REFUNCTIONALIZATION OF HOMOALLYLIC ALCOHOLS CONTAINING A VINYLIC CHLORINE ATOM

The chlorine atoms in Z-substituted vinyl chlorides 1, 5, 7 and 14 hav e been replaced by alkyl, vinyl and (trimethylsilyl)methyl groups to g ive the alkenes 3, 4, the dienes 9, 10, 15, or the allylsilanes 8. The latter have been transformed stereoselectively into tri- and tetrasub stituted tetrahydrofurans 18 and 20. The vinyl chlorides 1 have been c onverted into the corresponding Z-vinylsilanes 13 and 23. These serve as starting compounds for the stereoselective generation of trisubstit uted 5,6-dihydro-2H-pyrans 25, 26, 28, and 30. Derivatives 31 and 34 o f the vinyl chlorides 1 have been subjected to stereoselective free-ra dical cyclizations giving substituted tetrahydropyrans 33 and 35, The vinyl chlorides 1 may readily be converted to the alkynes 37.