Multi-component reaction pyridine synthesis

Zhu SL, Ji SJ, Su XM et al (2008) Facile and efficient synthesis of a new class of bis(3 -indolyl) pyridine derivatives via one-pot multi-component reactions. Tetrahedron Lett 49 1777-1781... 

Tu SJ, Zhang XH, Han ZG et al (2009) Synthesis of isoxazolo[5, 4-b]pyridines by microwave-assisted multi-component reactions in water. J Comb Chem 11 428 32... 

Feng S, Yan Z, Shu-Jiang T et al (2008) A green approach to the synthesis of biologically important indeno[2, l-e]pyrazolo[5, 4-b]pyridines via microwave-assisted multi-component reactions in water. Chin J Chem 26 1262-1266... 

Heterocyclic chemistry has been a major beneficiary of MW-expedited solvent-lfee chemistry utilizing mineral supported reagents. It has been exploited for parallel synthesis, a strategy that is adaptable for multicomponent reactions, such as Ugi " and Biginelli reactions " , for rapid assembly of a library of compoimds. A representative multi-component condensation reaction to create a small-molecule library of imidazo[l,2-a]pyridines, imidazo[l,2-a] pyrazines, and imidazo[l,2-a]pyrimidines is depicted in Scheme 3. 

Bora and co-workers44 have developed a microwave-assisted three-component synthesis of indolizines. The reaction involves a 1,3-dipolar cycloaddition reaction between the in situ generated dipole (from the bromoacetophenone and pyridine) and acetylene, Scheme 5.26. The developed method provides fast access to cycloadducts, which otherwise are accessible only through multi-step synthesis. 

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