In:
Organic & Biomolecular Chemistry, Royal Society of Chemistry (RSC), Vol. 20, No. 1 ( 2022), p. 219-227
Abstract:
Herein we report the synthesis of imidazo[1,5- a ]pyridine heterocycles via a Cu( ii )-mediated functionalization of α′-C(sp 3 )–H bonds of pyridinylaldimines and subsequent cyclization. This strategy exploits the inherent directing ability of heteroleptic aldimine and pyridine groups in the substrate yielding the C–H functionalization of α′-methylene groups in a regioselective fashion over distant methyl or methylene groups in β or γ positions. The observed correlation between the nature of the anionic ligands (halide vs. carboxylate) bonded to copper and the chemoselectivity of the C(sp 3 )–H activation process points to a concerted metalation–deprotonation pathway prior to cyclization to furnish the corresponding imidazo[1,5- a ]pyridine derivative. This copper-mediated C(sp 3 )–H bond functionalization reaction works for a variety of substrates incorporating linear alkyl chains (from 3 to 12 carbon atoms), and good functional group tolerance (aryl, ether and ester groups). Cu-Catalyzed C(sp 2 )–H cyanation on the imidazole ring can then take place selectively under oxidative conditions.
Type of Medium:
Online Resource
ISSN:
1477-0520
,
1477-0539
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
2097583-1
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