A Chiral Probe for the Asynchronous Transition State of Diels-Alder Reactions with Acetylenedicarboxylate

摘要

Diels-Alder reactions took place with modest diastereoselectivity between dimethylcyclohexadiene derivative 3a and di-(-)-menthyl acetylenedicarboxylate, whereas the dimethylcyclohexadiene 2 showed no selectivity whatsoever. These results can be rationalized in terms of a complete lack of any endo-exo preference for the carboxylate groups and a more synchronous addition with 3a than with 2.