An efficient approach one-pot three-component synthesis of pyrimido[۲,۱-b][۱,۳]oxazine derivatives via reaction of dialkyl acetylenedicarboxylates with isocyanide derivatives in the presence of ۶-methyl-۵-nitrouracil

The reaction of isocyanide derivatives with dialkyl acetylenedicarboxylates in the presence of ۶-methyl-۵-nitrouracil to proceeded smoothly at room temperature and under mild conditions to afford synthesis of dialkyl-۲-(alkylamino)-۶- methyl-۷-nitro-۸-oxo-۴H,۸H-pyrimido[۲,۱-b][۱,۳]oxazine-۳,۴-dicarboxylate derivatives in excellent yields. All products were established by IR, ۱HNMR, ۱۳CNMR, Mass spectroscopy and elemental analysis