The dihydro-pyridine ring in the title compound, C(25)H(31)NO(4), adopts an envelope conformation with the methine C atom representing the flap. The cyclo-hexenone rings also adopt envelope conformations with the C atoms bearing the methyl C atoms representing the flaps. The phenolic hy-droxy group forms an intra-molecular hydrogen bond to one of the two keto O atoms. The hy-droxy group of the N-bonded alkyl chain forms an inter-molecular hydrogen bond to the other keto O atom of an adjacent mol-ecule. The latter hydrogen bond leads to the formation of a helical chain running along the b axis.

We report an unprecedented multicomponent reaction of acetoacetanilide with malononitrile leading to a structurally novel bicyclic product (9) in a high yield. The structure has been confirmed by X-ray crystallography and comparative Hirshfeld surface analysis of 5-cyano-2-hydroxy-2-methyl-N-phenyl-4-(yridine-4-yl)-6-(thiophen-2-yl)-3,4-dihydro-2H-pyran-3-carboxamide 2, 5-cyano-2-hydroxy-2-methyl-6-oxo-N-phenyl-4-(thiophen-2-yl)piperidine-3-carboxamide 4 and 2-(8-amino-7,8a-dicyano-1-imino-4a-methyl-3-oxo-2-phenyl-1,3,4,4a,5,8a-hexahydroisoquinolin-6(2H)-ylidene)-N-phenylacetamide 9.

Microwave irradiation of three component reaction of dimedone, appropriate aromatic aldehydes and amino alcohols in a stoichiometrical ratio 2:1:1 for few minutes afforded the formation of a stable fused three membered ring of the corresponding 3,6,6-tetramethyl-2,3,4,5,6,7,8,9,10-decahydroacridine-1,8-dione derivatives in an excellent yield (80–91%). The structure of all products has been characterized by X-ray crystal structural analyses, 13C NMR, 1H NMR, IR and mass spectrum analyses