ABSTRACT
Heterogeneous catalysts have gained much importance in recent years due to economic and environmental considerations. These catalysts are advantageous over homogeneous catalysts as they can be easily recovered from the reaction mixture by simple ltration and can be reused after activation, thereby making the process
6.1 Introduction .................................................................................................. 163 6.2 Synthesis of Bioactive Heterocycles ............................................................. 164
6.2.1 Dihydropyrimidine Synthesis ........................................................... 164 6.2.2 Benzimidazole Synthesis .................................................................. 168 6.2.3 Imidazole Synthesis .......................................................................... 170 6.2.4 Quinazolinone Synthesis .................................................................. 172 6.2.5 Quinoline Synthesis .......................................................................... 173 6.2.6 Oxadiazole Synthesis ........................................................................ 174 6.2.7 Benzothiazole Synthesis ................................................................... 175 6.2.8 Quinoxaline Synthesis ...................................................................... 176 6.2.9 Pyrrole Synthesis .............................................................................. 176 6.2.10 Pyrazole Synthesis ............................................................................ 177 6.2.11 Pyrazine, Thiazine, Piperidine, Indole, Phthalazine, Triazole,
Dihydroquinolinone, Tetrazoline, and Acridine Synthesis .............. 178 6.3 Conclusion .................................................................................................... 183 Acknowledgments .................................................................................................. 184 References .............................................................................................................. 184
economically viable. There has been a tremendous upsurge of interest in various chemical transformations promoted by catalysts under heterogeneous conditions (Smith and Notheisz, 2000; Santen and Neurock, 2006). Generally, reactions with these catalysts are clean and selective and give high yields of products. In these days of growing environmental concerns, heterogeneous catalysts have attracted much attention as catalysts for organic synthesis.
