A Mild and Convenient Procedure for Desulfinylation of p-Toluenesulfinyl Amines

Abstract

Reaction of p-toluenesulfinyl amines with thiophenol in the presence of catalytic amount of ZnCl₂ provides the corresponding desulfinylated amines in high yield.

Key word

desulfinylation - Lewis acid catalyst - amine - sulfinamide

References

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9

General Procedure for Desulfinylation. Under argon atmosphere, p-toluenesulfinyl amine (1 mmol) was dissolved in CH₂Cl₂ (4 mL). Anhyd ZnCl₂ (0.1 mmol) and PhSH (3 mmol) were added, the reaction mixture was stirred at r.t. and monitored by TLC. After completion, the reaction mixture was quenched by addition of sat. NH₄Cl solution (10 mL). The aqueous phase was extracted with CH₂Cl₂ (3 × 10 mL), and the combined organic layers were dried over Na₂SO₄, concentrated, and purified by column chromatography over silica gel to give the product.
1-(4-Chlorophenyl)but-3-en-1-amine ( 2f): ¹H NMR (CDCl₃/TMS, 300 MHz): δ (ppm): 2.32-2.43 (m, 2 H), 3.99 (dd, J = 7.9, 5.5 Hz, 1 H), 5.07-5.14 (m, 2 H), 5.71-5.73 (m, 1 H), 7.18-7.39 (m, 4 H).
(2 R ,3 S )-2-Amino-3-(benzylamino)-4-[(4-chloro-phenyl)thio]butanenitrile ( 2g): ¹H NMR (400 MHz, CDCl₃-D₂O): δ = 2.93-2.98 (m, 1 H), 3.03 (dd, J ₁ = 13.6 Hz, J ₂ = 6.0 Hz, 1 H), 2.97-3.02 (m, 1 H), 3.18 (dd, J ₁ = 13.6 Hz, J ₂ = 6.7 Hz, 1 H), 3.85, 3.89 (AB, J = 13.4 Hz, 2 H), 3.93 (d, J = 3.8 Hz, 1 H), 7.20-7.33 (m, 9 H). [α]_D ²⁰ +39.2 (c 1.12, CHCl₃). IR (neat): 3385, 3324, 2231 cm^-1. MS (EI): m/z (%) = 32 (16) [M + 1], 276 (60), 91 (100). Anal. Calcd for C₁₇H₁₈ClN₃S: C, 61.53; H, 5.47; N, 12.66. Found: C, 61.27; H, 5.68; N, 12.51.

10

The ee value of product 2d determined by HPLC was the same as that of α-methylbenzylamine used as starting material to prepare p-toluenesulfinyl amine (1d).