Johnson Orthoester Claisen Rearrangement

Abstract

The stereoselective synthesis of γ,δ‐unsaturated esters from the reaction between allylic alcohols and an orthoester in the presence of a trace amount of weak acid, such as propionic acid is referred to as the Johnson orthoester Claisen rearrangement. This reaction involves the formation of mixed orthoester from allyl alcohol and the added orthoester. This reaction has been explored to start with sulfonyl orthoesters. The importance of this reaction has been evidenced in the preparation of a variety of natural products, such as squalenes.