CONVERSION OF ALLYLIC CARBAMATES INTO OLEFINS WITH LITHIUM DIMETHYLCUPRATE - NEW FORMAL SN2' REACTION

Coupling of LiCuMe2 with acetates of cyclic allylic alcohols was shown by Goering1 to proceed with anti attack and com-petitive α/γ substitution at the allylic system. An allylic cyclopentenyl lactone2 and cyclohexenyl mesitoates,3 where α/γ substitution appears to be controlled by steric factors, werefound to react accordingly. Previous work on noncyclic allylicesters4 showed that α/γ attack is little affected by the natureof the leaving group and primarily controlled by the degree ofsubstitution of the two ends of the allylic system.5 We report that coupling of cis-and trans-l-deuterio-5-phenyl-2-cyclo-hexenylcarbamates la and 2a (R = CONHPh) with LiCuMe2 gives the syn SN2ʹ products, 3a and 4a, respectively. Exclusivesyn γ attack on the allylic system has been thus achieved.© 1979, American Chemical Society. All rights reserved.