Reaction of dicobalt octacarbonyl with acetylene and carbon monoxide at low temperature and pressure: Formation of cyclic enone products

Dicobalt octacarbonyl is shown to react with acetylene and carbon monoxide under mild conditions in dimethoxyethane or benzene to produce, in low yields, bicyclo3.3.0]octa-3,7-diene-2,6-dione, benzoquinone, and the cyclopentadienone-derived products 3a,4,7,7a-tetrahydro-2,7-methanoindene-1,10-dione, 1-indanone, tetracyclo5.5.2.0^2,60^8,12]tetradeca-4,10,13-triene-3,9-dione, and tetracyclo5.5.2.0^2,60^8,12]tetradeca-4,9,13-triene-3,11-dione. Possible mechanisms for the formation of these products are discussed.