title: 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.
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.
authors.affiliation: Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie Curie St., Ottawa, Ontario, Canada K1N 6N5.
authors.forename: B G
authors.initials: BG
authors.lastname: Van den Hoven
authors.forename: H
authors.initials: H
authors.lastname: Alper