REARRANGEMENTS AND CYCLIZATIONS IN VINYL RADICALS - UNUSUAL EXAMPLE OF 1,4-RADICAL TRANSLOCATION

Vinyl radical 5 undergoes 5-exo cyclization onto the CC double bond in competition with the 5-exo cyclization onto the aryl ring. In additio n, radical 5 exhibits an unusual 1,4-radical translocation/beta-fragme ntation process. In contrast, radical 4 exclusively undergoes 5-exo cy clization onto the benzene ring. This latter reaction leads to spiro r adical intermediates which can either give the 1,4-aryl migration prod ucts or can be trapped by 2-cyano-iso-propyl radicals. Copyright (C) 1 996 Published by Elsevier Science Ltd