Carbon radicals from allyl O-(trimethylsilyl)-alpha-bromo-alpha,alpha-difluoroacetal can cyclize onto the olefinic part regiospecifically to give gamma-lactols in good yield. The lactols are then converted to the corresponding alpha,alpha-difluoro-gamma-lactones. Systematic synthesis of multifluorinated-alpha,alpha-difluoro-gamma-lactones has thus been accomplished through intramolecular radical cyclization as a key reaction. Semiempirical MO calculation study suggested a unique nature of alpha,alpha-difluoroacetate in that complete delocalization of the electrons in the SOMO orbital of alpha,alpha-difluoroacetyl radical occurred; this caused unsuccessful cyclization. To apply the present radical reaction, the first synthesis of both enantiomers of difluoroeldanolide, analogues of the sex pheromone of the male African sugarcane borer, has been demonstrated. Electrophysiological tests revealed that the difluorinated analogues were as active as the natural eldanolide on the olfactory receptors.

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2000 halogen compounds halogen compounds (acyclic compounds) P 0030 36 -064 Synthesis of Optically Active Partly gem-Difluorinated Allylic Alcohols via [2,3]-Wittig Rearrangements and Lipase-Catalyzed Reaction. -[2,3]-Wittig rearrangement of 1,1,2-trifluoroallylic ethers (I) gives novel dienols. Lipase-catalyzed resolution of their acetates (V) and (VI) is successful in the case of the latter substrate. -(ITOH, TOSHIYUKI; KUDO,