A Diversity-Oriented Synthesis Approach to Functionalized Azaheterocycles using Cyclic Alpha-Halo Eneformamides

Functionalized piperidines, azepanes, azamacrocycles, morpholines, and thiomorpholines are common structural motifs found in a wide range of pharmaceuticals such as carmegliptine, levofloxacin, thioridazine, claviciptic acid, and azithomycin. As a result, there is a strong desire to construct highly functionalized nitrogen-bearing ring scaffolds in order to construct a wide range of drug possibilities. There are several non-modular and step-uneconomical synthetic methods used in the construction of these aforementioned motifs such as ring closing metathesis, ring expansions, and intramolecular reductive amination. In this research, we present a step-economical, cost-effective, scalable, and diversity-oriented synthesis approach to highly functionalized N-heterocycles through the intermediacy of α-halo enamines/enamides. The synthetic utility of the method is exemplified through the construction of quaternary cyclic propargylic and homoallylic amines, polycyclic lactams, as well as chiral dihydro 1,4-oxazines and thiazines. Given the generality of the approach, we are confident that the synthesis and medicinal chemistry communities will undoubtedly embrace it, thus, endowing it with a practical advantage over existing methodologies