Triisopropyl borate → (4-(Tert-butoxycarbonyl)-2,3,4,5-tetrahydrobenzo[f][1,4]oxazepin-7-yl)boronic acid

Temperature

-78 °C

A solution of 1,1-dimethylethyl 7-bromo-2,3-dihydro-1,4-benzoxazepine-4(5H)-carboxylate (30.0 g, 91.4 mmol) and triisopropyl borate (22.4 g, 119 mmol) in THF (300 mL) was cooled to −78° C., and a 2.5 M solution of n-butyllithium in hexanes (47.6 mL, 119 mmol) was added dropwise over 40 min at this temperature. The reaction mixture was stirred at −78° C. for an additional 30 min, then quenched by dropwise addition of 2 N hydrochloric acid (80 ml), and allowed to warm up to room temperature. Ethyl acetate (100 mL) and water (100 mL) were added, the organic layer was separated, and the aqueous layer was extracted with ethyl acetate (100 mL). The combined organic layers were washed with water, dried over sodium sulfate, and concentrated. Hexane (200 mL) was added to the residue and the mixture was stirred overnight. The precipitate was filtered, washed several times with hexane, and dried to give (4-{[(1,1-dimethylethyl)oxy]carbonyl}-2,3,4,5-tetrahydro-1,4-benzoxazepin-7-yl)boronic acid (23.4 g, 87%) as a colorless solid. MS (EI) for C14H20BNO5: 294 (MH+).

1. customquenched by dropwise addition of 2 N hydrochloric acid (80 ml)
2. temperatureto warm up to room temperature
3. additionEthyl acetate (100 mL) and water (100 mL) were added
4. customthe organic layer was separated
5. extractionthe aqueous layer was extracted with ethyl acetate (100 mL)
6. washThe combined organic layers were washed with water
7. dry with materialdried over sodium sulfate
8. concentrationconcentrated
9. additionHexane (200 mL) was added to the residue
10. stirringthe mixture was stirred overnight
11. filtrationThe precipitate was filtered
12. washwashed several times with hexane
13. customdried

ORD record

ord-d1886be1c6ec4c18bab1f3347627e088

Source dataset

uspto-grants-2014_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08648066B2