One-pot four-component synthesis of pyrimido[۲,۱-a]isoquinoline-۳,۴- dicarboxylate derivatives via the reaction of phthalaldehyde, ammonium acetate and dialkyl acetylenedicarboxylates in the presence of phenyl isocyanate derivatives

The reaction of phthalaldehyde, ammonium acetate and dialkyl acetylenedicarboxylates in the presence of phenyl isocyanate derivatives to proceeded at room temperature and under mild conditions to afford synthesis of dialkyl-۱-(۴-(alkyl)phenyl)-۲-oxo- ۱,۱۱b-dihydro-۲H-pyrimido[۲,۱-a]isoquinoline-۳,۴-dicarboxylate derivatives in excellent yields. All products were established by IR, ۱H, ۱۳CNMR, Mass spectroscopy and elemental analysis.