SYNTHESIS AND STRUCTURAL STUDY OF SEMICARBAZONE-CONTAINING 1,4-DIHYDROPYRIDINE

摘要

A new series of 1,4-dihydropyridines (1,4-DHPs) bearing a semicarbazone moiety on C5 (8a-g) have been synthesized from suitably functionalized 1,4-DHPs (2) and semicarbazide.Compounds (8a-g) did not cyclize to the respective seven member ring though this is a favoured 7-endo-trig process.Geometrical and structural features determined by theoretical,DFT (B3LYP/6-31G*) and experimental (X-Ray diffraction) data,reveal the presence of a low energy stereoisomer,namely (E) s-trans,which is also present in solution according to NOe experiments carried out on compound (8a).These geometrical findings account for the lack of cyclization of compounds (8a-g),and reveal that they meet the structural requirements needed for biological activity as calcium-channel modulators.