Alkaline Epoxidation of Carbohydrate Nitroolefins

Abstract

Action of hydrogen peroxide in a weakly alkaline medium upon nitroolefinic sugar derivatives led to α-nitroepoxides in excellent yields. Thus, methyl 4,6-O-benzylidene-2,3-dideoxy-3-nitro-α-D-erythro-hex-2-enopyranoside (1), its β-anomer 2, and its α-D-threo epimer 3 stereospecifically gave methyl 2,3-anhydro-4,6-O-benzylidene-3-C-nitro-α-D-mannopyranoside (6), the β-D-allo isomer 7, and the α-D-talo isomer 8, respectively. The corresponding β-D-threo olefin 4 produced a mixture of the β-D-gulo (9) and β-D-talo (10) epoxides, with 9 strongly preponderating. The β-D-gulo (11) and β-D-talo (12) derivatives were made from the enantiomer 5 of 4. Another route to α-nitroepoxides, originating from 3-bromo-3-deoxy-3-nitro sugars, furnished the β-D-manno isomer 13.