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In the present letter, an efficient, clean and one-pot synthesis of 2-substituted benzimidazole and 1,2-disubstituted benzimidazole derivatives has been explored by reacting o -phenylenediamine with aromatic aldehydes using bismuth nitrate as a catalyst in ethanol at ambient temperature. This methodology avails with faster reactions, excellent yield, mild reaction conditions, use of inexpensive and non-toxic catalyst compared to literature reported hitherto.

The title compounds such as (III) are highly efficiently obtained starting from primary aliphatic amines in aqueous media via a nonisothiocyanate route without the use of any catalyst and without any side product formation.

12 Title compounds of type (III), (V), or (VII) are prepared by a ring transformation reaction via a two-carbon insertion from 2-acetylpyridine (II).

We report a greener, economical, highly convenient and regioselective synthesis of (2E)-2-[2,3,6-arylpyrimidin-4(3H)-ylidene)acetonitriles derivatives 3. This is achieved by a strategy involving ring transformation reaction of 4-(methylthio)-2-oxo-6-aryl-2H-pyran-3-carbonitrile 1 with N-arylbenzamidine or N-arylpicolinamidine 2 in the presence of KOH/DMF catalyst at room temperature. This approach provides a one-pot approach for the synthesis of symmetrical, unsymmetrical and heteroaryl pyrimidin-4(3H)-ylidene)acetonitriles derivatives 3. Figure options Download full-size image Download as PowerPoint slide

From acyl Meldrum′s acid (I), intermediary formed β-keto esters are used for the microwave assisted one-pot synthesis of diverse heterocycles.

Novel 2-biaryl-benzimidazoles (V) and (VII) are prepared via microwave-assisted Suzuki-Miyaura coupling followed by alkylation and acylation, respectively.

The title compounds (V) and (VIII) display good antibacterial activity against S.aureus but they are less active against S.

Microwave‐assisted, solvent‐free alkylation and acylation of 2‐mercaptobenzothiazole has been attempted using silica gel, alumina, and a new solid support, fly ash. Fly ash, a waste generated at thermal power stations, could be used as solid support just as efficiently as commercial supports. The additional features of methodology include a much faster reaction, easy workup, higher yields, higher purity of the products, and an ecofriendly approach.

Microwave mediated rapid and efficient synthesis of aryl methyl ketones and β-keto esters from acyl Meldrum's acid by hydrolysis and alcoholysis, respectively, has been reported.

Meldrum's acid (1) on bisacylation with succinyl chloride afforded a neutral diketo product (2); however, the dimer enolic products (3) with acidic nature resulted in glutaryl and adipyl dichlorides. Monoacylation of (1) with acetyl chloride gave acidic 5‐acetyl Meldrum's acid (4) in enol form. Presented at the National Symposium on Newer Concepts in Organic Synthesis, 1998, Aurangabad, India, [Abstract: 1.29]. This paper is dedicated to Prof. M. M. Salunkhe, Vice-Chancellor, Shivaji University, Kolhapur–416 004 (Former Director, Institute of Science, Mumbai – 400 032) India.