Saturated heterocycles. 57. Synthesis of 4-substituted-9,10-dialkoxy-1,6,7,11b-tetrahydro-2H-pyrimido[6,1-a]isoquinolin-2-ones

A large number of 4-substituted-9,10-dialkoxy-1,6,7,11b-tetrahydropyrimido6,1-a]isoquinolin-2-ones were prepared by the reaction of 1-(ethoxycarbonylmethyl)-6,7-dialkoxy-1,2,3,4-tetrahydroisoquinolines with iminoethers. Reaction of the corresponding isoquinoline-1-acetic acid derivatives with iminoethers led to the formation of N-acyl-1,2,3,4-tetrahydroisoquinolin-1-acetamides. In the hydrolysis of the prepared 4-substituted-pyrimido6,1-a]isoquinolin-2-ones, the corresponding N-acyl-1,2,3,4-tetrahydroisoquinolin-1-acetamides were obtained. While reduction of the 4-phenyl derivative resulted in the corresponding 1,3,4,6,7,11b-hexahydropyrimidinone. The steric structures of the tetrahydro- and hexahydropyrimido6,1-a]isoquinolines were determined by nmr spectroscopy.