Bis(pinacolato)diborane → 5-Chloro-6-cyclopropylpyridin-3-OL

Participants

Reaction Steps

A round bottom flask was charged with 3-chloro-2-cyclopropylpyridine (Preparation 48, 0.475 g; 3.092 mmol), bis(pinacolato)diboron (0.980 g, 3.859 mol) and 4,4-di-tert-butyl-2,2-dipyridyl (0.025 g; 0.093 mmol) in heptane (1.55 L). The reaction mixture was cycled between vacuum and nitrogen 6 times over 15 minutes. Di-methanolatodiiridium(Ir—Ir)-cycloocta-1,5-diene (1:2) (0.063 g; 0.093 mmol) was then added and the reaction stirred for 18 hours under nitrogen atmosphere at room temperature. The reaction mixture was evaporated to dryness to afford a red viscous oil. The resulting oil was dissolved in acetone (10.0 mL) and cooled to 0° C. with an ice bath. Then potassium peroxymonosulfate (2.55 g, 4.15 mmol) in water (10.0 mL) was added dropwise to the mixture and stirred at this temperature for 1 hour. The reaction was then diluted in tert-butyl methyl ether (25.0 mL) and washed with brine (3×25.0 mL). The organic layer was then dried over sodium sulfate, filtered, and concentrated in vacuo. The resulting crude product was purified with silica gel chromatography eluting with 0 to 30% EtOAc in heptane to yield the title compound as a pale yellow solid (0.220 g, 1.28 mmol, 42%):

Provenance & Evidence