C-Branched Glycals as Monosaccharidic Push-Pull Butadienes

Treatment of 2(3)-formyl-glycals 1, 3, 5 with alkyl cyanoacetates afforded 2(3)-[(E)-2-cyano-2- alkoxycarbonyl-vinyl]-2(3)-deoxy-1,5(2, 6)-anhydro-hex-1(2)-enitols 2, 4, 6 which were reacted with aniline to yield nicotinonitrile acyclo-C-nucleosides 7, 9. Nicotinic acid ester acylo-C-nucleosides 11 were obtained by the reaction of 2,6-anhydro-1,4,5-tri-O-benzyl-3-[(E)-2-cyano-2-alkoxycarbonylvinyl]- 3-deoxy-D-erythro-hex-2-enitols 6 with ammonia.