Tandem Amination/Cycloisomerization of Aryl Propargylic Alcohols with 2-Aminopyridines as an Expedient Route to Imidazo[1,2-a]pyridines

• Published in: European Journal of Organic Chemistry 2011-12, Vol.2011 (36), p.7308-7316
• Main Authors: Liu, Ping, Deng, Chun-Lin, Lei, Xinsheng, Lin, Guo-qiang
• Format: Article
• Language: English
• Subjects: Alk­ynes; Chemistry; Cycloisomerization; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with only one n hetero atom and condensed derivatives; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Medicinal chemistry; Nitrogen heterocycles; Organic chemistry; Preparations and properties; Synthesis design
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201101053

A new tandem route leading to imidazo[1,2‐a]pyridines has been explored through the direct amination of aryl propargylic alcohols with 2‐aminopyridines and their subsequent intramolecular cycloisomerization. A ZnCl2/CuCl system has been developed to promote this transformation, which resulted in various imidazo[1,2‐a]pyridines in moderate to good yields. All roads lead to Rome! Imidazo[1,2‐a]pyridines can be prepared from 2‐aminopyridines, aldehydes, and alkynes or from the opposite sequence of the two steps, thereby aryl propargylic alcohols were firstly prepared from aldehydes and alkynes and then directly converted into imidazo[1,2‐a]pyridines in moderate to good yields.