Stereoselective Synthesis of (S)‐3,4‐Methylenedioxyamphetamines from (R)‐Cyanohydrins

Abstract

AbstractA stereoselective synthesis of (S)‐3,4‐methylenedioxyamphetamines (S)‐7, which are highly interesting as psychoactive compounds, is described. Starting from readily available (R)‐cyanohydrins (R)‐2 the 2‐amino‐1‐aryl alcohols (1R,2S)‐4 were obtained with high diastereoselectivity by addition of Grignard reagents to the O‐protected cyanohydrins (R)‐3, transimination of the addition products A with primary amines, and hydrogenation of the imino intermediates B with NaBH4. For the hydrogenation of the benzylic hydroxyl group in the 1,2‐amino alcohols (1R,2S)‐4 a new, very efficient method was developed. The optically pure amphetamines (S)‐7 were obtained under very mild conditions by catalytic hydrogenation of the oxazolidinones (4S,5R)‐6, which were readily available by phosgenation of the amino alcohols (1R,2S)‐4.