Reaction of Triplet Carbonyl Carbene with Olefins

Article abstract of DOI:10.1021/jo00197a033

The gas-phase reaction of C2O(³Σ) with 2,3-dimethyl-2-butene produces 1,1,2,2,6,6,7,7-octamethyldispiro<2.1.2.1>octane-4,8-dione and 2,2,3,3-tetramethylcyclopropanecarboxylic acid as major products rather than the allenic product characteristic of the reaction with simpler substrates.The positive identification of these molecules provides strong evidence for prior formation of the previously postulated cyclopropylideneketene.Further, the rate-determining step for reaction of C2O(³Σ) with the substrate cannot be elimination of CO as has been postulated on the basis of calculations.