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

82800

Sigma-Aldrich

Pyridine hydrochloride, purum, ≥98.0% (AT)

349208

Sigma-Aldrich

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

243086

Sigma-Aldrich

Pyridine hydrochloride, 98%

207780

Sigma-Aldrich

Copper, powder, <75 μm, 99%

326488

Sigma-Aldrich

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

254177

Sigma-Aldrich

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

BCR058

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

61139

Sigma-Aldrich

Copper, turnings, purum p.a., ≥99.0%

349224

Sigma-Aldrich

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

349151

Sigma-Aldrich

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

266744

Sigma-Aldrich

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

12816

Sigma-Aldrich

Copper, foil, ≥99.8% (complexometric)

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

48305-U

Supelco

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

349216

Sigma-Aldrich

Copper, wire, diam. 1.0 mm, ≥99.9%

275778

Sigma-Aldrich

Imidazo[1,2-a]pyridine, 99%

BCR017B

Copper (S, P), BCR^®, certified reference material, chips

IRMM522C

Copper, IRMM^®, certified reference material, 0.5 mm wire

IRMM522A

Copper, IRMM^®, certified reference material, 0.1 mm foil

W296600

Sigma-Aldrich

Pyridine, ≥99%

223409

Sigma-Aldrich

Copper, shot, −3-+14 mesh, 99%

203122

Sigma-Aldrich

Copper, powder, 99.999% trace metals basis

349178

Sigma-Aldrich

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

266086

Sigma-Aldrich

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

357456

Sigma-Aldrich

Copper, powder (dendritic), <45 μm, 99.7% trace metals basis

270970

Sigma-Aldrich

Pyridine, anhydrous, 99.8%

311405

Sigma-Aldrich

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

BCR054R

Copper (O), BCR^®, certified reference material, rod

326453

Sigma-Aldrich

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