Preparation and Structures of Acetylene Adducts of 4,6-O-Isopropylidene- and 4-O-Acetyl-6-O-triphenylmethyl-1,5-anhydro-2-deoxy-D-erythro-hex-1-en-3-uloses

Cyclobutene adducts were formed stereoselectively in good yields by the irradiation of acetone solutions of 4,6-O-isopropylidene- and 4-O-acetyl-6-O-triphenylmethyl-1,5-anhydro-2-deoxy-D-erythro-hex-1-en-3-uloses, derived from D-glucal triacetate, in the presence of acetylene. The stereochemistry at the ring junction was achieved by a single-crystal X-ray analysis and a chemical correlation with the derived compounds.