Synthesis of 2,4‐Diaminoquinazolines and 2‐Amino‐4‐iminoquinazolines via Substrate‐Controlled Annulation of 2‐Aminobenzonitriles and Carbodiimides

Abstract An efficient methodology for the synthesis of 2,4‐diaminoquinazolines and 2‐amino‐4‐iminoquinazolines from 2‐aminobenzonitriles and carbodiimides is described. This SnCl 4 mediated reaction exhibits substrate driven switchable selectivity in product formation based on the substituents of the carbodiimides used. Aryl and primary alkyl‐substituted carbodiimides predominantly give 2‐amino‐4‐iminoquinazolines, while secondary or tertiary alkyl and benzyl‐substituted carbodiimides yield 2,4‐diaminoquinazolines. Products were also transformed into its oxo‐analogues 2‐aminoquinazolin‐4(3 H )‐ones through hydrolysis and into highly fused pentacyclic derivatives through Ru(II)‐catalyzed C─H/N─H annulation reaction with diphenylacetylene.