Photocatalytic cyclization of 3-(2-isocyanophenyl)quinazolin-4(3H)-ones for the construction of quinoxalino[2,1-b]quinazolinones

3-(2-Isocyanophenyl)quinazolin-4(3 H )-ones were designed and synthesized as new building units for the construction of novel quinoxalino[2,1- b ]quinazolinones under mild, photocatalytic and metal-free conditions.