Show the formation of the structures in 5 that result from the NaBH4 reduction using Haworth structures.
Show how the "facile displacement of the hydrazine from 6 (ref. 14) is accomplished to give 3,4-di-O-benzyl-L-gulopyranose.
Communications transformations. Therefore, while syntheses of L-gulose have Synthesis of L-Gulose from D-Glucose via none of these was suitable for our purposes; Aldose Interehange been reported, we report herein an efficientsynthesis of an appropriate Summary: L-Gulose has been prepared from D-gl ucose in gulose derivative. a form suitable for reconstruction of bleomycin. Fischer recognized the conceptually simple relationship between the readily available D-glucose and L-gulose, which Sir: Bleomycin (1) is an antitumor antibiotic possessing differ only in oxidation state at C-1 and C-6, and utilized this clinically useful activity in the treatment of squamous cell of L-gulose from D-glucaric acid principle for the preparation carcinomas. Our interest in the total synthesis of bleomycin in low yield by successive reductions with sodium amalg B2 (1) has prompted us to consider practical methods for In the present case, more direct interconversion has been achieved by oxidation of 1,2-di-O-ace tyl-3,4-di-0-benzyl ding 6-aldehydo sugar D-glucopyranose (3b) to the correspon lisolated as the respective N,N-dimethylhydrazone (4)] and subsequent borohydride reduction of the latent dialdehyde with sodium borohydride, affording the desired 3,4 di o benzyl-1-(NN-dime thylhydrazino)-L-gulopyranose (5) as a clear oil in 42% overall yield from D-glucose, Verification of plished by conversion to 1,6-anhydro structure was accom preparation of the rare sugar L-gulose in a form suitable for synthetic elaboration of the carbohydrate moiety of bleomy a R.R.COCHs cin. Since gulose must be attached stereoselectively to L- erythro-3-hydroxyhistidine and 3-0-carbamoylmannose via 0-1 and 0.2, respectively, the sugar must be prepared in a form that permits O-1 and 0-2 to be differentiated from each other, and from O-3, 0-4, and 0-6, ubsequent NICHNe CHO HO OH OH HO D-glucose L-gulose
