The photochemistry of ketones derived from carbohydrates. Part IV. Photochemical additions of 2,3-dimethylbut-2-ene to 1,5-anhydrohex-enuloses

Abstract

Irradiation of 1,5-anhydro-4,6-O-benzylidene-1,2-dideoxy-D-threo-hex-1-en-3-ulose (1) in 2,3-dimethylbut-2-ene with u.v. light afforded three cyclobutane adducts, namely 1,5-anhydro-4,6-O-benzylidene-2-deoxy-1,2-C-tetramethylethylene-D-hex-3-ulose with the (1S)-xylo-(2). (1R)-xylo-(3), and (1R)-lyxo-(4) structures, and a dimer, for which structure (5b) or (5c) has been proposed. Similar treatment of the 1,5-anhydro-erythro-enulose derivative (9) also gave adducts, two of which [(10) and (11)] have been isolated and characterised as the (1S)-ribo- and (1R)-ribo-1,5-anhydro-D-hexulose derivatives.