Competing 1,n-elimination reactions of 1-bromo-5-bromomethyl-6,6-dichlorobicyclo[3.1.0]hexane: A strained 1,3-bridged cyclopropene and a vinylcarbene as reactive intermediates

Article abstract of DOI:10.1016/0040-4020(96)00912-X

1-Bromo-5-bromomethyl-6,6-dichlorobicyclo[3.1.0]hexane (9) was treated with alkyllithium at different temperatures. After halogen metal exchange in 9, two competing 1,n-elimination reactions take place. A 1,2-elimination of organolithium compound 12 leads to strained 1,3-bridged cyclopropene 10 which undergoes a cyclopropene-vinylcarbene rearrangement to 17. Insertion of 17 into the ether solvent affords isomers 18a and 18b. In contrast, 1,4-eliminations of organolithium compound 13 generate butadienes 14 and 16, respectively. The formation of the products is temperature dependent.