pi-Facial Selecivity in Diels-Alder Reactions of cross-conjugated ketones bearing an oxa-Spiro-ring with sterically undemanding dienes

摘要

The Diels-Alder reactions of cross-conjugated ketones bearing an oxa-spiro-ring with some simple sterically undemanding dienes (cyclopentadiene, 2,3-cyclohexadiene, 2,3-dimethyl-1,3-butadiene) afforded the adduct with high pi-facial selectivity under mild conditions. The pi-facial selectivity can be explained in terms of Cieplak model.