Regioselective Cross-Coupling Reactions as an Entry into Biologically Relevant Bithiazoles: First Total Synthesis of Cystothiazole E.

Abstract

No problems have been encountered while using bithiazoles in Pd-catalyzed cross-coupling reactions. It was thus possible to achieve the first synthesis of cystothiazole E (1) with a Suzuki coupling of the building blocks 2 and 3 as the pivotal C-C bond-formation step (94 % yield, TBDMS=tBuMe2 Si). The bithiazole 3 could be prepared very conveniently from 2,4-dibromothiazole by regioselective cross-coupling reactions.