NEW STEREOSELECTIVE SYNTHESIS OF TRANS-2,5-DISUBSTITUTED PYRROLIDINES BY CYCLIZATION OF AMINYL RADICALS GENERATED FROM 2-SUBSTITUTED AND/OR 5-SUBSTITUTED N-CHLORO-N-ALKYLALK-4-ENYLAMINES WITH BU(3)SNH-AZOISOBUTYRONITRILE

trans-N-Alkyl-2- and/or 5-substituted pyrrolidines are stereoselectively formed in up to 63% yields by N-chlorination of 2- and/or 5-substituted N-methylpent-4-enylamine with N-chloro-succinimide, followed by heating a solution of the resulting N-chloro-unsaturated amines in benzene with Bu(3)SnH-azoisobutyronitrile under reflux; a pathway involving stereoselective cyclization of neutral aminyl radicals is proposed.