Cyclopentenone Synthesis from 1,1-Dichloroallyllithium-Ketone Adducts as Well as from Dichlorocarbene-Allyl Alcohol Adducts

Article abstract of DOI:10.1246/bcsj.53.1010

Treatment of (3,3-dialkyl-2,2-dichlorocyclopropyl)methanols with hydrobromic acid gives 2-cyclopentenones through postulated intermediates, 3-chlorocyclopentadienyl cations.Another method which should give the same cationic intermediates involves trifluoroacetic acid catalyzed reaction of 3,3-dichloro-1-alken-4-ols.This is found to be particularly useful for cyclopentenone annulation.