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In recent years heterogeneous catalysts have attracted a great attention due to efficiency, economic and environmental considerations. HY-zeolite is an important heterogeneous catalyst used in various chemical transformations, such as liquid phase acylation of amines,2) direct conversion of aldehydes into nitriles and ketones into amides, 3) selective removal of N-Boc protecting group from aromatic amines 4) and one-pot synthesis of 2,3-dihydro-2,2-dimethylbenzofurans. 5)Thus the remarkable catalytic activity together with easy availability, operational simplicity and recoverability of HYzeolite encouraged us to utilize this catalyst for the synthesis of polyhydroquinolines having 1,4-dihydropyridine moiety.1,4-Dihydropyridines exhibit a variety of biological properties. They can cure the disordered heart ratio as a chaincutting agent of factor IV channel and also possess the calcium channel agonist-antagonist modulation activities. [6][7][8] These compounds also behave as neuroprotectants, cerebral antiischaemic agents and chemosensitizers. 9,10) 1,4-Dihydropyridines were synthesized more than a century ago by Hantzsch by heating a mixture of an aldehyde, a b-ketoester and ammonia in ethanol under reflux for several hours.11) Different other heating approaches for the syntheses of polyhydroquinoline derivatives have subsequently been reported.12-16) However, these methods require drastic reaction conditions and long reaction times. Recently microwave irradiation has also been applied for the preparation of polyhydroquinolines.17) Yb(OTf) 3 18) or iodine 19) have been found to catalyze the Hantzsch reaction at ambient temperature but using the first catalyst the times required for the conversions were 2-8 h while using the second catalyst at room temperature the time of conversions was 1.5-6 h. The second catalyst should also properly be removed from the reaction mixture during work-up.In continuation of our work [20][21][22][23][24] on the applications of heterogeneous catalysts on organic transformations we report here a convenient and efficient method for the synthesis of polyhydroquinolines (containing 1,4-dihydropyridine moiety) using HY-zeolite as a catalyst. Four-component coupling reactions of aldehydes, ethyl acetoacetate, dimedone and ammonium acetate were carried out using this catalyst at room temperature (Chart 1).A series of polyhydroquinoline derivatives were prepared following the above method using various aldehydes (Table 1). Both aromatic and aliphatic aldehydes underwent the conversion smoothly. Aromatic aldehydes containing electron donating as well as electron withdrawing groups worked well. The aryl moiety having different groups or the same group at different positions did not show much differences in the yields of the products. Heterocyclic aldehyde like furfural also underwent the facile transformation. The polyhydroquinoline derivatives were formed within 2.0-2.5 h at room temperature in excellent yields (87-93%). In absence of the catalyst no product could be detected within 3 h at r...

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