Conversion of pyridine to imidazo[1,2-a]pyridines by copper-catalyzed aerobic dehydrogenative cyclization with oxime esters.

Conversion of pyridine to imidazo[1,2-a]pyridines by copper-catalyzed aerobic dehydrogenative cyclization with oxime esters.

Organic letters (2013-11-23)

Huawen Huang, Xiaochen Ji, Xiaodong Tang, Min Zhang, Xianwei Li, Huanfeng Jiang

ABSTRACT

A rapid and environmentally friendly conversion of pyridine to imidazo[1,2-a]pyridines has been developed via copper-catalyzed aerobic dehydrogenative cyclization with ketone oxime esters.

MATERIALS

Product Number

Brand

Product Description

61139

Sigma-Aldrich

Copper, turnings, purum p.a., ≥99.0%

326488

Sigma-Aldrich

Copper, beads, 2-8 mm, ≥99.99% trace metals basis

326429

Sigma-Aldrich

Copper, wire, diam. 0.25 mm, 99.999% trace metals basis

326410

Sigma-Aldrich

Copper, wire, diam. 0.64 mm, 99.995% trace metals basis

349216

Sigma-Aldrich

Copper, wire, diam. 1.0 mm, ≥99.9%

82800

Sigma-Aldrich

Pyridine hydrochloride, purum, ≥98.0% (AT)

12816

Sigma-Aldrich

Copper, foil, ≥99.8% (complexometric)

207780

Sigma-Aldrich

Copper, powder, <75 μm, 99%

254177

Sigma-Aldrich

Copper, beads, 2-8 mm, 99.9995% trace metals basis

266744

Sigma-Aldrich

Copper, foil, thickness 1.0 mm, 99.999% trace metals basis

349151

Sigma-Aldrich

Copper, foil, thickness 0.5 mm, 99.98% trace metals basis

243086

Sigma-Aldrich

Pyridine hydrochloride, 98%

349208

Sigma-Aldrich

Copper, foil, thickness 0.025 mm, 99.98% trace metals basis

349224

Sigma-Aldrich

Copper, wire, diam. 2.0 mm, 99.999% trace metals basis

48305-U

Supelco

Pyridine solution, certified reference material, 2000 μg/mL in methanol

BCR058

Continuous cast copper (O), BCR^®, certified reference material, rod

275778

Sigma-Aldrich

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307475

Sigma-Aldrich

Pyridine hydrobromide, 98%

326453

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Copper, powder (spheroidal), 10-25 μm, 98%

266086

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Copper, powder, <425 μm, 99.5% trace metals basis

349178

Sigma-Aldrich

Copper, foil, thickness 0.25 mm, 99.98% trace metals basis

203122

Sigma-Aldrich

Copper, powder, 99.999% trace metals basis

311405

Sigma-Aldrich

Copper, ACS reagent, granular, 10-40 mesh, ≥99.90%

774103

Sigma-Aldrich

Copper, nanopowder, 60-80 nm particle size (SAXS), ≥99.5% trace metals basis

774111

Sigma-Aldrich

Copper, nanopowder, 40-60 nm particle size (SAXS), ≥99.5% trace metals basis

494410

Sigma-Aldrich

Pyridine, biotech. grade, ≥99.9%

223409

Sigma-Aldrich

Copper, shot, −3-+14 mesh, 99%

357456

Sigma-Aldrich

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676772

Sigma-Aldrich

Pyridine, ACS reagent, ≥99.0%

270407

Sigma-Aldrich

Pyridine, suitable for HPLC, ≥99.9%