Carbonylation of vinyl halides with carbonylcobalt

Abstract

The reactions of both (E)-β-bromostyrene (E)-(1a) and its Z-isomer (Z)-(1a) with octacarbonyldicobalt in the presence of methyl iodide and calcium hydroxide at 20 °C in dioxane-water under carbon monoxide (1 atm) gave (E)-cinnamic acid (E)-(2a) exclusively. In contrast, with (E)-1-bromo-2-phenylpropene (E)-(1b), the thermodynamically less stable (Z)-3-phenylbut-2-enoic acid (Z)-(2b) was obtained as the major product together with the (E)-isomer (E)-(2b). The carbonylation of 3-chloroprop-2-enols (7a–f) gave the corresponding furan-2(5H)-ones (8a–f) in good yield.