Issue 41, 2019

Synthesis of fused imidazo[1,2-a]pyridines derivatives through cascade C(sp2)–H functionalizations

Abstract

An efficient and convenient synthesis of diversely substituted naphtho[1′,2′:4,5]imidazo[1,2-a]-pyridine derivatives from the cascade reactions of 2-arylimidazo[1,2-a]pyridines with a-diazo carbonyl compounds via Rh(III)-catalyzed regioselective C(sp2)–H alkylation followed by intramolecular annulation is presented. Interestingly, when simple 2-arylimidazo[1,2-a]pyridines were used as the substrates, 5,6-disubstituted naphtho[1′,2′:4,5]imidazo[1,2-a]pyridines were efficiently obtained, whereas using 2-arylimidazo[1,2-a]pyridine-3-carbaldehydes as the substrates afforded naphtho[1′,2′:4,5]imidazo[1,2-a]-pyridine-5-carboxylates as the dominating products. Compared with literature methods for the synthesis of naphtho[1′,2′:4,5]imidazo[1,2-a]pyridine derivatives, the protocol presented herein has advantages such as easily obtainable substrates, simple operational procedure, high efficiency and excellent regio- and chemoselectivity.

Graphical abstract: Synthesis of fused imidazo[1,2-a]pyridines derivatives through cascade C(sp2)–H functionalizations

Supplementary files

Article information

Article type
Paper
Submitted
07 Aug 2019
Accepted
30 Sep 2019
First published
01 Oct 2019

Org. Biomol. Chem., 2019,17, 9140-9150

Synthesis of fused imidazo[1,2-a]pyridines derivatives through cascade C(sp2)–H functionalizations

B. Li, N. Shen, X. Zhang and X. Fan, Org. Biomol. Chem., 2019, 17, 9140 DOI: 10.1039/C9OB01744E

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