Methylation of nitro sugars with diazomethane, and preparation of some new amino sugar methyl ethers

Abstract

Diazomethane reacted with methyl 3,6-dideoxy-3-nitro-α- l-glucopyranoside ( 1) under catalysis by boron trifluoride to give the 2- O-methyl and the 2,4-di- O-methyl derivative ( 2 and 3). Similarly, the 4-acetate ( 4) of 1 afforded the 4-acetate ( 5) of 2. Boron trifluoride-catalyzed acetylation of 2 at about −60° gave 5 whereas, at 0°, acetolysis took place producing 1,4-di- O-acetyl-3,6-dideoxy-2- O-methyl-3-nitro-α- l-glucopyranose ( 6). Diazomethane treatment of methyl 3,4,6-trideoxy-3-nitro-α- l- erythro- and -α- l- threo-hex-3-enopyranosides 7 and 8 furnished the corresponding 2- O-methyl derivatives 9 and 10. With triphenylphosphine and carbon tetrachloride, 2 yielded methyl 4-chloro-3,4,6-trideoxy-2- O-methyl-3-nitro-α- l-galactopyranoside ( 11) which was dehydrochlorinated to 9. Borohydride reduction of 9 gave methyl 3,4,6-trideoxy-2- O-methyl-3-nitro-α- l- xylo-hexopyranoside ( 12). Catalytic hydrogenation of 3 and 12 afforded the corresponding amino sugar hydrochlorides 13 and 15. Treatment of 5 with ammonia gave a 4-amino-3-nitro glycoside (isolated as the hydrochloride 17) hydrogenation of which led to methyl 3,4-diamino-3,4,6-trideoxy-2- O-methyl-α- l-glucopyranoside dihydrochloride ( 19). The N-acetyl derivatives ( 14, 16, 18, and 20) of the four new amino sugars were prepared.