A 5 + 1 Protic Acid Assisted Aza-Pummerer Approach for Synthesis of 4‑Chloropiperidines from Homoallylic Amines

We
report that HCl·DMPU induces the formation of (thiomethyl)­methyl
carbenium ion from DMSO under mild conditions. Homoallylic amines
react with this electrophile to generate 4-chloropiperidines in good
yields. The method applies to both aromatic and aliphatic amines.
The use of HCl·DMPU as both non-nucleophilic base and chloride
source constitutes an environmentally benign alternative for piperidine
formation. The reaction has a broad substrate scope, and the conditions
offer good chemical yields with high functional group tolerance and
scalability.