Total synthesis of the naturally occurring endothelin converting enzyme (ECE) inhibitor WS 75624 A

The ECE inhibitor WS 75624 A (1a) was synthesized following a convergent strategy. 2,4-Dibromothiazole (2) served as the central building block, which underwent consecutive cross-coupling reactions. In the first C-C bond formation step, it was substituted at carbon atom C-2 by a C₇-alkylzinc chloride derived from iodide 8 (85% yield). In the second step, the intermediate 4-bromothiazole 9 was converted to the corresponding stannane 10 which was coupled at carbon atom C-4 to the 2-iodopyridine 6 (75% yield).