NaOH-Promoted Thiolysis of Oxiranes Using 2-[Bis(alkylthio)methylene]-3-oxo-N-o-tolylbutanamides as Odorless Thiol Equivalents

Abstract

A convenient and efficient protocol for the thiolysis of oxiranes using 2-[bis(alkylthio)methylene]-3-oxo-N-o-tolylbutan­amides as thiol equivalents has been developed. Promoted by sodium hydroxide (NaOH) in ethanol at room temperature, the cleavage commences and the generated thiolate anions undergo nucleophilic addition in situ. β-Hydroxy sulfides were obtained in high yields along with good β-regioselectivity, and trans β-hydroxy sulfides were also isolated. The thiolysis of one α,β-epoxyketone product with the thiol equivalents was accomplished to afford the corresponding α-carbonyl sulfides in excellent yields. In all the cases, 3-oxo-N-o-tolylbutanamide, the precursor of the thiol equivalents, could be recovered in the novel thiolysis process as a byproduct in good yield.

α-carbonyl sulfides - epoxides - β-hydroxy sulfides - α-oxo ketene-S,S-acetals - thiolysis

References and Notes

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Thiolysis of 2 with 1 (4a as Example); Typical Procedure: To a 25 mL flask containing NaOH (1.0 mmol) in EtOH (5 mL) were added 1a (1.0 mmol) and 2a (2.0 mmol) under stirring. The mixture was stirred at r.t. for about 50 min, after which time the reaction was complete as indicated by TLC. The resulting mixture was neutralized with aq HCl (0.1 N, 10 mL), and extracted with Et₂O (3 × 15 mL). The combined organic extracts were washed with H₂O (3 × 15 mL), dried over MgSO₄, filtered and concentrated in vacuo. Separation was carried out by silica gel chromatography using PE-Et₂O (10:1) as eluent to afford product 4a in 90% yield. Selected Data for Compounds 4-6: Compounds 4a, 4d, 4i and 5d are known, and were identified by ¹H NMR, IR spectroscopy and elemental analyses, the data for these compounds are in good agreement with those in literature (refs. 6e-g).
1-(Butylthio)propan-2-ol (4b): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 0.83-0.86 (m, 3 H), 1.17-1.20 (m, 3 H), 1.31-1.37 (m, 2 H), 1.48-1.51 (m, 2 H), 2.36-2.42 (m, 1 H), 2.45-2.49 (m, 2 H), 2.61-2.65 (m, 1 H), 2.91 (br, 1 H), 3.77 (br, 1 H). ¹³C NMR (125 MHz, CDCl₃): δ = 13.5, 21.8 (2 × C), 31.7, 31.8, 41.5, 65.3. IR (KBr, neat): 3340, 2925, 1734, 1539, 1459, 1284 cm^-1. Anal. Calcd for C₇H₁₆OS: C, 56.71; H, 10.88. Found: C, 56.82; H, 10.96.
1-(Ethylthio)propan-2-ol (4c): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 0.80-0.86 (m, 3 H), 1.25-1.28 (m, 3 H), 2.41-2.46 (m, 1 H), 2.54-2.58 (m, 2 H), 2.63 (br, 1 H), 2.73-2.76 (m, 1 H), 3.83-3.85 (m, 1 H). ¹³C NMR (125 MHz, CDCl₃): δ = 15.8, 21.7, 31.6, 41.2, 65.4. IR (KBr, neat): 2955, 2869, 1458, 1247, 1200 cm^-1. Anal. Calcd for C₅H₁₂OS: C, 49.96; H, 10.06. Found: C, 49.81; H, 10.14.
2-(Butylthio)-1-phenylethanol (4e): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 0.91-0.94 (m, 3 H), 1.38-1.45 (m, 2 H), 1.56-1.62 (m, 2 H), 2.53-2.56 (m, 2 H), 2.70-2.74 (m, 1 H), 2.91-2.94 (m, 1 H), 3.10 (br, 1 H), 4.72-4.74 (m, 1 H), 7.28-7.31 (m, 1 H), 7.31-7.39 (m, 4 H). ¹³C NMR (125 MHz, CDCl₃): δ = 13.9, 22.2, 31.9, 32.0, 42.3, 71.8, 126.1 (2 × C), 128.1, 128.8 (2 × C), 142.8. IR (KBr, neat): 3426, 3029, 2926, 1740, 1456, 1274 cm^-1. Anal. Calcd for C₁₂H₁₈OS: C, 68.52; H, 8.63. Found: C, 68.64; H, 8.72.
2-(Butylthio)-2-phenylethanol (5e): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 0.84-0.87 (m, 3 H), 1.31-1.39 (m, 2 H), 1.48-1.54 (m, 2 H), 2.09 (br, 1 H), 2.42-2.45 (m, 2 H), 3.83-3.87 (m, 2 H), 3.94-3.97 (m, 1 H), 7.26-7.28 (m, 1 H), 7.29-7.38 (m, 4 H). ¹³C NMR (125 MHz, CDCl₃): δ = 13.9, 22.2, 31.1, 31.8, 53.2, 65.8, 127.9, 128.2 (2 × C), 129.0 (2 × C), 139.1. IR (KBr, neat): 3386, 3028, 2927, 1713, 1538, 1456, 1276 cm^-1. Anal. Calcd for C₁₂H₁₈OS: C, 68.52; H, 8.63. Found: C, 68.67; H, 8.58.
2-(Ethylthio)-1-phenylethanol (4f): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 1.25-1.30 (m, 3 H), 2.53-2.58 (m, 2 H), 2.70-2.75 (m, 1 H), 2.90-2.94 (m, 1 H), 4.71-4.73 (m, 1 H), 7.26-7.30 (m, 1 H), 7.31-7.38 (m, 4 H). ¹³C NMR (125 MHz, CDCl₃): δ = 15.1, 26.3, 41.8, 71.9, 126.1 (2 × C), 128.1, 128.8 (2 × C), 142.7. IR (KBr, neat): 3424, 3029, 2921, 1720, 1540, 1451, 1265 cm^-1. Anal. Calcd for C₁₀H₁₄OS: C, 65.89; H, 7.74. Found: C, 65.73; H, 7.62.
2-(Ethylthio)-2-phenylethanol (5f ): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 1.19-1.22 (m, 3 H), 2.04-2.07 (m, 1 H), 2.42-2.49 (m, 2 H), 3.84-3.89 (m, 2 H), 3.97-4.00 (m, 1 H), 7.26-7.28 (m, 1 H), 7.28-7.35 (m, 4 H). ¹³C NMR (125 MHz, CDCl₃): δ = 15.0, 25.4, 52.8, 65.8, 127.9, 128.3 (2 × C), 129.0 (2 × C), 140.0. IR (KBr, neat): 3334, 3028, 2924, 1712, 1540, 1453, 1265 cm^-1. Anal. Calcd for C₁₀H₁₄OS: C, 65.89; H, 7.74. Found: C, 65.77; H, 7.81.
2-(Methylthio)-1-phenylethanol (4g): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 2.13 (s, 3 H), 2.71-2.76 (m, 1 H), 2.86-2.89 (m, 1 H), 3.02 (br, 1 H), 4.76-4.78 (m, 1 H), 7.29-7.31 (m, 1 H), 7.32-7.38 (m, 4 H). ¹³C NMR (125 MHz, CDCl₃): δ = 15.4, 44.0, 71.1, 125.7 (2 × C), 127.8, 128.4 (2 × C), 142.4. IR (KBr, neat): 3421, 3029, 2915, 1721, 1540, 1449, 1235 cm^-1. Anal. Calcd for C₉H₁₂OS: C, 64.25; H, 7.19. Found: C, 64.13; H, 7.24.
2-(Methylthio)-2-phenylethanol (5g): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 1.99 (s, 3 H), 2.06 (br, 1 H), 3.87-3.90 (m, 3 H), 7.26-7.29 (m, 1 H), 7.30-7.37 (m, 4 H). ¹³C NMR (125 MHz, CDCl₃): δ = 13.7, 54.0, 64.8, 127.6, 127.9 (2 × C), 128.6 (2 × C), 139.0. IR (KBr, neat): 3358, 3027, 2923, 1722, 1597, 1458, 1269 cm^-1. Anal. Calcd for C₉H₁₂OS: C, 64.25; H, 7.19. Found: C, 64.36; H, 7.15.
2-(Allylthio)-1-phenylethanol (4h): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 2.66-2.71 (m, 1 H), 2.86-2.90 (m, 1 H), 2.94 (br, 1 H), 3.10-3.19 (m, 2 H), 4.72-4.74 (m, 1 H), 5.10-5.15 (m, 2 H), 5.75-5.83 (m, 1 H), 7.28-7.31 (m, 1 H), 7.32-7.37 (m, 4 H). ¹³C NMR (125 MHz, CDCl₃): δ = 34.9, 40.2, 72.0, 118.0, 126.1 (2 × C), 128.1, 128.8 (2 × C), 134.3, 142.9. IR (KBr, neat): 3425, 3030, 2914, 1715, 1540, 1452, 1228 cm^-1. Anal. Calcd for C₁₁H₁₄OS: C, 68.00; H, 7.26. Found: C, 68.21; H, 7.21.
2-(Allylthio)-2-phenylethanol (5h): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 1.94-1.96 (m, 1 H), 2.98-3.02 (m, 1 H), 3.11-3.15 (m, 1 H), 3.85-3.88 (m, 2 H), 3.94-3.97 (m, 1 H), 5.05-5.12 (m, 2 H), 5.75-5.81 (m, 1 H), 7.27-7.29 (m, 1 H), 7.30-7.37 (m, 4 H). ¹³C NMR (125 MHz, CDCl₃): δ = 34.3, 51.6, 65.9, 117.8, 127.9, 128.5 (2 × C), 129.0 (2 × C), 134.4, 139.7. IR (KBr, neat): 3388, 3028, 2919, 1711, 1538, 1454, 1230 cm^-1. Anal. Calcd for C₁₁H₁₄OS: C, 68.00; H, 7.26. Found: C, 68.12; H, 7.19. 2-(Butylthio)cyclohexanol (4j): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 0.89 (t, J = 7.5 Hz, 3 H), 1.22-1.29 (m, 3 H), 1.36-1.44 (m, 3 H), 1.51-1.57 (m, 2 H), 1.68-1.73 (m, 2 H), 2.04-2.10 (m, 2 H), 2.31-2.37 (ddd, J = 4.0, 9.5, 12.5 Hz, 1 H), 2.53 (m, 2 H), 3.03 (br, 1 H), 3.25-3.27 (m, 1 H). ¹³C NMR (125 MHz, CDCl₃): δ = 13.6, 22.0, 24.4, 26.2, 29.4, 32.3, 32.9, 33.7, 53.4, 72.0. IR (KBr, neat): 3450, 2930, 1449, 1227 cm^-1. Anal. Calcd for C₁₀H₂₀OS: C, 63.77; H, 10.70. Found: C, 63.89; H, 10.62.
2-(Benzylthio)-1-phenylethanone (6a): colorless crystal; mp 68-70 °C. ¹H NMR (500 MHz, CDCl₃): δ = 3.68 (s, 2 H), 3.76 (s, 2 H), 7.25-7.27 (m, 2 H), 7.32-7.48 (m, 3 H), 7.47-7.49 (m, 2 H), 7.51-7.53 (m, 1 H), 7.93-7.95 (m, 2 H). ¹³C NMR (125 MHz, CDCl₃): δ = 35.6, 35.8, 127.0, 128.3 (2 × C), 128.4 (2 × C), 128.5 (2 × C), 129.0 (2 × C), 133.0, 135.1, 137.0, 194.2. IR (KBr, neat): 3058, 2923, 1672, 1545, 1450, 1200 cm^-1. Anal. Calcd for C₁₅H₁₄OS: C, 74.34; H, 5.82. Found: C, 74.48; H, 5.77.
2-(Butylthio)-1-phenylethanone (6b): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 0.82-0.92 (m, 3 H), 1.34-1.42 (m, 2 H), 1.54-1.60 (m, 2 H), 2.54-2.57 (m, 2 H), 3.78 (s, 2 H), 7.45-7.48 (m, 2 H), 7.55-7.58 (m, 1 H), 7.95-7.98 (m, 2 H). ¹³C NMR (125 MHz, CDCl₃): δ = 12.7, 20.9, 30.0, 31.0, 36.1, 127.6 (2 × C), 127.8 (2 × C), 132.3, 134.2, 193.5. IR (KBr, neat): 3021, 2950, 1739, 1687, 1511, 1461, 1274 cm^-1. Anal. Calcd for C₁₂H₁₆OS: C, 69.19; H, 7.74. Found: C, 69.38; H, 7.67.
2-(Ethylthio)-1-phenylethanone (6c): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 1.27 (t, J = 7.5 Hz, 3 H), 2.59 (q, J = 7.5 Hz, 2 H), 3.80 (s, 2 H), 7.46-7.49 (m, 2 H), 7.56-7.59 (m, 1 H), 7.98 (d, 2 H). ¹³C NMR (125 MHz, CDCl₃): δ = 13.1, 25.3, 35.7, 127.3, 127.7 (2 × C), 127.8 (2 × C), 132.3, 193.5. IR (KBr, neat): 3061, 2967, 1675, 1450, 1276 cm^-1. Anal. Calcd for C₁₀H₁₂OS: C, 66.63; H, 6.71. Found: C, 66.51; H, 6.65.
2-(Methylthio)-1-phenylethanone (6d): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 2.13 (s, 3 H), 3.76 (s, 2 H), 7.45-7.48 (m, 2 H), 7.56-7.59 (m, 1 H), 7.95-7.98 (m, 2 H). ¹³C NMR (125 MHz, CDCl₃): δ = 14.9, 38.0, 127.7, 127.8, 127.9 (2 × C), 132.4, 134.1, 193.0. IR (KBr, neat): 3060, 2918, 1672, 1579, 1447, 1278 cm^-1. Anal. Calcd for C₉H₁₀OS: C, 65.02; H, 6.06. Found: C, 65.20; H, 6.12.
2-(Allylthio)-1-phenylethanone (6e): colorless liquid. ¹H NMR (500 MHz, CDCl₃): δ = 3.18 (d, J = 7.5 Hz, 2 H), 3.76 (s, 2 H), 5.15-5.21 (m, 2 H), 5.74-5.80 (m, 1 H), 7.45-7.48 (m, 2 H), 7.55-7.58 (m, 1 H), 7.96 (d, J = 7.5 Hz, 2 H). ¹³C NMR (125 MHz, CDCl₃): δ = 34.9, 35.7, 118.8, 128.9, 129.0, 129.1, 129.2, 133.2, 133.6, 134.2, 194.7. IR (KBr, neat): 3061, 2917, 1676, 1540, 1449, 1275 cm^-1. Anal. Calcd for C₁₁H₁₂OS: C, 68.71; H, 6.29. Found: C, 68.58; H, 6.37.

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