Application of protease-catalyzed regioselective esterification in synthesis of 6'-deoxy-6'-fluoro- and 6-deoxy-6-fluorolactosides

Abstract

Subtilisin-catalyzed esterification of methyl 4-O-β-D-galactopyranosyl-β-D-glucopyranoside (methyl β-lactoside) (1) with 2,2,2-trichloroethyl butyrate (3) distinguished between the two primary hydroxyl groups of 1, yielding exclusively the 6'-O-monobutyryl derivative 6 from which 6'-deoxy-6'-fluoro- and 6-deoxy-6-fluorolactosides (22 and 29, respectively) were efficiently synthesized. A key feature in the synthesis of 22 was the use of the 2,4,6-trimethylbenzoyl (mesitoyl) group to protect the remaining free hydroxyl groups