Synthesis of Disubstituted 3‑Phenylimidazo­[1,2‑a]­pyridines via a 2‑Aminopyridine/CBrCl3 α‑Bromination Shuttle

A versatile protocol for the synthesis of disubstituted 3-phenylimidazo­[1,2-a]­pyridines by coupling 2-aminopyridine with phenylaceto­phenones, phenylacetones, or β-tetralone has been developed. Isolated yields of up to 97% were obtained at 80 °C within 5 h. The 2-aminopyridine/CBrCl3 system acts a...

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Bibliographic Details
Published in:Journal of organic chemistry 2016-10, Vol.81 (19), p.9167-9174
Main Authors: Roslan, Irwan Iskandar, Ng, Kian-Hong, Wu, Ji’-En, Chuah, Gaik-Khuan, Jaenicke, Stephan
Format: Article
Language:English
Online Access:Get full text
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Summary:A versatile protocol for the synthesis of disubstituted 3-phenylimidazo­[1,2-a]­pyridines by coupling 2-aminopyridine with phenylaceto­phenones, phenylacetones, or β-tetralone has been developed. Isolated yields of up to 97% were obtained at 80 °C within 5 h. The 2-aminopyridine/CBrCl3 system acts as an α-bromination shuttle by transferring Br from CBrCl3 to the α-carbon of the carbonyl moiety. This triggers a series of steps with double C–N/C–N bond formation to the final product. The distinct advantages of this protocol include the use of commercially available inexpensive substrates, simplicity of a metal-free one-pot synthesis, and ease of scale-up to multigram quantities.
ISSN:0022-3263
1520-6904
DOI:10.1021/acs.joc.6b01714