Direct C-2 arylation of alkyl 4-thiazolecarboxylates: New insights in synthesis of heterocyclic core of thiopeptide antibiotics

The Pd(0)-catalyzed regioselective C-2 (hetero)arylation of tert-butyl 4-thiazolecarboxylate with a broad (hetero)aryl halide is reported, including the direct coupling of pyridinyl halides. The process has allowed the preparation of valuable 2-pyridynyl-4-thiazolecarboxylates which are components of the complex heterocyclic core of thiopeptides antibiotics. As a first application, a synthesis of a tert-butyl sulfomycinamate thio-analogue from tert-butyl 4-thiazolecarboxylate is here described through a three-step direct pyridinylation, halogenation, and Stille cross-coupling sequence.