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)

BCR058

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

12816

Sigma-Aldrich

Copper, foil, ≥99.8% (complexometric)

326488

Sigma-Aldrich

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

349208

Sigma-Aldrich

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

243086

Sigma-Aldrich

Pyridine hydrochloride, 98%

349216

Sigma-Aldrich

Copper, wire, diam. 1.0 mm, ≥99.9%

349151

Sigma-Aldrich

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

349224

Sigma-Aldrich

Copper, wire, diam. 2.0 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

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

326429

Sigma-Aldrich

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

207780

Sigma-Aldrich

Copper, powder, <75 μm, 99%

61139

Sigma-Aldrich

Copper, turnings, purum p.a., ≥99.0%

P57506

Sigma-Aldrich

Pyridine, ReagentPlus^®, ≥99%

16037

Sigma-Aldrich

Pyridine, ≥99.5% (GC)

774103

Sigma-Aldrich

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

33553

Sigma-Aldrich

Pyridine, puriss. p.a., ACS reagent, reag. Ph. Eur., ≥99.5% (GC)

494410

Sigma-Aldrich

Pyridine, biotech. grade, ≥99.9%

320498

Sigma-Aldrich

Pyridine, ReagentPlus^®, ≥99%

360570

Sigma-Aldrich

Pyridine, ACS reagent, ≥99.0%

774111

Sigma-Aldrich

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

W296600

Sigma-Aldrich

Pyridine, ≥99%

275778

Sigma-Aldrich

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

223409

Sigma-Aldrich

Copper, shot, −3-+14 mesh, 99%

203122

Sigma-Aldrich

Copper, powder, 99.999% trace metals basis

307475

Sigma-Aldrich

Pyridine hydrobromide, 98%

BCR054R

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