Pyran and Pyridine as Building Blocks in Heterocyclic Synthesis

Abstract

ABSTRACT. The present work is devoted to study the interaction of β-aroylacrylic acid derivative (3) with malononitrile in (DMF) in the presence of piperidine and/or ammonium acetate, then using the formed compounds as starting materials for synthesizing fused and isolated heterocyclic systems. It has been established that the β-aroylacrylic acid (3) reacts with malononitrile in (DMF) in the presence of piperidine as a catalyst with the formation of 4H-pyran derivative (4). By changing the catalyst into ammonium acetate, pyridine derivative (5) has been obtained. Also the N-maleamic acid derivatives (19) and (27) have been synthesized via the interaction of (4) and (5) with maleic anhydride. The purpose of this step is to study the behavior of the formed maleamic acid derivatives -as analogies of β-aroylacrylic acids -towards different active methylene compounds under Michael addition reaction.

2- (3, 4- Dimethylphenyl - 3- [3, 4-Dichloro (or 3, 4-Dimethyl) Benzoyl])-Propanoic Acids as Precursors in the Synthesis of Some Heterocyclic Compounds

“…Further support for the assigned structure of 15 was gained from the 1 H NMR revealed at = 6, doublet signals correlated with olefinic proton which is in accordance with structure 15 of the appearance of extra multiplet signals at 3.7-4.2 corresponding to (CH 2 -CH) moiety and singlet at 11.2 corresponding to (OH groups) confirm that oxime 14 exiss. The present work also reports on the behaviour of acid 3a towards malononitrile in the presence of ammonium acetate as catalyst (25) on boiling water bath,t didnot give the expected product, 2-amino-3-cyano carboxy-6-(3,4-dimethyl)phenyl-3,4-dihydropyridine 16 but it gave a yellow crystal of 2-amino-3-cyano-4-carboxy-6-(2,4-dimethyl) phenyl pyridine 17 and colourless crystal of 2-amino-3-cyano-4-carboxy-6-(2,4-dimethyl)phenyl-1,2,3,4-hydropyridine18.…”