Van den Hoven BG, Alper H. Remarkable synthesis of 2-(Z)-6-(E)-4H-[1,4]-thiazepin-5-ones by zwitteronic rhodium-catalyzed chemo- and regioselective cyclohyrocarbonylative ring expansion of acetylenic thiazoles.
J Am Chem Soc 2001;
123:1017-22. [PMID:
11456654 DOI:
10.1021/ja003085c]
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Abstract
Cyclohydrocarbonylative ring expansion of acetylenic thiazoles in the presence of CO, H(2), and catalytic quantities of the zwitterionic rhodium complex (eta(6)-C(6)H(5)BPh(3))(-)Rh(+)(1,5-COD) and triphenyl phosphite affords thiazepinones in 61 to 90% yields. This novel transformation of a 5- to a 7-membered heterocycle is readily applied to acetylenic thiazoles containing hydro, alkyl, alkyl halide, vinyl, and benzo substitutents in positions 4 and 5 of the thiazole ring in addition to alkyl-, ether-, ester-, vinyl-, and aryl-substituted alkynes at position 2.
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