(1.56Н, d, J = 6.7, СН(СН3)2); 1.87-2.04 (0.52Н, m, СНМе2); 2.70 (0.52H, dd, JАВ = 10.0, JАХ = 9.1) and 3.03
(0.52H, dd, JАВ = 10.0, JВХ = 7.0, 5-СН2); 3.70 (0.52Н, dd, JАХ = 9.1, JВХ = 7.0, 4-СН); 4.22 (0.52Н, d, J = 7.7,
2-СН); (2S,4R) isomer (48%): 0.96 (1.44Н, d, J = 6.7) and 1.01 (1.44Н, d, J = 6.7, СН(СН3)2); 1.70-1.81
(0.48Н, m, СНМе2); 2.90 (0.48H, dd, JАВ = 10.0, JАХ = 5.4) and 3.17 (0.48H, dd, JАВ = 10.0, JВХ = 6.7, 5-СН2);
4.03 (0.48Н, dd, JАХ = 5.4, JВХ = 6.7, 4-СН); 4.34 (0.48Н, d, J = 8.0, 2-СН). 13C NMR spectrum, δ, ppm:
(2R,4R)-isomer: 20.6 (CH3); 20.9 (CH3); 33.1 (CH); 36.8 (C-5); 65.4 (C-4); 78.1 (C-2); 172.5 (COOH);
(2S,4R)-isomer: 20.1 (CH3); 20.8 (CH3); 34.2 (CH); 36.7 (C-5); 64.5 (C-4); 77.2 (C-2); 173.0 (COOH). Found,
%: C 48.06; H 7.40; N 8.07. C7H13NO2S. Calculated, %: C 47.98; H 7.48; N 7.99.
(2RS,4R)-2-Isobutylthiazolidine-4-carboxylic Acid (2b). Yield 1.32 g (70%). Colorless crystals.
Mp 165-167°С (mp 163-165°С [21]). 1H NMR spectrum, δ, ppm (J, Hz): (2R,4R) isomer (60%): 0.89 (3.6H, d,
J = 6.4, СН(CH3)2); 1.63-1.67 (1.2H, m, СН2СНМе2); 1.77-1.82 (0.6H, m, СНМе2); 2.75 (0.6H, dd, JАВ = 10.0,
JАХ = 9.0) and 3.19 (0.6H, dd, JАВ = 10.0, JВХ = 7.0, 5-СН2); 3.70 (0.6Н, dd, JАХ = 9.0, JВХ = 7.0, 4-СН); 4.46
(0.6Н, t, J = 7.0, 2-СН); (2S,4R) isomer (40%): 0.90 (2.4H, d, J = 6.4, СН(CH3)2); 1.63-1.67 (0.8H, m,
СН2СНМе2); 1.74-1.78 (0.4H, m, СНМе2); 2.94 (0.4H, dd, JАВ = 10.3, JАХ = 5.0) and 3.08 (0.4H, dd,
J
АВ = 10.3, JВХ = 7.0, 5-СН2); 4.08 (0.4Н, dd, JАХ = 5.0, JВХ = 7.0, 4-СН); 4.61 (0.4Н, t, J = 7.2, 2-СН).
13C NMR spectrum, δ, ppm: (2R,4R) isomer: 22.3 (2CH3); 27.1 (CH); 37.2 (C-5); 44.0 (CH2); 65.3 (C-4); 69.6
(C-2); 172.0 (COOH); (2S,4R)-isomer: 22.3 (2CH3); 26.8 (CH); 36.8 (C-5); 45.6 (CH2); 64.2 (C-4); 68.8 (C-2);
173.5 (COOH). Found, %: C 50.81; H 8.06; N 7.39. C8H15NO2S. Calculated, %: C 50.77; H 7.99; N 7.40.
(2RS,4R)-2-(2-Phenylethyl)thiazolidine-4-carboxylic Acid (2c). Yield 2.02 g (85%). Colorless
1
crystals. Mp 173-175°С. H NMR spectrum, δ, ppm (J, Hz): (2R,4R) isomer (50%): 2.18-2.23 (1.0H, m,
CH2CH2Ph); 2.65-2.69 (1.0H, m, CH2CH2Ph); 2.79 (0.5H, dd, JАВ = 10.0, JАХ = 9.1) and 3.19 (0.5H, dd,
JАВ = 10.0, JВХ = 7.0, 5-СН2); 3.71 (0.5Н, dd, JАХ = 9.1, JВХ = 7.0, 4-СН); 4.37 (0.5Н, t, J = 6.7, 2-СН);
7.27-7.38 (2.5H, m, H Ph); (2S,4R) isomer (5%): 2.17-2.21 (1.0H, m, CH2CH2Ph); 2.65-2.69 (1.0H, m,
CH2CH2Ph); 2.93 (0.5H, dd, JАВ = 10.1, JАХ = 5.4) and 3.19 (0.5H, dd, JАВ = 10.1, JВХ = 7.0, 5-СН2); 4.09
(0.5Н, dd, JАХ = 5.4, JВХ = 7.0, 4-СН); 4.54 (0.5Н, t, J = 6.7, 2-СН); 7.27-7.38 (2.5H, m, H Ph). 13C NMR
spectrum, δ, ppm: (2R,4R) isomer: 33.5 (CH2); 37.1 (C-5); 38.8 (CH2); 65.4 (C-4); 70.5 (C-2); 125.9, 128.4,
128.6, 141.4 (C Ph); 172.4 (COOH); (2S,4R) isomer: 33.7 (CH2); 36.9 (C-5); 38.7 (CH2); 64.2 (C-4); 69.7
(C-2); 126.0, 128.3, 128.5, 141.3 (C Ph); 172.9 (COOH). Found, %: C 60.67; H 6.44; N 5.83. C12H15NO2S.
Calculated, %: C 60.73; H 6.37; N 5.90.
(2RS,4R)-2-(2-Hydroxyphenyl)thiazolidine-4-carboxylic Acid (2d). Yield 1.91 g (85%). Colorless
1
crystals. Mp 172-174°С (mp 173-175°С [22]). H NMR spectrum, δ, ppm (J, Hz): (2R,4R) isomer (45%): 2.97
(0.45H, dd, JАВ = 10.0, JАХ = 9.0) and 3.34 (0.45H, dd, JАВ = 10.0, JВХ = 7.0, 5-СН2); 3.83 (0.45Н, dd,
J
АХ = 9.0, JВХ = 7.0, 4-СН); 5.65 (0.45Н, s, 2-СН); 6.75-7.36 (1.80H, m, H Ar); (2S,4R) isomer (55%): 3.02
(0.55H, dd, JАВ = 10.0, JАХ = 5.5) and 3.21 (0.55H, dd, JАВ = 10.0, JВХ = 6.5, 5-СН2); 4.21 (0.55Н, dd,
J
АХ = 5.5, JВХ = 6.5, 4-СН); 5.85 (0.55Н, s, 2-СН); 6.75-7.36 (2.20H, m, H Ar). 13С NMR spectrum, δ, ppm:
(2R,4R) isomer: 38.3 (C-5); 65.4 (C-4); 67.8 (C-2); 115.8, 119.1, 124.3, 127.7, 128.0, 155.3 (C Ar); 172.6
(COOH); (2S,4R) isomer: 37.2 (C-5); 64.9 (C-4); 65.7 (C-2); 115.2, 118.9, 126.2, 128.2, 129.1, 154.7 (C Ar);
173.1 (COOH). Found, %: C 53.26; H 5.01; N 6.15. C10H11NO3S. Calculated, %: C 53.32; H 4.92; N 6.22.
Preparation of 2-Substituted (2R,4R)-3-(3-acetylsulfanyl)propionylthiazolidine-4-carboxylic Acids
3а-d (General Method). A solution of compound 2а-d (10 mol) in a mixture of acetone (30 ml) and pyridine
(1 ml) was treated at 0-5°С with 3-(acetylsulfanyl)propionyl chloride (1.82 g, 11 mmol) and maintained for
5-10 h. Water (30 ml) was added after the removal of solvent at reduced pressure, and the mixture was neutralized
with 0.1 М HCl solution. The mixture was extracted with EtOAc, dried over Na2SO4, the solvent was removed at
reduced pressure, the residue was reprecipitated or crystallized by the addition of 4:1 Et2O–hexane mixture.
(2R,4R)-3-(3-Acetylsulfanyl)propionyl-2-isopropylthiazolidine-4-carboxylic Acid (3a). Yield 1.83 g
1
(60%). Colorless crystals. Mp 67-70°С. [α]D25 -101.1 (c 1.25, MeOH). H NMR spectrum, δ, ppm: cis isomer
(34%): 0.85 (1.02Н, d, J = 6.5) and 0.89 (1.02Н, d, J = 6.5, СН(CH3)2); 1.90-1.95 (0.34Н, m, CHМе2); 2.30
(1.02Н, s, СОCH3); 2.60-2.77 (0.68Н, m, 5-СН2); 2.97-3.02 (0.68Н, m, NСОСН2); 3.23-3.27 (0.68Н, m,
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