Generation of bicyclo[4.1.0]heptatrienes. Carbene-carbene rearrangements in solution.

Eliminations Involving Carbon–Halogen Bonds and Leading to Highly Strained Rings

“…Thus, in the case of 2,2-dimethyl-1,1-dihalocyclopropanes ring-opening occurs to give enynes and, in some cases, to produce allenic carbenes: 64 Both types of product are thought to arise through an initially formed cyclopropene. The formation of enynes has been rationalized in terms of a 1,4-dehydrohalogenation coupled to ring-opening as in 11, while the allene is apparently derived by trapping of the allenic carbene derived by 1,2-dehydrohalogenation as in 12.…”

Dehydrohalogenation of adducts of dichlorocarbene with cyclooctene and its peripherally cyclopropanated analogs

“…It is known that under conditions of dehydrohalogenation (a strong base in a polar solvent) the latter compounds initially form highly reactive cyelopropenes, which often add nucleophiles under the reaction conditions 6-8 or appear to be unstable and undergo further conversions, namely, exo isomedzation of the cyclopropene double bond 9,1~ or rearrangements. [10][11][12][13] It is known l~ that dehydrochlorination of 9,9-dichlorobieyclo[6.1.0]nonane under the action of potassium tert-butoxide in dimethyl sulfoxide affords bicycle[6.1.01nona-1,6-diene. We considered the results of this reaction, which seem to be very interesting.…”