The Gas-Phase Photolysis of Perfluoro α-Diazo Ketones: Furan Formation and the Involvement of Transient Oxirenes

Article abstract of DOI:10.1021/jo00389a009

The gas-phase photolyses of hexafluoro-3-diazo-2-butanone (1), octafluoro-2-diazo-3-pentanone (2), and octafluoro-3-diazo-2-pentanone (3) have been studied.Chemical trapping experiments with hexafluoro-2-butyne provide evidence that isomeric ketocarbene intermediates equilibrate, presumably via transient 4-?-electron oxirenes. 1 yields tetrakis(trifluoromethyl)furan (8) as a major product, with a trace of 1,2,3-tris(trifluoromethyl)-3-(trifluoroacetyl)cyclopropene (9) and bis(trifluoromethyl)ketene (10).Photolysis of either 2 or 3 yields the same four trapped products: 2-(pentafluoroethyl)-3,4,5-tris(trifluoromethyl)furan (12), 3-(pentafluoroethyl)-2,4,5-tris(trifluoromethyl)furan (14), 1,2,3-tris(trifluoromethyl)-3-(pentafluoropropionyl)cyclopropene (13), and 1,2-bis(trifluoromethyl)-3-(pentafluoroethyl)-3-(trifluoroacetyl)cyclopropene (15), in approximately the same ratio, along with the Wolff rearrangement product, (pentafluoroethyl)(trifluoromethyl)ketene (16).