One-pot multi-component reactions especially under transition-metal-free catalysis served as an efficient, and environmentally friendly method for the construction of value-added compounds. Their importance in organic synthesis has drastically increased due to their operational simplicity, cost-effectiveness, step-and pot-economic nature. On the other hand, the molecular hybridization concept has recently emerged as a key fascinating area in medicinal and organic chemistry for the design of new drugs. Owing to the widespread occurrence in natural products, and pharmaceutical agents, the incorporation of another heterocycle either as substituents or as a fused material into 4-hydroxycoumarin moiety offers new opportunities for the broad application of the targeted coumarin-heterocycles into many branches of chemistry. Considering the importance of both the topics, here we have reviewed the developments achieved in the synthesis of diverse medicinally privileged oxygen, and nitrogen-containing heterocycles as well as spiro-heterocycles either linked or fused with coumarin moiety by using readily accessible 4-hydroxycoumarin as the starting material via one-pot multi-component reaction under transition-metalfree conditions.[a] B. Borah, K.

Here, we have developed a novel, simple, efficient, and green protocol for one-pot synthesis of pyrano[2,3-c]pyrazole using arylidene malononitrile and pyrazolone in Water Extract of Banana Peels (WEB) as a reaction medium at room temperature (r.t.). This is a green and general synthetic protocol without utilization of any toxic organic solvent, ligand, base that could be applicable for the wide substrate scope in good to excellent yields. This protocol has various advantages such as fast reactions, eco-friendly reaction conditions, easy isolation of the product without using column chromatography. The green chemistry matrices calculation like atom economy reaction, environmental factor, as well as process mass intensity indicates the eco-friendly nature of the protocol.

Pyrazolone is an important class of heterocyclic compounds with numerous applications in the fields of organic/material/pharmaceutical chemistry, food/textile industry and cosmetics. Because of these importances, the synthesis of biologically active complex molecules by employing pyrazolone has emerged. Dihydropyrano[2,3-c]pyrazoles and spiro-pyrano[2,3-c]pyrazoles are synthesized from pyrazolone and hold huge potential in the field of medicinal chemistry because of their wide-ranging biological activities. This review article will summarize the up to date advances on the application of pyrazolone in multicomponent reactions for the synthesis of dihydro-and spiro-pyrano[2,3-c]pyrazoles in aqueous medium.

Recent advances for the synthesis of pyrroles by employing organocatalysis are summarized in this review article.

The wide occurrence of pyrroles in natural products and pharmaceuticals calls for novel synthetic methodologies for the efficient synthesis of enantiopure pyrroles. Owing to their highly reactive nature and wide-ranging chemical landscape, enormous efforts have been dedicated not only to their synthesis but also to the development of reactions using them as a platform and their utilization in the stereocontrolled synthesis of diverse molecules. In sharp contrast to the extensive studies devoted toward indoles, the asymmetric functionalization of pyrroles was less explored. Never-theless, the attractiveness of pyrroles for their selective functionalization to access natural product analogy, and medicinally useful architectures have witnessed tremendous growth in the last few years. Their effectiveness under both metal-and organocatalytic conditions currently encompasses a vast majority of enantioselective transformations. This review article aims to present a comprehensive overview of the catalytic asymmetric CÀ H as well as NÀ H functionalization of pyrroles reported from 2010 to now.

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