: 0.43 (cyclohexane/ethyl acetate: 2/1); yield 314 mg (1.02 mmol, 34 %); white solid; mp 85 °C (cyclohexane/ethyl acetate); LOOP-ESI-MS: calcd. for C17H22FNO3 307.37, found [M+H]+ 308.4; LC-MS: Rt = 18.0 min, purity 100 %; 1H-NMR: δ 1.10 (t, 3H, 3J = 7.5 Hz, CqCH2CH3), 1.40 (s, 9H, Cq(CH3)3), 2.46 (q, 2H, 3J = 7.4 Hz, CqCH2CH3), 4.46 (s, 2H, OCH2C=O), 5.51 (s, 1H, Cq=CH2), 5.78 (s, 1H, Cq=CH2), 6.43 (bs, 1H, NH), 6.96 (dd, 1H, J = 8.2 Hz, CHarom.), 7.56–7.62 (m, 2H, CHarom.); 13C-NMR: δ 12.30 (CqCH2CH3), 25.45 (CqCH2CH3), 28.71 (Cq(CH3)3), 51.46 (Cq(CH3)3), 68.50 (OCH2C=O), 114.05 (CHarom.), 117.73 (CHarom.), 123.23 (Cq=CH2), 126.92 (CHarom.), 132.23 (CqC=O), 146.73 Cq=CH2), 148.87 (CqF or CqOCH2C=O), 149.35 (CqF or CqOCH2C=O), 165.95 (OCH2C=O), 196.01 (CqC=O).
N-butyl-2-(2-fluoro-4-(2-methylenebutanoyl)phenoxy)acetamide (6). Method A: N-butyl-2-(4-butyryl-2-fluorophenoxy)acetamide (30) (105 mg, 0.36 mmol), TMDM (0.97 mL, 7.11 mmol), acetic anhydride (0.67 mL, 7.11 mmol). Rf: 0.59 (cyclohexane/ethyl acetate: 1/2); yield 55.5 mg (0.18 mmol, 51 %); white solid; mp 73 °C (cyclohexane/ethyl acetate); LOOP-ESI-MS: calcd. for C17H22FNO3 307.37; found [M+H]+ 308.4; LC-MS: Rt = 15.8 min, purity 100 %; 1H-NMR: δ 0.93 (t, 3H, 3J = 7.4 Hz, NHCH2CH2CH2CH3), 1.11 (t, 3H, 3J = 7.4 Hz, CqCH2CH3), 1.36 (sext, 2H, 3J = 7.4 Hz, NHCH2CH2CH2CH3), 1.53 (sext, 3J = 7.3 Hz, NHCH2CH2CH2CH3), 2.46 (q, 2H, 3J = 7.5 Hz, CqCH2CH3), 3.37 (q, 2H, 3J = 6.7 Hz, NHCH2CH2CH2CH3), 4.57 (s, 2H, OCH2C=O), 5.51 (s, Cq=CH2), 5.78 (s, Cq=CH2), 6.60 (s, 1H, NH), 6.96 (dd, 1H, J = 8.1 Hz, CHarom.), 7.57–7.62 (m, 2H, CHarom.); 13C-NMR: δ 12.31 (CqCH2CH3), 13.69 (NHCH2CH2CH2CH3), 20.00 (NHCH2CH2CH2CH3), 25.45 (CqCH2CH3), 31.53 (NHCH2CH2CH2CH3), 38.90 (NHCH2CH2CH2CH3), 68.21 (OCH2C=O), 113.90 (CHarom.), 117.77 (CHarom.), 123.22 (Cq=CH2), 126.92 (CHarom.), 149 (CqF or CqOCH2C=O), 166.77 (OCH2C=O).
Methyl-2-(2-(2-fluoro-4-(2-methylenebutanoyl)phenoxy)acetamido)-3-methylpentanoate (
7). Method A: Methyl-2-(2-(4-butyryl-2-fluorophenoxy)acetamido)-3-methylpentanoate (
32, 58.0 mg, 0.16 mmol), TMDM (0.43 mL, 3.16 mmol), acetic anhydride (0.30 mL, 3.16 mmol). R
f: 0.75 (cyclohexane/ethyl acetate: 1/1); yield 41.5 mg (0.11 mmol, 68 %); colorless oil; LOOP-ESI-MS: calcd. for C
20H
26FNO
5 379.43; found [M+H]
+ 380.4; LC-MS: R
t = 18.9 min, purity 100 %; [α]
: 61.1 (CHCl
3, c = 0.1).
1H-NMR: δ 0.90–0.94 (m, 6H, Ile-CH
2C
H3 and Ile-CHC
H3), 1.11 (t, 3H,
3J = 7.5 Hz, C
qCH
2C
H3), 1.14–1.22 (m, 2H, Ile-C
H2CH
3), 1.40–1.48 (m, 1H, Ile-C=O), 1.93–1.99 (m, 1H, Ile-C
HCH
3), 2.47 (t, 2H,
3J = 7.3 Hz, C
qC
H2CH
3), 3.74 (s, 3H, OC
H3), 4.62 (s, 2H, OC
H2C=O), 5.51 (s, C
q=C
H2), 5.78 (s, C
q=C
H2), 6.98 (dd, 1H,
3J = 8.2 Hz, C
Harom.), 7.08 (d, 1H,
J = 8.5 Hz, N
H), 7.57–7.63 (m, 2H, C
Harom.);
13C-NMR: δ 11.51 (Ile-CH
2CH
3 or Ile-CH
CH
3), 12.31 (C
qCH
2CH
3), 15.50 (Ile-CH
2CH
3 or Ile-CH
CH
3), 25.08 (C
qCH
2CH
3 or Ile-
CHC=O), 25.43 (C
qCH
2CH
3 or Ile-N
CHC=O), 37.79 (Ile-
CHCH
3), 52.23 (O
CH
3), 68.32 (O
CH
2C=O), 114.25 (
CH
arom.), 117.86 (
CH
arom.), 123.26 (C
q=
CH
2), 126.81 (
CH
arom.), 132.46 (
CqC=O), 149.37 (
CqOCH
2C=O), 150.66 (
Cq=CH
2), 153.14 (
CqF), 166.83 (OCH
2C=O), 171.68 (
CqOCH
3), 195.98 (C
qC=O).
2-{2-[2,3-Dichloro-4-(2-methylene-butyryl)-phenoxy]acetylamino}pentanedioic acid (
22). Compound
22 was synthesized according to [
17] starting from etacrynic acid (240 mg, 0.79 mmol),
N-hydroxy-succinimide (91 mg, 0.79 mmol), DCC (163 mg, 0.79 mmol) in THF. The solvent was removed and a solution of glutamic acid (116 mg, 0.79 mmol) and KOH (133 mg, 2.37 mmol) in water was added. After stirring 7 days at room temperature the mixture was acidified with conc. HCl and extracted with dichloromethane. The crude product, which still contained etacrynic acid, was suspended in hot benzene and filtered. The solid residue yielded the pure amide as a white powder. Yield: 55 mg (0.127 mmol, 16 %).
1H-NMR (
d4-MeOH): δ = 1.14 (t, 3H,
3J = 8.0 Hz, CH
2C
H3), 2.05 (m, 1H), 2.27 (m, 1H), 2.38 – 2.47 (m, 4H, 2 CH
2), 4.57 (m, 1H, NHC
H), 4.75 (s, 2H, OCH
2CO), 5.60 (s, 1H, C=CH), 6.02 (s, 1H, C=CH), 7.10 (d, 1H,
3J = 8.0 Hz, Ar-H), 7.24 (d, 1H,
3J = 8.0 Hz, Ar-H); LC-MS (negative mode):
m/z: 431.2 (100) [M-H]
-, R
t = 2.3 min.
6-{2-[2,3-Dichloro-4-(2-methylene-butyryl)-phenoxy]acetylamino}-hexanoic acid (
23). Compound
23 was synthesized according to [
17] starting from etacrynic acid (201 mg, 0.66 mmol),
N-hydroxy-succinimide (76 mg, 0.66 mmol), DCC (137 mg, 0.66 mmol) in dichloromethane (20 mL). The solvent was removed and the residue taken up in THF. This solution was added to a solution of 6-amino-hexanoic acid (130 mg, 0.99 mmol) and KOH (111 mg, 1.98 mmol) in water (10 mL). After 3 days stirring at room temperature the mixture was acidified with conc. HCl and extracted with dichloromethane. After removal of the organic solvent the crude product yielded a yellow oil which was purified by column chromatography (MeOH/CHCl
3 10:2). Product: colourless oil, which solidified to a white solid. Yield: 93 mg (0.22 mmol, 34 %);
1H-NMR (
d4-MeOH): δ = 1.14 (t, 3H,
3J = 8.0 Hz, CH
2C
H3), 1.33 – 1.40 (m, 2H, CH
2), 1.53 – 1.66 (m, 4H, 2 CH
2), 2.28 (t, 2H,
3J = 8.0 Hz, CH
2), 2.44 (q, 2H,
3J = 8.0 Hz, C
H2CH
3), 3.30 (m, 2H, NHC
H2), 4.68 (s, 2H, OCH
2CO), 5.59 (s, 1H, C=CH), 6.03 (s, 1H, C=CH), 7.07 (d, 1H,
3J = 8.0 Hz, Ar-H), 7.24 (d, 1H,
3J = 8.0 Hz, Ar-H);
13C-NMR (
d4-MeOH): δ = 13.0 (CH
3), 24.5 (CH
2), 25.7 (CH
2), 27.4 (CH
2), 30.1 (CH
2), 34.9 (CH
2), 40.0 (CH
2), 69.5 (O
CH
2CO), 112.9 (Ar-CH), 124.0 (Ar-qC), 128.5 (Ar-CH), 129.9 (C=
CH
2), 131.8 (Ar-qC), 135.0 (Ar-qC), 151.7 (qC,
C=CH
2), 156.9 (Ar-qC), 169.7 (qC, NHCONH), 177.6 (qC, COOH), 197.3 (qC, C=O); LC-MS:
m/z: 418.0 (15), R
t = 0.5 min.
5-(2-Oxo-hexahydro-thieno[3,4-d]imidazol-4-yl)pentanoic acid (6-{2-[2,3-dichloro-4-(2-methylene-butyryl)-phenoxy]acetylamino}-hexyl)-amide (24)
(A) Coupling of Boc-diaminohexane and D-biotin: Boc-diaminohexane (443 mg, 2.05 mmol) and D-biotin (500 mg, 2.05 mmol) were suspended in absolute DMF (45 mL) and cooled to 0 °C. DPPA (620 mg, 2.25 mmol) and triethylamine (229 mg, 2.25 mmol) were added and the mixture was stirred at 4 °C for 8 days. Dichloromethane (25 mL) was added and the organic phase was washed twice with citric acid (10%). Upon addition of water to the organic phase the amide precipitated as a white solid which was filtered off.
(B) Removal of the Boc-protecting group: The solid obtained in step (A) was suspended in dichloromethane (9 mL) and treated with TFA (3 mL) at 0 °C. Excess TFA was repeatedly removed in vacuo. For better evaporation dichloromethane was added to the residue. Quantitative removal of the protecting group was verified by 1H-NMR.
(C) Amide coupling to etacrynic acid: Biotin-(6-amino)-hexylamide (TFA-salt) (175 mg, 0.383 mmol), triethylamine (39 mg, 0.383 mmol) and etacrynic acid (232 mg, 0.767 mmol) were dissolved in DMF (2 mL). EEDQ (190 mg, 0.767 mmol) was added and the mixture was stirred at room temperature for 14 days. Ethyl acetate (50 mL) was added. Treatment of the organic phase with Na2CO3-solution (2%, 25 mL) yielded the desired product as a white precipitate which was filtered off. Overall yield: 62 mg (0.0988 mmol) as a white solid; 1H-NMR (DMSO-d6): δ = 1.07 (t, 3H, 3J = 7.4 Hz, CH2CH3), 1.23 – 1.57 (m, 14H, CH2), 2.03 (t, 2H, 3J = 7.2 Hz, CH2), 2.36 (q, 2H, 3J = 7.4 Hz, CH2CH3), 2.56 (d, 1H, 3J = 12.3 Hz, SCH), 2.80 (dd, 1H, 3J = 12.4 Hz, 2J = 4.8 Hz, SCH), 2.97 – 3.12 (m, 5H, 2 NHCH2, SCH), 4.11 (m, 1H, NHCH), 4.29 (m, 1H, NHCH), 4.70 (s, 2H, OCH2CO), 5.55 (s, 1H, C=CH), 6.06 (s, 1H, C=CH), 6.33 (s, 1H, biotin-NH), 6.39 (s, 1H, biotin-NH), 7.07 (d, 1H, 3J = 8.6 Hz, Ar-H), 7.32 (d, 1H, 3J = 8.6 Hz, Ar-H), 7.70 (br s, 1H, CONH), 8.01 (br s, 1H, CONH); 13C-NMR (DMSO-d6): δ = 12.3 (CH3), 22.9 (CH2CH3), 25.3 (CH2), 26.0 (CH2), 26.0 (CH2), 28.0 (CH2), 28.2 (CH2), 28.9 (CH2), 29.1 (CH2), 35.2 (CH2), 38.2 (CH2), 38.3 (CH2), 39.8 (SCH2), 55.4 (SCH), 59.2 (NHCH), 61.0 (NHCH), 67.9 (OCH2CO), 111.9 (Ar-CH), 121.2 (Ar-qC), 127.4 (Ar-CH), 129.3 (C=CH2), 129.9 (Ar-qC), 132.4 (Ar-qC), 149.3 (qC, C=CH2), 155.5 (Ar-qC), 162.6 (qC, NHCONH), 166.3 (qC, CONH), 171.7 (qC, CONH), 195.1 (qC, C=O); LC-MS: m/z 628.0 (100) [M+H]+, Rt = 16.3 min.
N-tert-butyl-2-(4-butyryl-2,3-dichloro-phenoxy)-acetamide (
26). Compound
26 was synthesized according to [
17] starting from 2,3-dichloro-4-butyrylphenoxyacetic acid (500 mg, 1.72 mmol),
N-hydroxysuccinimide (198 mg, 1.72 mmol), DCC (354 mg, 1.72 mmol) and
t-butylamine (251 mg, 3.43 mmol) in dichloromethane (15 mL). Reaction time: 21 d stirring at room temperature. The crude product was purified by column chromatography (SiO
2, Cy/EtOAc 1:1). Yield: 374 mg (1.08 mmol, 63 %) as white solid;
1H-NMR: δ = 0.97 (t, 3H,
3J = 7.4 Hz, CH
2C
H3), 1.41 (s, 9H, (CH
3)
3), 1.72 (sext, 2H,
3J = 7.3 Hz, C
H2CH
3), 2.88 (t, 2H,
3J = 7.2 Hz, COC
H2CH
2CH
3), 4.44 (s, 2H, OCH
2), 6.62 (br s, 1H, NH), 6.84 (d, 1H,
3J = 8.6 Hz, Ar-H), 7.38 (d, 1H,
3J = 8.6 Hz, Ar-H).
13C-NMR: δ = 13.7 (CH
2CH
3), 17.8 (
CH
2CH
3), 28.7 (C(
CH
3)
3), 44.7 (CO
CH
2), 51.5 (
C(CH
3)
3), 68.4 (OCH
2), 111.1 (Ar-CH), 123.2 (Ar-qC), 127.6 (Ar-CH), 131.4 (Ar-qC), 134.9 (Ar-qC), 155.2 (Ar-qC), 165.5 (qC, CONH), 201.8 (C=O).
N-butyl-2-(4-butyryl-2,3-dichloro-phenoxy)-acetamide (
27). Compound
27 was synthesized according to [
17] starting from 2,3-dichloro-4-butyrylphenoxyacetic acid (500 mg, 1.72 mmol),
N-hydroxy-succinimide (198 mg, 1.72 mmol), DCC (354 mg, 1.72 mmol) and
n-butylamine (251 mg, 3.43 mmol) in dichloromethane (15 mL). Reaction time: 21 d stirring at room temperature. The crude product was purified by column chromatography (SiO
2, Cy/EtOAc 1:1). Yield: 270 mg (0.880 mmol, 45 %) as a white solid;
1H-NMR: δ = 0.92 – 0.98 (m, 6H, NH(CH
2)
3C
H3, COCH
2CH
2C
H3), 1.38 (sext, 2H,
3J = 7.4 Hz, NHCH
2CH
2C
H2CH
3), 1.55 (quint, 2H,
3J = 7.3 Hz, NHCH
2C
H2CH
2CH
3), 1.72 (sextett, 2H,
3J = 7.3 Hz, COCH
2C
H2CH
3), 2.88 (t, 2H,
3J = 7.3 Hz, COC
H2CH
2CH
3), 3.37 (q, 2H,
3J = 6.7 Hz, NHC
H2), 4.55 (s, 2H, OCH
2), 6.72 (br s, 1H, NH), 6.85 (d, 1H,
3J = 8.8 Hz, Ar-H), 7.38 (d, 1H,
3J = 8.6 Hz, Ar-H);
13C-NMR: δ = 13.7 (
n-butyl-
CH
3, CH
2CH
3), 17.8 (
CH
2CH
3), 20.0 (NHCH
2CH
2CH
2CH
3), 31.5 (NHCH
2CH
2CH
2CH
3), 38.9 (NHCH
2), 44.8 (CO
CH
2CH
2CH
3), 68.2 (OCH
2), 111.0 (Ar-CH), 123.3 (Ar-qC), 127.6 (Ar-CH), 131.4 (Ar-qC), 135.0 (Ar-qC), 155.1 (Ar-qC), 166.4 (qC, CONH), 201.8 (C=O).
N-tert-butyl-2-(4-butyryl-2-fluorophenoxy)acetamide (28). Method B: Bromoacetyl bromide (2.94 g, 14.6 mmol), tert-butylamine (1.07 mg, 14.6 mmol), triethylamine (2.05 mL, 14.6 mmol); Method C: 1-(3-fluoro-4-hydroxyphenyl)butan-1-one (856 mg, 4.70 mmol), K2CO3 (974 mg, 7.05 mmol), KI (78.0 mg, 0.47 mmol), 2-bromo-N-tert-butylacetamide (see method B). Rf: 0.31 (cyclohexane/ethyl acetate: 2/1); yield 1.00 g (3.38 mmol, 72%); white solid; mp 80 °C (cyclohexane/ethyl acetate). 1H-NMR: δ 0.99 (t, 3H, 3J = 7.5 Hz, CH2CH2CH3), 1.37 (s, 9H, Cq(CH3)3), 1.75 (sext, 2H, 3J = 7.3 Hz, CH2CH2CH3), 2.88 (t, 2H, 3J = 7.2 Hz, CH2CH2CH3), 4.46 (s, 2H, OCH2C=O), 6.41 (bs, 1H, NH), 6.97 (dd, 1H, J = 8.4 Hz, CHarom.), 7.72–7.76 (m, 2H, CHarom.).
Tert-butyl-2-(4-butyryl-2-fluorophenoxy)acetate (29). Method C: 1-(3-Fluoro-4-hydroxyphenyl)butan-1-one (1.00 g, 5.49 mmol), K2CO3 (1.19 g, 8.64 mmol), KI (91.0 mg, 0.55 mmol), bromoacetic acid tert-butylester (1.50 mL, 10.2 mmol); Rf: 0.69 (cyclohexane/ethyl acetate: 1/1); yield 1.46 g (4.93 mmol, 90 %); white solid; mp 62 °C (cyclohexane/ethyl acetate); 1H-NMR: δ 0.98 (t, 3H, 3J = 7.3 Hz, CH2CH2CH3), 1.47 (s, 9H, Cq(CH3)3), 1.74 (sext, 2H, 3J = 7.3 Hz, CH2CH2CH3), 2.86 (t, 2H, 3J = 7.2 Hz, CH2CH2CH3), 4.64 (s, 2H, OCH2C=O), 6.89 (dd, 1H, J = 8.5 Hz, CHarom.), 7.68–7.72 (m, 2H, CHarom.).
N-butyl-2-(4-butyryl-2-fluorophenoxy)acetamide (30). Method B: Bromoacetyl bromide (2.08 g, 10.3 mmol), n-butylamine (753 mg, 10.3 mmol), triethylamine (1.45 mL, 10.3 mmol). Method C: 1-(3-Fluoro-4-hydroxyphenyl)butan-1-one (750 mg, 4.12 mmol), K2CO3 (853 mg, 6.17 mmol), KI (68.4 mg, 0.41 mmol), 2-bromo-N-n-butylacetamide (see method B). Rf: 0.32 (cyclohexane/ethyl acetate: 1/2); yield 1.00 g (3.39 mmol, 82 %); white solid; mp 75 °C (cyclohexane/ethyl acetate); 1H-NMR: δ 0.93 (m, 3H, NHCH2CH2CH2CH3), 0.99 (t, 3H, 3J = 7.4 Hz, CH2CH2CH3), 1.36 (sext, 2H, 3J = 7.3 Hz, NHCH2CH2CH2CH3), 1.53 (sext, 3J = 7.3 Hz, NHCH2CH2CH2CH3), 1.75 (sext, 2H, 3J = 7.3 Hz, CH2CH2CH3), 2.88 (t, 2H, 3J = 7.3 Hz, CH2CH2CH3), 3.36 (q, 2H, 3J = 6.8 Hz, NHCH2CH2CH2CH3), 4.57 (s, 2H, OCH2C=O), 6.59 (s, 1H, NH), 6.97 (dd, 1H, J = 8.3 Hz, CHarom.), 7.72–7.76 (m, 2H, CHarom.); 13C-NMR: δ 13.68 und 13.82 (CH2CH2CH3 und NHCH2CH2CH2CH3), 17.76 (CH2CH2CH3), 19.98 (NHCH2CH2CH2CH3), 31.52 (NHCH2CH2CH2CH3), 38.89 (NHCH2CH2CH2CH3), 40.24 (CH2CH2CH3), 68.15 (OCH2C=O), 114.04 (CHarom.), 116.03 (CHarom.), 125.31 (CHarom.), 131.22 (CqC=O), 149.12 (CqF or CqOCH2C=O), 153.30 (CqF or CqOCH2C=O), 166.69 (OCH2C=O), 197.84 (CqC=O).
2-(4-Butyryl-2-fluorophenoxy)-N-(1-hydroxy-2-methylpropan-2-yl)acetamide (31). Method B: Bromoacetyl bromide (0.76 mL, 8.75 mmol), 2-amino-2-methyl-1-propanol (780 mg, 8.75 mmol), triethylamine (1.23 mL, 8.75 mmol). Method C: 1-(3-Fluoro-4-hydroxyphenyl)butan-1-one (495 mg, 2.72 mmol), K2CO3 (563 mg, 4.08 mmol), KI (45.2 mg, 0.27 mmol), 2-bromo-N-(1-hydroxy-2-methylpropan-2-yl)acetamide (see method B). Rf: 0.28 (cyclohexane/ethyl acetate: 1/2); yield 455 mg (1.46 mmol, 54 %); white solid; mp 84 °C (cyclohexane/ethyl acetate); 1H-NMR: δ 0.99 (t, 3H, 3J = 7.5 Hz, CH2CH2CH3), 1.35 (s, 6H, Cq(CH3)2), 1.75 (sext, 2H, 3J = 7.4 Hz, CH2CH2CH3), 2.88 (t, 2H, 3J = 7.3 Hz, CH2CH2CH3), 3.65 (s, 2H, CqCH2OH), 4.52 (s, 2H, OCH2C=O), 6.66 (s, 1H, NH), 6.98 (dd, 1H, J = 8.1 Hz, CHarom.), 7.73–7.76 (m, 2H, CHarom.); 13C-NMR: δ 13.83 (CH2CH2CH3), 17.74 (CH2CH2CH3), 24.66 (Cq(CH3)2), 40.26 (CH2CH2CH3), 56.50 (Cq(CH3)2), 68.24 (OCH2C=O), 70.17 (CqCH2OH), 114.38 (CHarom.), 116.30 (CHarom.), 125.28 (CHarom.), 132.21 (CqC=O), 148.87 (CqF or CqOCH2C=O), 153.34 (CqF or CqOCH2C=O), 167.42 (OCH2C=O), 197.85 (CqC=O).
Methyl 2-(2-(4-butyryl-2-fluorophenoxy)acetamido)-3-methylpentanoate (
32). Method B: Bromoacetyl bromide (2.00 g, 9.92 mmol), isoleucine methylester HCl (1.80 mg, 9.92 mmol), triethylamine (2.79 mL, 19.8 mmol). Method C: 1-(3-Fluoro-4-hydroxyphenyl)butan-1-one (600 mg, 3.29 mmol), K
2CO
3 (683 mg, 4.94 mmol) KI (54.6 mg, 0.33 mmol), methyl-2-(2-bromoacetamido)-3-methyl-pentanoate (see method B)). R
f: 0.65 (cyclohexane/ethyl acetate: 1/1); yield 616 mg (1.68 mmol, 51 %); white solid; mp 74 °C (cyclohexane/ethyl acetate); [α]
= 61.1 (CHCl
3, c = 0.1);
1H-NMR: δ 0.90–0.94 (m, 6H, Ile-CH
2C
H3 and Ile-CHC
H3), 0.99 (t, 3H,
3J = 7.5 Hz, CH
2CH
2C
H3), 1.12–1.23 (m, 2H, Ile-C
H2CH
3), 1.40–1.49 (m, 1H, Ile-C
HC=O), 1.75 (sext,
3J = 7.3 Hz, CH
2C
H2CH
3), 1.92–1.99 (m, 1H, Ile-C
HCH
3), 2.88 (t, 2H,
3J = 7.3 Hz, C
H2CH
2CH
3), 3.74 (s, 3H, OC
H3), 4.62 (s, 2H, OC
H2C=O), 6.99 (dd, 1H,
3J = 8.5 Hz, C
Harom.), 7.08 (d, 1H,
J = 8.5 Hz, N
H), 7.72–7.77 (m, 2H, C
Harom.).