Treatment of a solution at-10 to-5'of I-(N-nitrosoacety1amino) cyclohexanol in pentane containing an olefin and a tetraalkylammonium chloride with 50% sodium hydroxide initiates a series of reactions which results in the formation of cyclohexylidene carbene. The latter is trapped by olefins to yield unsaturated cyclopropane compounds in higher yields than were previously obtained by starting with N-nitrosooxazolidones under various conditions.