Full acetals of β-d-glycopyranosylnitromethanes and a 1,2-dideoxy-1-nitroalk-1-enitol derived from common hexoses

Kinetically controlled O-isopropylidenation of common 2,6-anhydro-1-deoxy-1-nitroalditols (β-d-glycopyranosylnitromethanes) derived from d-glucose, d-galactose, and d-mannose with 2-methoxypropene in 1,2-dimethoxyethane catalyzed with 4-toluenesulfonic acid afforded high yields of 2,3;4,6-di-O-isopropylidene acetals. With d-mannose, the bisacetal was also obtained in quantitative yield by reaction with 2,2-dimethoxypropane. Mono-O-benzylidenation of the starting compounds with benzaldehyde dimethyl acetal followed by O-isopropylidenation led to 4,6-O-benzylidene-2,3-O-isopropylidene acetals having better solubilities in non-polar solvents than the di-O-isopropylidene acetals. Di-O-benzylidenation of β-d-mannopyranosylnitromethane gave both (endo-2,3):4,6- and (exo-2,3):4,6-di-O-benzylidene acetals. Transacetalation of 1-deoxy-1-nitro-d-mannitol with 2,2-dimethoxypropane followed by 2-O-acetylation and β-elimination of the acetoxy group afforded (E)-1,2-dideoxy-2,4:5,6-di-O-isopropylidene-1-nitro-d-arabino-hex-1 -enitol.