annulated benzo[a]quinolizine-4-thiones 3 has been developed. The methodology involves ring annulation of 3,4-dihydro-6,7-dimethoxy-1-methylisoquinoline 1 with a variety of readily accessible acyclic and cyclic beta-oxodithioesters 2 in the presence of triethylamine in refluxing benzene. These benzo[a]quinolizine-4-thiones can be readily converted to the corresponding benzo[a]quinolizine-4-ones 5 via dethiomethylative