Synthesis of 2- C-methyl- d-lyxode and 2- C-methyl- d-xylose

Abstract

The reaction of methyl 3,5- O-isopropylidene-β- d- threo-pentofuranosid-2-ulose ( 1) with methylmagnesium iodide or methyl-lithium gave methyl 3,5- O-isopropylidene-2- C-methyl-β- d-lyxofuranoside ( 3). Compound 1 reacted with diazomethane to give a spiro-epoxide that was reduced to yield 5, the C-2 epimer of 3. On the other hand, the anomer ( 2) of 1 reacted with methylmagnesium iodide or methyl-lithium to give methyl 3,5- O-isopropylidene-2- C-methyl-α- d-xylo- ( 6) and -lyxo-furanoside, respectively. The reaction of 2 with diazomethane and reduction of the resulting epoxides gave the same branched-chain sugars. Acid hydrolysis of 3 and 6 gave 2- C-methyl- d-lyxose and 2- C-methyl- d-xylose ( 14), respectively. Compound 14 was transformed into the 1,2:4,5-di- O-isopropylidene derivative. Some stereochemical aspects of the reactions are discussed.