microwave assisted synthesis of heterocycles | …
Microwave-assisted organic synthesis (MAOS) continues to be a popular theme within the realm of organic and medicinal chemistry community. Amongst the many five membered heterocycles, considerable interest has been focused on the pyrazole nucleus, which is known to possess a broad spectrum of biological properties such as hypoglycemic, cytotoxic, anti-malarial and antidepressant activities. Sulphonamides substituted on nitrogen of sulphonamido group such as sulphatihiazole, sulphapyridine, sulphadiazine, etc. show various biological activities. The present work describes the utility of microwave irradiation in the synthesis of some novel pyrazole derivatives which is somehow linked to sulphonamidophenyl group. All the synthesized compounds have been characterised by IR, NMR and Mass Spectral data. This book will surely help the researchers working in the area of Green Chemistry for the synthesis of heterocyclic compounds using microwave technology.
Microwave-Assisted Synthesis of Spirofused Heterocycles Using ..
Recent developments in the microwave-assisted synthesis of heterocycles are surveyed with the focus on diversity-oriented multi-component and multi-step one-pot procedures. Both solution- and solid-phase as well as polymer-supported methodologies for the preparation of libraries of heterocycles are reviewed. Advantages of microwave dielectric heating are highlighted by comparison with conventional thermal conditions.
Multicomponent reactions offer convenient procedures for the introduction of many points of structural diversity into heterocyclic compounds prepared in a straightforward manner in a single synthetic step. Combining these features with the extremely fast reaction kinetics of microwave-assisted organic synthesis provides new methods for the rapid and efficient synthesis of heterocyclic libraries suitable for biological evaluation and SAR studies. This review describes recent discoveries in microwave-assisted multicomponent reactions, primarily carried out using modern microwave synthesizers, for the preparation of both simple and fused heterocyclic targets. Advances in our understanding and the application of traditional multicomponent processes, including the Biginelli, Hantzsch and Ugi condensation reactions, for the synthesis of heterocycles are described, as well as a number of newly discovered multicomponent reactions for the preparation of nitrogen-, oxygen- and sulfur-containing, five- and six-membered, partially unsaturated or fully aromatic, heterocyclic rings. Methods for the construction of more complex fused heterocyclic motifs, and the benzo-derivatives of simple heterocycles, are described, with particular emphasis on new combinatorial methodology and the introduction of structural diversity. In many cases, microwave irradiation offers considerable improvements in chemical yield and constitutes a very simple and extremely rapid method to access a diverse range of heterocyclic motifs.