Synthesis of highly substituted cyclohexenes via mixed Lewis acid-catalyzed Diels-Alder reactions of highly substituted dienes and dienophiles

摘要

A high-yielding method is described for the rapid synthesis of very hindered cyclohexenes by the Diels-Alder reaction of hindered silyloxy dienes and dienophiles using the mixed Lewis acid catalyst system (AlBr3/AlMe3). Thus, reaction of the hindered diene 4 with various substituted enones gave good yields of the expected cycloadducts even though both partners are quite sterically hindered.