Metal-Free Multicomponent Syntheses of Pyridines

Because of the significant role in biological processes in living cells and the diverse types of physiological activities, heterocyclic compounds are in focus of intense investigations by academic and applied-oriented chemists. Considerably, a scientific renaissance of heterocycles during the last decades is closely related to the development of multicomponent approaches to their synthesis. Multicomponent methodology fundamentally different from two-component or sequential processes together with other innovative synthetic methods like microwave- and ultrasonic- assisted reactions offer some new possibilities in constructing heterocyclic systems with high level of molecular diversity and complexity. An overview of known multicomponent heterocyclizations using aminoazoles as a key reagent and their rich synthetic potential for obtaining five-, six-, and seven-membered heterocycles is presented. A special attention is paid to the tuning of chemo- and regio- and positional selectivity of some reactions as well as to the application of nonclassical activation methods based on microwave and ultrasonic irradiation.

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Aminoazoles as Key Reagents in Multicomponent Heterocyclizations

Highly Regioselective One-Pot, Three-Component Synthesis of 1-Aryl-3,4-Substituted/Annulated-5-(Cycloamino)/(Alkylamino)pyrazoles from β-Oxodithioesters

Synthesis of novel benzo[h]-1,6-naphthyridines was successfully achieved by cyclocondensation of ethyl 4-aminoquinoline-3-carboxylates with malononitrile. The pyrazolo[4,3-c]quinolines were synthesized by nucleophilic substitution and subsequent addition reaction of ethyl 4-chloroquinoline-3-carboxylates with different hydrazines. All new compounds were characterized by spectral and analytical methods.

B. Toche Raghunath

Papers

Synthesis of Pyrazolo[3,4-b]pyridines Using Ammonium Acetate as Green Reagent in Multi-component Reactions