3,4-dioxythiophene derivatives

摘要

A process for the production of 3,4-dioxythiophene compounds represented by the following formula (I), is described. In formula (I) A, B, C and D in each case independently denote a bond, optionally substituted alkylene, optionally substituted cycloalkylene, optionally substituted arylene or (O-(CR¹R²)_m)_x, where R¹ and R² in each case mutually independently denote hydrogen or optionally substituted alkyl, m denotes an integer from 1 to 10 and x denotes an integer from 1 to 10, provided that at least one of the units A, B, C or D does not denote a bond. The process involves reacting a 3,4-dihydroxythiophene or the alkali metal salt thereof with the following compound, TosO-A-B-C-D-OTos, thus forming an intermediate 3,4-dioxythiophene diester. The intermediate 3,4-dioxythiophene diester is saponified, thus forming an intermediate 3,4-dioxythiophene dicarboxylic acid, which is then decarboxylated, thereby forming the 3,4-dioxythiophene compound represented by formula-(I).