Condensation of 2-acetylnaphthalene with benzaldehydes under microwave irradiation affords chalcones which undergo facile and clean cyclizations with hydrazines RNHNH2 (R= H, Ph, Ac) to afford 3,5-arylated 2-pyrazolines in quantitative yields, also under microwave irradiation and in the presence of dry AcOH as cyclizing agent. The results obtained indicate that, unlike classical heating, microwave irradiation results in higher yields, shorter reaction times (2-12 min.) and cleaner reactions.

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A novel procedure for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes through one-pot condensation of naphthalen-2-ol with arenecarbaldehydes in the presence of N-bromosuccinimide (NBS) as catalyst under solvent-free conditions is described.

The stepwise and concerted ionic Diels-Alder reactions between phenyl(pyridin-2-ylmethylene)oxonium and styrene derivatives were explored theoretically. The results support the use of a computational method via persistent intermediates. The DFT method was essential to reproduce a reasonable potential energy surface for these challenging systems.

Protection O 03451,3-Dibromo-5,5-dimethylhydantoin as Catalyst for the Conversion of Aldehydes to Their 1,1-Diacetates (Acetylals) under Solvent-Free and Neutral Conditions.-Aliphatic and aromatic aldehydes (I) are converted to acetylals (III) in very high yields in neutral reaction media avoiding strong acids. The conversion proceeds selectivity in the presence of a ketone without affecting the ketone functionality. The neutrality of the reaction media, high selectivity, easy work-up, high yields, mild reaction conditions, and solvent-free conditions are the features of this process, thus making it suitable for the direct conversion of aldehydes into acetylals. -(AZARIFAR*, D.; GHASEMNEJAD, H.; RAMZANIAN-LEHMALI, F.; Mendeleev Commun. 2005, 5, 209-210; Dep. Chem., Coll. Sci., Univ. Bu-Ali Sina, Hamadan 65174, Iran; Eng.) -H. Hoennerscheid 06-063