ABSTRACT
A condition-based skeletal divergent synthesis was explored to achieve skeletal diversity in two component condensation reaction. Cyanomethyl benzimidazole was reacted with α-bromoketone under thermal conditions to furnish 2-aminofuranyl-benzimidazoles, while the same reaction afforded 3-cyano-benzopyrrolo-imidazoles under microwave irradiation. Two nonequivalent nucleophilic centers on benzimidazole moiety were manipulated elegantly by different reaction conditions to achieve the skeletal diversity.
Subject(s)
Benzimidazoles/chemical synthesis , Furans/chemical synthesis , Imidazoles/chemical synthesis , Nitriles/chemical synthesis , Pyrroles/chemical synthesis , Magnetic Resonance Imaging , Mass Spectrometry , Microwaves , Molecular Structure , StereoisomerismABSTRACT
A two-step, three-component coupling reaction on ionic liquid supported 2-cyanomethylbenzimidazoles, methyl 2-formylbenzoate, and isocyanides under microwave activation is explored. Knoevenagel condensation of 2-cyanomethylbenzimidazole with methyl-2-formylbenzoate in the presence of piperidine catalyst is followed by [4+1] cycloaddition with an isocyanide in the next step. Consequent intramolecular δ-lactam formation allows rapid construction of novel aza-pentacycles, benzimidazo[1',2':1,5]pyrrolo[2,3-c]isoquinolines.
