Ultrasonicated synthesis of novel quinoline-lipoyl peptides through Ugi-four component condensation by using Ca/BN catalyst

Abstract

ABSTRACTAn efficient one pot Ugi four-component condensation reaction was implemented for the development of new quinoline-peptides. Lipoic acid, 2-methoxy-3-formyl quinoline carboxaldehyde derivatives, aniline derivatives and cyclohexyl isocyanide were employed to synthesize quinoline-lipoyl peptides. This one-pot condensation reaction was successfully carried out by using a new green heterogeneous catalyst: calcium loaded boron nitride (Ca/BN), under ultrasonication at room temperature. The Ca/BN can be easily synthesized by stirring at room temperature. It can also be separated by simple filtration and recycled more than five times. The catalyst was characterized by XRD, SEM with EDX, Raman spectroscopy, BET, DSC-TGA and FTIR. A novel series of N-(2-(cyclohexylamino)-1-(2-methoxyquinolin-3-yl)-2-oxoethyl)-5-((R)-1,2-dithiolan-3-yl)-N-phenylpentanamide (Ugi-adduct) were easily synthesized. All the compounds were characterized by FTIR, 1H-NMR, 13C-NMR and elemental analysis. A total of 14 peptides with good yield is reported herein.