Nucleophilic alkenes. IV. Addition of 1,1-dialkoxyethenes to 1,4-benzoquinones. The 1 : 1-process

Abstract

Reaction of 1,4-benzoquinones with 1,1-dialkoxyethenes in dimethyl sulfoxide gave high yields of 1,4-naphthoquinones by 1 : 2-addition. Hexahydro- and dihydro-naphthoquinone intermediates were isolated. In boiling hydrocarbon solvents reaction with 1,4-benzoquinones led chiefly to 1 : 1- addition. 2,2-Dialkoxy-2,3-dihydrobenzofurans were obtained. These stoichiometric adducts are evidently the source of 2-ethoxyfuran, lactone and quinonyl acetic acid derivatives observed in previous work.