Study On Green Oriented Functionalization Of Imidazoheterocycles And Formation Of Pyrrole Ring

Imidazoheterocycles and pyrroles are important molecular skeleton,which are found in numerous natural products and pharmaceuticals.Due to the unique biological and physiological activities,they have been widely used in biomedicine and materials science.Therefore,the synthesis and modification of imidazoheterocycles and pyrroles have been a research hotspot in the field of organic chemistry.It is highly essential to develop highly efficient,eco-friendly,practical and applicable methods for the synthesis of imidazoheterocycles and pyrroles,which meets the guiding principles of green chemistry.In this paper,green oriented synthesis of imidazoheterocycles and pyrroles were investigated.The contents include five parts:?1?The progress for the synthesis of pyrroloquinolines was reviewed.C–H functionalization of imidazoheterocycles including C–H arylation,alkenylation,carbonylation and sulfenylation were summarized.?2?NH₄PF₆-promoted cyclodehydration of ?-amino carbonyl Compounds: efficient synthesis of pyrroloquinolines and indoles derivatives has been studied.This new strategy provided a convenient and efficient route for the preparation of pyrroloquinolines and indoles without using metal reagents and the sole by-product was water.Morever,the simple post-treatment and easy recovery of solvent helps to protect the environment.?3?Direct regioselective C–H sulfenylation of imidazoheterocycleswith disulfides has been studied.The reaction proceeded in ethanol at 25 oC under iodine-hydrogen peroxide system.This green strategy tolerates a wide range of functional groups to afford diverse sulfenylated imidazoheterocycles under mild conditions.?4?Direct regioselective C–H trifluoromethylation of imidazoheterocycles with Langlois` reagent has been studied.The mixture of [Bmim]BF4 and H₂ O has been found to be an effective reaction medium for the trifluoromethylation.This green strategy tolerates a wide range of functional groups to afford diverse trifluoromethylated imidazoheterocycles.Several phenyl-substituted1H-imidazoles were also suitable for the trifluoromethylation under the standard conditions.?5?Regioselective C–H heteroarylation of imidazoheterocycles with2-aminobenzothiazoles has been studied.A metal-free oxidative deamination cross-coupling of imidazoheterocycles with2-aminobenzothiazoles in the presence of tert-butyl nitrite was carried out for the first time.This finding offers a simple and practicable method for the synthesis of a variety of highly conjugated heterocycles with the release of nitrogen and water as benign byproducts.