Microwave-assisted multicomponent reaction of aryl amidines: regiospecific synthesis of new polysubstituted thiopyrano-, and pyrano[4,3-d]pyrimidines

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

Microwave-assisted (MWA) multicomponent reactions (MCRs) have successfully emerged as one of the useful tools in the synthesis of biologically relevant heterocycles. These reactions are strategically employed for the generation of a variety of heterocycles along with multiple point diversifications. Over the last few decades classical MCRs such as Ugi, Biginelli, etc. have witnessed enhanced yield and efficiency with microwave assistance. The highlights of MWA-MCRs are high yields, reduced reaction time, selectivity, atom economy and simpler purification techniques, such an approach can accelerate the drug discovery process. The present review focuses on the recent advances in MWA-MCRs and their mechanistic insights over the past decade and shed light on its advantage over the conventional approach.

A Green Approach for Organic Transformations Using Microwave Reactor

Microwave-assisted organic transformation (MAOR) is presently gaining wide popularity in the field of organic synthesis. The conventional heating technique is gradually being removed from the laboratory and a novel microwave heating technique established to be used in both academia and industry. As compared to the classical organic methodology, the green technology tools have several advantages like dramatically reduced reaction times, improved yields, site selectivity, and the increased product purities with simplification of work-up procedures. In the current study, we have briefly described the overview of recent developments and applications of microwave irradiation in organic transformation with schematic compiling of the organic reactions, bioactive heterocyclic compounds, and so on. This review also presents a critical analysis of the various advantages of microwave irradiation in organic synthesis/transformation compared to the classical or conventional heating. So, we believe that our current study of the green microwave heating technique will be highly beneficial for the researchers from both academia and industry in their near future.

Microwave-Assisted Synthesis of Bioactive Six-Membered Heterocycles and Their Fused Analogues

This review describes the formation of six-membered heterocyclic compounds and their fused analogues under microwave activation using modern organic transformations including cyclocondensation, cycloaddition, multicomponents and other modular reactions. The review is divided according to the main heterocycle types in order of increasing complexity, starting with heterocyclic systems containing one, two and three heteroatoms and their fused analogues. Recent microwave applications are reviewed, with special focus on the chemistry of bioactive compounds. Selected examples from the 2006 to 2015 literature are discussed.

An efficient, one-pot three-component synthesis of 4H-thiazolo[3,2-a][1,3,5]triazin-6-one derivatives

A simple and efficient protocol was established to synthesize thiazolo[3,2-a][1,3,5]triazin-6-ones via three-component one-pot condensation reaction of readily available thioglycolic acid or ethyl thioglycolate, aldehydes or ketones and dicyandiamide in the presence of ammonium acetate. All of the newly synthesized compounds were characterized by spectroscopic analyses.

Ultrasound-promoted one-pot five-components synthesis of biologically active novel bis((6-alkyl or phenyl-2-phenylpyrimidine-4-yl) oxy) alkane or methyl benzene derivatives

We have described a synthesis of novel five-component reaction (5-CR) of bis((6-alkyl or phenyl-2-phenylpyrimidine-4-yl) oxy) alkane or methyl benzene derivatives under ultrasound irradiation. A useful ultrasound effect was observed and title products were obtained with high yields after 25-40 min sonication. Structural confirmation and characterization of the products based on the analytical, chemical, and spectral analysis. The results show obviously, that to reach a high efficiency of ultrasonic systems in synthetic chemical processes. Our procedure compared to the conventional heating method has the benefit of higher reaction yields and shorter reaction times. The in vitro antibacterial tests show that some of the target compounds have promising activities. Structure-activity relationships (SAR) were established for the substitutions on the pyrimidine rings and related length of linear chain linker.