Production of thiophene-2,5-dicarboxylic acid diesters, tetrahydrothiophene-2,5-dicarboxylic acid diesters and dibenzoxazolylthiophenes

Abstract

A method of producing a dibenzoxazolyl thiophene represented by the formula ##STR1## wherein R"' represents a hydrogen, an alkyl of 1-8 carbons, a cycloalkyl, a phenyl, a substituted phenyl or a benzyl, which includes: reacting a thiophene-2,5-dicarboxylic acid diester represented by the formula ##STR2## wherein R' represents a branched alkyl of 3-5 carbons, phenyl, or tolyl, with an aminophenol represented by the formula ##STR3## wherein R"' is the same as before, in the presence of an acid catalyst, wherein the acid catalyst is boric acid, phosphoric acid, polyphosphoric acid, zinc chloride, ferric chloride, or sulfuric acid.

Dependencies are inferred from the claim text.