Enantioselective Synthesis of Pyrrolidine-, Piperidine-, and Azepane-Type <i>N</i>-Heterocycles with α-Alkenyl Substitution: The CpRu-Catalyzed Dehydrative Intramolecular <i>N</i>-Allylation Approach

A cationic CpRu complex of chiral picolinic acid derivatives [(<i>R</i>)- or (<i>S</i>)-Cl-Naph-PyCOOCH₂CHCH₂] catalyzes asymmetric intramolecular dehydrative <i>N</i>-allylation of <i>N</i>-substituted ω-amino- and -aminocarbonyl allylic alcohols with a substrate/catalyst ratio of up to 2000 to give α-alkenyl pyrrolidine-, piperidine-, and azepane-type <i>N</i>-heterocycles with an enantiomer ratio of up to >99:1. The wide range of applicable <i>N</i>-substitutions, including Boc, Cbz, Ac, Bz, acryloyl, crotonoyl, formyl, and Ts, significantly facilitates further manipulation toward natural product synthesis