Rhodium carbonyl-catalyzed carbonylation of unsaturated compounds III*. Synthesis of α,β-unsaturated ethyl ketones by cross-hydrocarbonylation of acetylenes and ethylene with carbon monoxide and hydrogen

Article abstract of DOI:10.1016/0022-328X(87)80044-X

Rhodium carbonyl-catalyzed cross-hydrocarbonylation of acetylenes and ethylene with carbon monoxide and hydrogen gives α,β-unsaturated ethyl ketones.Under CO (10 kg cm^-2) and H2 (50 kg cm^-2) at 90 deg C the reaction of diphenylacetylene with ethylene in the presence of Rh4(CO)12 catalyst gave (E)-1,2-diphenyl-1-penten-3-one (3a) in 91percent yield.Under similar conditions phenylacetylene (1d), 1-hexyne (1e), 3,3-dimethyl-1-butyne (1f), and trimethylsilylacetylene (1g) gave (E)-1-phenyl-1-penten-3-one (3d), (E)-4-nonen-3-one (3e), (E)-6,6-dimethyl-4-hepten-3-one (3f), and (E)-1-trimethylsilyl-1-penten-3-one (3g) in 76, 68, 93, and 62percent respectively.Thus, the reaction of terminal acetylenes proceeds with high stereo- and regioselectivity: the propionyl group is introduced to the less-sterically hindered acetylenic carbon atom.By comparison of the regioselectivity with that in the formation of 5-ethyl-2-(5H)-furanone (2), which is obtained in the presence of a hydrogen donor such as alcohol, these reactions are assumed to include a β-acylvinylrhodium complex as the common key intermediate.