Efficient Synthesis of 2-Aminoquinazoline Derivatives via Acid-Mediated [4+2] Annulation of N-Benzyl Cyanamides

The synthesis of 2-aminoquinazoline derivatives is achieved by using hydrochloric acid as a mediator in the [4+2] annulation reaction between N-benzyl cyanamides and 2-amino aryl ketones. In addition, 2-amino-4-iminoquinazolines are synthesized by the reaction of 2-aminobenzonitriles, instead of 2-amino aryl ketones, with N-benzyl cyanamides. A wide range of substrates can be used and high yields are obtained, demonstrating the practicality of this method for the synthesis of 2-aminoquinazoline derivatives.