A Simple Synthesis of Annulated Bicyclo (2.2.2)-Octenones

Abstract

Bicyclo (2.2.2) octanes disposed with β,γ-unsaturated carbonyl chromophore are versatile intermediates for the synthesis of many carbocyclic structures of current interest¹. Recently they have also been shown to have great potential towards synthesis of a variety of natural products². We became interested in acquisition of functionalized annulated bicyclo (2.2.2) octenones of type 1 (Scheme-1) in connection with an exploratory project on the synthesis of polycyclopentanoids. In this context we recently reported that a trapping of a 2, 4-cyclohexadienone with cyclic dienes provides a facile entry into such ring systems³. We now further report an expeditious one step synthesis of annulated bicyclo (2.2.2) octenones 10–15 (Scheme-1) by trapping the 2, 4-cyclohexadienone 3 with various dienophiles 4–9(Scheme-1).