The preparation and pentannulation reactions of 1-(phenylthio)-, 1-(methy1thio)-and 1- (isopropylthio)-cyclopropylphosphonium fluoborates are described. As part of a synthetic approach to portulal, a plant-growth regulator, 2-(carbomethoxy)-4-methylcyclohept-4-en-l- one is converted to its bicyclo [5.3. 0] decenone derivative. This annulation reaction illustrates the synthetic application and limitations of the 1-thio-substituted ...
