A New Synthesis of Pyrazino[2,3-c]isoquinolines

Abstract

A convenient synthesis of 1-(p-chlorophenoxy )isoquinoline-3,4-diame is described. Condensation with ethyl pyruvate gave entry to the tricyclic title system, and some further nucleophilic displacement reactions of substituent groups are described. The direction of ring closure in the tricycle formation was proved by determining the crystal structure of one of the derivatives; rhombohedral crystals of (3b) belong to the space group R3 with a 21.822(5)Ǻ, α 116.81(2)° and Z 12. Full-matrix refinement using 3093 reflections converged at R 0.085.