Preparation of a Useful Synthetic Precursor, 2-Substituted 4(3H)-Quinazolinone: Directed Lithiation and N3-Deprotection of 3-t-Butoxycarbonyl-4(3H)-quinazolinone

Directed lithiation of 3-t-butoxycarbonyl-4(3H)-quinazolinone using LDA was accomplished to afford 2-substituted 3-t-butoxycarbonyl-4(3H)quinazolinones.The t-butoxycarbonyl group of these products was easily deprotected to give key intermediates for the synthesis of quinazoline derivatives, 2-substituted 4(3H)-quinazolinones, in good yield.