Model studies on the synthesis of medium-sized and large carbocycles using the Ireland enolate Claisen rearrangement

Abstract

Model studies have shown that the enolate Claisen rearrangement, a modification (developed by R. E. Ireland et al.) of the original Claisen rearrangement, can successfully be applied to the elaboration of medium-sized and large carbocycles from O-silyl enolates of suitable unsaturated macrolides (Scheme). The rearrangements are largely non-stereoselective, a fact which can be rationalised in terms of the intermediacy of both chair- and boat-like transition states and possibly because, in some cases, both the (E)- and (Z)-enolate of the macrolides are involved.