Microwave-assisted Synthesis of Heterocyclic Compounds on Solid Supports

Microwave-assisted Synthesis of Heterocyclic Compounds on Solid Supports 

HeterocycHc chemistry has been a major beneficiary of MW-expedited solvent-free chemistry using mineral-supported reagents developed since the mid-1990s, and numerous reports have appeared that employ this technique to assemble a variety of heterocycles [133]. 

The conventional preparations ofthiazoles and 2-aroylbenzo[b]furans require the use of lachrymatory a-haloketones and thioureas (or thioamides). In a process that eliminates this problem, Varma et al. have synthesized various heterocyles via sim- 

A similar MW strategy has been used to synthesize a set of pyrimidinones (65-95%) via the Biginelli condensation reaction in a household MW oven and has been successfully applied to combinatorial synthesis [139]. More recent examples describe a convenient synthesis of highly substituted pyrroles (60-72%) on silica gel using readily available a, 3-unsaturated carbonyl compounds, amines, and ni-troalkanes [140], and the use of neat reactants under solvent-free conditions to generate Biginelli and Hantzsch reaction products with enhanced yields and shortened reaction times [141]. 

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