Ring transformations of pentose glycals with push-pull butadiene functionality

2-Formyl-D-xylal (1a) and 2-formyl-L-arabinal (1b) were reacted with alkyl cyanoacetates to furnish the 1,5-anhydro3,4-di-O-benzyl-2-[(E)-2-cyano-2-alkoxycarbonylvinyl]-2-deoxy- D(L)-hex-1-enitols 2a and 2b, respectively. Treatment of 2a, 2b with aromatic amines afforded the 1-aryl-5-[1,2-bis(benzyloxy)-3hydroxypropyl]-1,2-dihydro-2-oxopyridiiie-3-carbonitriles 3a-C. Ring transformation of la, lb with N-substituted oxobutyramides, dialkyl 3-oxopentanedioate and benzimidazol-2-ylacetonitrile yielded the 3-acetyl-1-aryl-5-[1,2-bis(benzyloxy)-3-hydroxypropyl]-1,2-dihydropyridin-2-ones 6a-d, alkyl 5-[1,2-bis(benzyloxy)3-hydroxypropyl]-2-hydroxyisophthalates 8a-d and 2-[1, 2-bis(benzyloxy)-3-hydroxypropyl]benzo[4,5]imidazo-[1,2-a]-pyri- dine-4-carbonitriles 11a, 11b, respectively.