Tetsuyoshi Takamoto

Direct formation of C-glycofuranosyl derivatives by the reaction of d-aldoses with nitromethane and methyl nitroacetate

Abstract Under appropriate conditions, condensation of d -ribose (1) with nitromethane afforded d -ribofuranosylnitromethanes (3 and 4) directly, in high yields. On the other hand, similar reactions of 5-deoxy- d -xylose (9) gave acyclic products (11), which were readily converted into the cyclized products (12 and 13) upon heating in water. Condensation of 9 with methyl nitroacetate, however, furnished a cyclic product (10) directly. The stereochemistry of the products is discussed on the basis of chemical reactions as well as instrumental data.

C-glycosyl derivatives in nitro sugar chemistry: Synthesis of D-ribofuranosylnitromethane derivatives and their epimerization under neutral conditions

Abstract The nitromethane condensation-product ( 3 ) from 2,3- O -isopropylidene- D -ribose ( 2 ) underwent dehydration and subsequent thermal cyclization in dimethyl sulfoxide to give a mixture of α- and β- D -ribofuranosylnitromethane derivatives ( 5 and 6 ) in a ratio of 7:2. Heating of 6- O -benzoyl-1-deoxy-1-nitro- D -altritol ( 10 ) in water afforded α- and β- C -glycosyl derivatives ( 11 and 12 ) in a ratio of 2:3. Pure 11 and 12 gave the same mixture of 11 and 12 when heated in water, and similar epimerization of the isopropylidene acetals 5 , 6 , 13 , and 14 proceeded readily upon heating, leading mainly to the thermodynamically more-stable α anomers.

Studies on nitro sugars : Part II. Synthesis of benzyl 3,5-DI-O-benzyl-2-deoxy-2-Nitro-α-D-xylofuranoside and its transglycosylation with alkali

Abstract Oxidation of benzyl 3,5-di- O -benzyl-2-oximino-α- D - threo -pentofuranoside ( 6 ) with trifluoroperoxyacetic acid afforded benzyl 3,5-di- O -benzyl-2-deoxy-2-nitro-α- D -xylofuranoside ( 8 ) in 83% yield. Transglycosylation of 8 to give the corresponding methyl xyloside ( 10 ) was achieved in alkaline methanol at room temperature, proceeding probably via an intermediate 2-nitroglycal ( 9 ). The structures of 8 and 10 were determined from their specific rotations and p.m.r. spectra.

Novel synthesis of γ-hydroxy-α-nitro-olefins

Treatment of α-unsubstituted αβ-epoxyketoximes with trifluoroperoxyacetic acid affords the corresponding γ-hydroxy-α-nitro-olefins in high yields.