Multi‐Component Reaction of 6‐Aminouracils, Aldehydes and Secondary Amines: Conversion of the Products into Pyrimido[4,5‐d]pyrimidines through C‐H Amination/Cyclization

Abstract Reaction of 6‐aminouracils with aldehydes and secondary amines catalyzed by acetic acid is reported here. This is in fact a domino aza‐Michael reaction. 6‐Aminouracil reacts first with aldehyde and then amine attacks the newly formed C=C bond, which is established from the mass spectral analysis of the reaction mixture. The products of the reaction are cyclized to pyrimido[4,5‐ d ]‐pyrimidines via intramolecular α‐C−H functionalization of tertiary amine promoted by I 2 ‐TBHP at room temperature in ethanol solvent. I 2 (10 mol %) and TBHP (1.5 eq.) are used for the cyclization reactions. Based on few controlled experiments a tentative radical mechanism is proposed for the cyclization step.