THE QUASI-HOMO-ANOMERIC INTERACTION IN SUBSTITUTED TETRAHYDROPYRANYL RADICALS - STRUCTURE AND KINETICS OF FORMATION

The EPR spectra of 3-acyloxytetrahydropyran-2-yl radicals (8 and 9) in dicate that these species preferentially adopt conformations in which the orientation of the eater group allows maximum overlap between the SOMO, the lone pair on the ring oxygen, and the sigma orbital of the C-O bond. These observations support earlier proposals that the same t ype of stabilising interaction affects the conformations of more compl ex glycosyl radicals. The rates of formation of 7 and 8 from the corre sponding aryl sulfides are affected by this ''quasi-homo-anomeric'' in teraction. (C) 1998 Elsevier Science Ltd. All rights reserved.