Molecular iodine efficiently catalyzes the reaction of beta-naphthol and araldehydes on a preheated hot plate at 90-95 degrees C to give biologically active aryl-14H-dibenzo[a, j]xanthenes under solvent-free condition. The yields are excellent and the reactions go to completion within 15-20 min.

An efficient synthesis of a novel series of twelve substituted 2-amino-3-cyano-4H-pyran derivatives was achieved by a one-pot three-component cyclocondensation reaction of heteroaryl aldehydes, malononitrile and active methylene compounds catalyzed by iodine in aqueous medium under ultrasound irradiation. In comparison with conventional methods, our protocol is convenient and offers several advantages, such as shorter reaction time, higher yields, milder conditions and environmental friendliness. We have herein successfully demonstrated the synergistic outcome of multi-component reaction (MCR) and sonication to offer a facile route for the design of these derivatives.

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a b s t r a c tWe describe a one-pot four component synthesis of pyranopyroles from aryl aldehydes, ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of catalytic amounts of an organocatalyst imidazole in water as medium. A plausible mechanism for the formation of imidazole catalyzed pyranopyrazoles has been envisaged. This method is rapid, simple, provides products in good yield, and is eco-friendly. In addition, based on the optimized geometry, the frequency and intensity of the vibrational bands of 6-amino-4-(4 -methoxyphenyl)-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano[2,3-c]pyrazole were obtained by the density functional theory (DFT) calculations using 6-31G(d,p) basis set. The vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement.

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Nano-MgO a basic catalyst was prepared by solution combustion technique. It was characterized by powder XRD, SEM, BET and TEM analyses. It was used as a catalyst for the study of microwave-assisted Nformylation of various aromatic and alkyl amines with formic acid under solvent-free conditions. Nano-MgO showed excellent catalytic properties and the reactions went to completion, within 1-2 min to give products in high yield (90-98%). The catalyst is recoverable quantitatively and re-cycled with almost consistent activity. This new nano catalyst has the advantages of higher yield, lower cost, reduced environmental hazards, and the procedure is highly convenient.

a b s t r a c tA one-pot three-component condensation of an aldehyde, malononitrile, and resorcinol has been achieved by ultrasound method. The reaction has been catalyzed by glycine in aqueous medium. This protocol afforded corresponding 2-amino-4H-chromenes in shorter reaction times, high yields and simple work-up procedures with the green aspects by avoiding toxic reagents.

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