Concise Synthesis of Highly Substituted Benzo[a]quinolizines by a Multicomponent Reaction/Allylation/Heck Reaction Sequence

The combination of the recently developed multicomponent construction of highly substituted 3,4-dihydropyridones with subsequent allylation and intramolecular Heck-type cyclization allows the straightforward construction of benzo[a]quinolizines, a class of polycyclic compounds that - despite their interesting pharmacological and photochemical properties - have little precedent in the literature. After optimization of the individual steps, we used this reliable three-step sequence to generate a small library of diversely substituted benzo[a]quinolizines and various heterocyclic analogs.