Double anion capture reactions of anthranilic esters with oxaldiimidoyl dichlorides - Efficient synthesis of 2,2'-biquinazoline-4,4'(3H,3'H)-diones

The reaction of anthranilic acids with oxaldiimidoyl dichlorides offers a n ew and convenient synthesis of quinazolin-4-ones. Condensation of anthranil ic esters with diimidoyl dichlorides affords 2,2'-biquinazoline-4,4'(3H,3'H )-diones, which constitute a new class of dimeric heterocyclic compounds. I n contrast. condensation of the dianion of N-methyl ortho-tolylamide with d i(imidoyl) dichlorides affords seven-rather than six-membered ring products . Starting with 2-aminopyridine, 2,3-diimino-2,3-dihydroimidazo[l,2-a]pyrid ines could be efficiently prepared.