Facile Synthesis of Sulfonyl Amidines and β-Amino Sulfonyl Enamines under Transition-Metal-Free Conditions

Abstract

Treatment of enamine and azide resulted in the formation of either sulfonyl amidine or β-amino sulfonyl enamine derivative in moderate to good yields. The reaction could proceed under catalyst-free conditions.

Key words

enamine - azide - amidine - catalyst-free

References and Notes

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10

Typical Procedure for the Preparation of 4-Methyl- N -[morpholino(phenyl)methylene]benzenesulfonamide (3): To a stirred solution of 4-(1-phenylvinyl)morpholine (0.1 mmol) and CH₂Cl₂ (0.1 mL), p-toluenesulfonyl azide (0.15 mmol) was added successively. The mixture was kept at r.t. under air and stirred for 20 min. The mixture was then extracted with EtOAc, dried over MgSO₄ and filtered. The filtrate was removed under reduced pressure to get the crude product, which was further purified by silica gel chroma-tography (PE-EtOAc, 1:1) to give the product 3 as a white solid. ^¹H NMR (400 MHz, CDCl₃): δ = 2.36 (s, 3 H), 3.11-3.13 (m, 2 H), 3.53-3.56 (m, 2 H), 3.76-3.78 (m, 2 H), 3.92-3.95 (m, 2 H), 7.12-7.16 (m, 4 H), 7.34-7.45 (m, 3 H), 7.49-7.51 (m, 2 H). ^¹³C NMR (100 MHz, CDCl₃): δ = 21.4, 45.0, 48.2, 66.3, 66.7, 126.5, 127.3, 128.4, 128.8, 130.0, 131.3, 140.6, 141.7, 165.8.