Tantalum Catalyzed Hydroaminoalkylation for the Synthesis of α- and β‑Substituted N‑Heterocycles

Unprotected secondary amines are directly alkylated by C–H functionalization adjacent to nitrogen, thereby opening new routes toward the synthesis of α- and β-alkylated N-heterocycles. α-Alkylated piperidine, piperazine, and azepane products are prepared from heterocycles and alkenes in an atom-economic reaction with excellent regio- and diastereoselectivity. β-Alkylated N-heterocycles are synthesized via a scalable one-pot alkylation/cyclization procedure generating 3-methylated azetidines, pyrrolidines, and piperidines.