X-ray mapping in heterocyclic design: VIII. Synthesis and X-ray diffraction study of dimethyl 3-(p-chlorobenzoyl)-5-chloroindolizine-1,2-dicarboxylate and the product of its cyclization 1,2-bis(carbomethoxy)-6-chloro-3H-isoquinolino[1,2,3-d,c]indolizine-3-one

Dimethyl 3-(p-chlorobenzoyl)-5-chloroindolizine-1,2-dicarboxylate, C₁₉H₁₃Cl₂NO₅, (2) and the product of its cyclization 1,2-bis(carbomethoxy)-6-chloro-3H-isoquinolino1,2,3-d,c]indolizine-3-one, C₁₉H₁₂ClNO₅, (3) are synthesized, and their molecular and crystal structures are determined by the single-crystal X-ray diffraction technique. Crystals 2 are monoclinic, a = 9.627(3) Å, b = 6.646(2) Å, c = 28.500(9) Å, β = 98.72(2)°, Z = 4, and space group P2₁/c. Crystals 3 are monoclinic, a = 7.048(4) Å, b = 10.582(4) Å, c = 21.760(7) Å, β = 97.23(4)°, Z = 4, and space group P2₁/c. The structures are solved by the direct method and refined in the anisotropic approximation by the full-matrix least-squares procedure to R = 0.0504 and 0.0510 for 2 and 3, respectively. In both structures, the intramolecular and intermolecular contacts involving the C, H, and O atoms are observed.