Photochemistry of carbohydrate derivatives. Part I. Photolytic decomposition of glucopyranosyl phenyl sulphone acetates

Abstract

U.v. irradiation of either 2,3,4,6-tetra-O-acetyl-β-D-glucosyl phenyl sulphone or its α-anomer in benzene gave sulphur dioxide, biphenyl, the 2,3,4,6-tetra-O-acetyl derivatives of 1,5-anhydro-D-glucitol (6), α-D- and β-D-glucosylbiphenyl [(3) and (4)], and αβ-D-glucosylbenzene, and 1,3,4,5,8,9,10,12-octa-O-acetyl-2,6:7,11-dianhydro-D-gluco-L-altro-L-erythro-dodecitol, which can be considered as a 1-deoxy-derivative of αβ-D-trehalose octa-acetate.

The part played by the solvent in product formation was determined from the reaction in hexadeuteriobenzene. This gave pentadeuteriobiphenyl, compounds (3) and (4) tetradeuteriated in their aromatic residues, and 50% of compounds (6) deuteriated at C-1, preponderantly in the axial position.

A mechanism involving an intermediate carbonium ion has been excluded since irradiation in the presence of methanol gave no methyl glucosides. A free-radical mechanism is proposed, which accommodates all the products and accounts for the deuterium content of those formed in hexadeuteriated benzene.