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

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%):

1. customThe reaction mixture was evaporated to dryness
2. customto afford a red viscous oil
3. temperaturecooled to 0° C. with an ice bath
4. stirringstirred at this temperature for 1 hour
5. washwashed with brine (3×25.0 mL)
6. dry with materialThe organic layer was then dried over sodium sulfate
7. filtrationfiltered
8. concentrationconcentrated in vacuo
9. customThe resulting crude product was purified with silica gel chromatography
10. washeluting with 0 to 30% EtOAc in heptane

ORD-Eintrag

ord-a4a0b53c6c8243f0a28f8168afdd61b8

Quelldatensatz

uspto-grants-2013_11

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08592629B2