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To facilitate the synthesis of the carbohydrate moiety of bleomycin [2-0-(3-0-carbamoyl-a-~-manno-pyranosy1)-~-gulopyranose] and its subsequent attachment to the remainder of the bleomycin molecule in a regioand stereoselective fashion, a number of suitably protected gulose derivatives were prepared and their chemistry was studied. Key intermediates included 1,6-anhydro-3,4-di-0-benzyl-~-~-gulopyranose (12), 1,6-di-O-acetyl-3,4-di-O-benzyl-P-~-gulopyranose (24), benzyl 3,4,6-tri-O-benzyl-P-~-gulopyranoside (27), and 3,4-di-O-benzyl-1,6-dideoxy-1,6-(l-hydrazinyl-2-ylidene)-~-~-glucodialdehydo-l,5-pyranose (28).Accordingly, D-glucose was converted to the known triacetyl ortho ester derivative 2 (Scheme II).4 Deacety-(1) (a) Hecht, S. Katano et al. Scheme 11" D-glucose --_ + ACO& AcO I I x OEt ' 3 , R = H 4 , R = T r 5. R = l r 6 , R = H 9 90 10 X Z I 12 Results and Discussion T h e photocycloaddition reaction between sulfolene la and 2-cyclohexenone 2a afforded photoadduct 3a in a low yield (23%) together with t h e previously reported4 head-(3) The preliminary results reported by Williams and Lin (Williams, J. R.; Lin, C. J. Chem. Soc., Chem. Commun. 1981,752) should be revised in light of the complete experimental data reported herein.

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