Cyclopent-2-enones acetylene derivs

A mixture of propylene oxide, (trimethylsilyl)manganese pentacarbonyl, and methyl acrylate in ether allowed to react for 24-96 h in a polypropylene syringe pressurized at 5 kbar intermediate siloxymanganese carbonyl complex (Y 82%), in acetonitrile irradiated (350 nm) at room temp, for 1-12 h, then hydrolyzed with water product (Y 53%). Acetylene derivs. furnished enones which were converted to cyclopent-2-enones. F.e. and stereoselectivity s. P. DeShong, D.R. Sidler, J. Org. Chem. 53, 4892-4 (1988). 

A similar synthesis starts from commercially available 1,5-hexadiyne and 2-methyl-cyclopent-2-enone. The benzocyclobutene is obtained from a bis-acetylene in a cobalt-catalyzed reaction. It rearranges regio- and stereoselectively to a 3-deoxy steroid derivative. The overall yield from the cyclopentenone was 40% (R.L. Funk, 1977). 

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See also in sourсe #XX -- [ , ]

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