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A newly discovered easy and simple four-component domino reaction via combination of four common reactants and [Cs.sub.2]C[O.sub.3] in ethylene glycol under microwave heating is described. The resulting tricyclo[6.2.2.01,6]dodecane derivatives could find important application for organic and medicinal research.

Concise and efficient six-component and four-component domino methods to anti-1,2-diarylethylbenzamides and highly substituted 2-(2'-azaaryl)imidazoles developed under solvent-free and microwave-irradiation conditions are presented. The reactions involving new mechanism of microwave enabled umpulong showed a broad scope of substrates in which a wide range of common commercial aromatic aldehydes and heteroaryl nitriles could be used.

New multicomponent domino reactions of arylglyoxals with pyrazol-5-amines have been established, providing selective access to unprecedented pyrazolo-fused 1,7-naphthyridines, 1,3-diazocanes, and pyrroles (up to 52 examples). The unreported dipyrazolo-fused 1,7-naphthyridines were regioselectively synthesized through a special double [3 + 2 + 1] heteroannulation accompanied by direct C-C formation between two electrophilic sites of arylglyoxals. The unusual [3 + 3 + 1 + 1] cyclization resulted in 20 examples of novel dipyrazolo-fused 1,3-diazocanes, whereas pyrrolo[2,3-c]pyrazoles were obtained in good yields by varying arylglyoxals 1 and pyrazol-5-amines 2 in the ratio 1:2. Mechanisms of formation of these three new types of heterocycles are also proposed. [ABSTRACT FROM AUTHOR]

New oxidative dehydrogenative couplings of pyrazol-5-amines for the selective synthesis of azopyrrole derivatives have been described. The former reaction simultaneously installs C-I and N-N bonds through iodination and oxidation, whereas the latter involved a copper-catalyzed oxidative coupling process. The resulting iodo-substituted azopyrroles were employed by treatment with various terminal alkynes through Sonogashira cross-coupling leading to new azo compounds. [ABSTRACT FROM AUTHOR]

A K2S2O8-mediated direct cross-coupling of quinoxalines (or benzothiazoles) with methanol leading to 2-quinoxalinyl (or 2-benzothiazolyl) carbaldehyde dimethyl acetals has been achieved. 2-Quinoxalinyl carbaldehyde dimethyl acetals were readily converted into 2-quinoxalinyl carbaldehydes in good to excellent yields under addle conditions. Preliminary mechanistic studies suggest that the reaction proceeds via multifold bond cleavage and formation between methanol and N-heterocycles involving a dioxygen-participated radical process. This method allows for the synthesis of a variety of 2-quinoxalinyl (or 2-benzothiazolyl) carbaldehyde dimethyl acetals directly via cross-coupling of simple N-heterocyclic C-H bond and methanol under aldehyde-, add-, and transition-metal-free conditions. [ABSTRACT FROM AUTHOR]

New three-component domino reaction providing divergent approaches to multifunctionalized fused pyrroles with different substituted patterns have been established (40 examples). The direct C(sp³)-N bond formation was achieved through intermolecular allylic amination in a one-pot operation, and N-arylation of amines was realized by varying N-amino acid enaminones. The reaction is easy to perform simply by mixing three common reactants in acetic acid under microwave heating. The reaction proceeds at fast rates and can be finished within 30 min, which makes workup convenient to give good chemical yields. [ABSTRACT FROM AUTHOR]

A novel four-component domino reaction has been discovered. The reaction is easy to perform simply by mixing four common reactants and Cs2CO3 in ethylene glycol under microwave heating. The reaction proceeds at fast rates and can be finished within 15-24 mm, which makes workup convenient. Four stereogenic centers with one quaternary carbon-amino function have been controlled completely. The stereochemistry has been unequivocally determined by X-ray structural analysis. The resulting tricyclo[6.2.2.01,6]dodecane derivatives are of importance for organic and medicinal research. [ABSTRACT FROM AUTHOR]