A facile and rapid one-step synthesis of 8-substituted xanthine derivatives via tandem ring closure at room temperature

N-Bromo succinimide (NBS) was found to be an efficient and regioselective reagent in combination with AIBN for an unprecedented, facile and rapid one-step synthesis of 8-substituted xanthine derivatives at room temperature. The inexpensive, nontoxic and readily available NBS efficiently promoted the condensation of several aryl/cycloaryl/heteroaryl aldehydes with 5,6-diamino-1,3-dimethyluracils in presence of catalytic amount of AIBN in a single step via radical chain reaction. The notable advantages of this protocol were short reaction time, milder reaction conditions, simple work-up procedure, no requirement for chromatographic separation, use of non-hazardous reagent/solvent and applicable to a variety of substrates.