Cyclisation of arylpropiolyl chloro-oxalyl anhydrides: the chemistry of aryl(chloro)methylenetetrahydrofuran-2,4,5-triones and the X-ray crystal structure of a 3,4-methylenedioxybenzylidene representative

Abstract

3,4-Methylenedioxyphenylpropiolic acid and oxalyl chloride form a mixed anhydride which cyclises to give a red, water-sensitive aryl(chloro)methylenetetrahydrofuran-2,4,5-trione : its mixed Z,E-geometry has been investigated by single crystal X-ray methods. Arylpropiolic acids with substituents providing sufficient electron release undergo the cyclisation, but in other cases arylnaphthalenedicarboxylic anhydrides and arylpropiolyl chlorides are formed. The mechanism of the cyclisation is considered, and some reactions of the trione are described.