ELECTROPHILIC CYCLIZATION REACTION OF gem-DIFLUOROOLEFIN DERIVATIVES : SYNTHESES OF 6, 6-DIFLUOROTETRAHYDRO-2-PYRONES AND 2, 2-DIFLUOROTETRAHYDROPYRAN via HALOGEN INDUCED CYCLIZATION

Abstract

The halocyclization reactions of gem-difluoroolefin derivatives (4, 5 and 8) with iodine in acetonitrile proceed in the 6-endo mode selectively providing 6, 6-difluorotetrahydro-2-pyrones (9) and 2, 2-difluorotetrahydropyran (10), respectively.