摘要:
The nitroalkene, methyl 5,6-dideoxy-2,3-O-isopropylidene-6-nitro-6-(phenylthio)-beta-D-ribo-hex-5(Z)-enofuranoside (1), was found to react with nucleophiles to give, on ozonolysis, the corresponding phenyl thiolesters 3, 5, 6a-c, and 7 bearing the nucleophilic residue alpha to the carbonyl group. The nucleophiles Me3SiOK, NaOMe, NaOCH2Ph, and TsNHK all stereoselectively (7:1-50:1) reacted to give products with the allo-thiouronate configuration. In contrast, potassium succinimide and phthalimide, nucleophiles with aerofoil bulk, gave substituted talo-thiouronates (> 15:1).