Facial Selectivity of the Ireland—Claisen Rearrangement of Allylic Esters of 2‐Methyl and 2‐Methoxycyclopentanecarboxylic Acids.

Abstract

Facial Selectivity of the Ireland-Claisen Rearrangement of Allylic Esters of 2-Methyl and 2-Methoxycyclopentanecarboxylic Acids. -The stereoselectivity of the Ireland-Claisen rearrangement of 2-methyl and 2-methoxy substituted cyclopentane-carboxylate systems is investigated. The studies reveal that the 2-methyl-substituted systems rearrange with complete facial selectivity at the ring position, but the (Z)-or (E)-crotyl systems give a mixture of diastereomers. In contrast, a 2-methoxy group in the five-membered ring system (VI) does not control the diastereoselectivity. -(GILBERT*, J. C.; YIN, J.; FAKHREDDINE, F. H.; KARPINSKI, M. L.; Tetrahedron 60 (2004) 1, 51-60; Dep. Chem. Biochem., Univ. Tex., Austin, TX 78712, USA; Eng.) -Bartels 20-061