Regioselective chlorination of 6-(5-methyl-2-oxo-4-imidazolin-4-yl)-6-oxohexanoic acid ethyl ester: A new synthesis of biotin

Abstract

Regioselective chlorination of a methyl group in 6-(5-methyl-2-oxo-4-imidazolin-4-yl)-6-oxohexanoic acid ethyl ester via reaction with sulfuryl chloride in methylene chloride has been performed for the first time. The synthesis of 5-(2-oxo-2,3-dihydro-1H-thieno[3,4-d]imidazol-4-yl)pentanoic acid methyl and ethyl esters (tetradehydrobiotin esters) — key compounds in biotin (vitamin H) synthesis — has been developed proceeding from 6-(2-oxo-5-chloromethyl-4-imidazolin-4-yl)-6-oxohexanoic acid ester.