A novel three-component reaction for the diastereoselective synthesis of 2H-pyrimido[2,1-a]isoquinolines via 1,4-dipolar cycloaddition.

[reaction: see text] The 1,4-dipole derived from isoquinoline and DMAD has been shown to react readily with N-tosylimines resulting in the diastereoselective synthesis of 2H-pyrimido[2,1-a]isoquinoline derivatives.