Maleic anhydrides in synthesis. Preparation of furan-2(5H)-one phosphonate derivatives and a new synthesis of pulvinic acids and pulvinone analogues

Abstract

Reactions between substituted maleic anhydrides, viz. 1, and sodium dimethyl phosphite in refluxing benzene are shown to lead to the corresponding furan-2(5H)-one phosphonates 2 and 8. Wadsworth–Emmons olefination reactions involving 2 and heteroarylaldehydes and arylbenzoyl formates 14 then provides a new synthesis of heterocyclic analogues of pulvinones, i.e.10–13, and of permethylated pulvinic acids, e.g.16–17 which are found in higher fungi.