Pd-Catalyzed annulation of imidazo[1,2-a]pyridines with coumarins and indoles: Synthesis of benzofuran and indole fused heterocycles

Palladium-catalyzed annulation of imidazo[1,2-a]pyridines with coumarins provided the benzofuran fused transannulated products in good to excellent yields via decarbonylative approach. While imidazo[1,2-a]pyridines with N-methyl indoles in the presence of palladium...

Green Multi-Component Synthesis of Fused heterocyclic derivatives: An atom economic ecofriendly approach for complex molecules

Background: The construction of fused heterocyclic compounds is always fascinating on the strength of their applications as novel pharmaceuticals. Multi-component reactions (MCRs) are atom economical, beneficial, straightforward and ecofriendly approach for synthesis of complex heterocycles in a single step with higher selectivity. Methods: The review mainly focused on the synthesis of fused heterocycles such as pyrimidine - chromene, Pyrrolo - pyrazine, Pyrazolo - pyrimidine, pyran - imidazole and pyrazole- imidazole - pyrimidine, pyran - pyridmidone, pyrrolo - chromene, pyridine-pyrimidinone, fused indole derivatives, furano - pyran along with some simple MCRs discussed, which published in in the period of 2019 and 2020. A table of summary about 50 heterocycles with product, catalysts and cited literature for are given at end. Conclusions: From this review we understand that MCRs can deliver an effortless access to molecular targets of our interest with wide choice of reactants and their combinations. Thus, the creativity and choice of reactants are pushing the development in MCRs towards more atom economical and eco-friendly approach Objective: Understanding recent trends in the development of MCRs is a requisite for anyone, who wish to synthesise simple and fused heterocycles. By keeping this as primary objective, the present review provides an overview of latest developments in fused heterocyclic synthesis via green multicomponent reactions in the period of 2019 and 2020.

Oxidative [3+2]-annulation of nitroalkenes and azolium ylides in the presence of Cu(II): efficient synthesis of [5,5]-annulated N-fused heterocycles

A facile synthesis of [5,5]-annulated N-fused heterocycles – pyrrolo[2,1-b]thiazoles and pyrrolo[1,2-b]indazoles via Cu(II)-mediated oxidative [3+2]-annulation between nitroalkenes and azolium ylides was developed. The reaction proceeds in mild conditions with copper (II) trifluoroacetate/2,6-lutidine system as a promoter. The method is applicable to a broad range of nitroalkenes and azolium salts, providing target N-fused heterocycles in moderate to good yields. In the case of α-fluoronitroalkenes unique fluorinated derivatives were accessed via this methodology.