Triisopropyl borate → (2-(But-3-en-1-yl)phenyl)boronic acid

Ref Li, W., Nelson, D. P., Jensen, M. S., Hoerrner, R. S., Cai, D., Larsen, R. D., Reider, P. J. J. Org. Chem., 2002, 67, 5394-5397. A solution of 1-bromo-2-(but-3-en-1-yl)benzene (9.46 g, 44.8 mmol) in dry THF (44.8 ml) was cooled (−78° C.) and treated with 2.5 M n-BuLi in hexanes (19.7 ml, 49.3 mmol). The mixture was stirred for 20 min, and then treated with triisopropyl borate (51.5 ml, 224 mmol). After 90 min, the reaction mixture was warmed to room temperature over 1 h. Then, the reaction was quenched with 2.0 N aq. HCl (240 mL), diluted with Et2O (120 mL), and the layers were stirred vigorously for several minutes. The resulting white precipitate was removed by filtration and then the filtrate layers were separated. The organic layer was dried (Na2SO4), filtered, and concentrated, affording a pale yellow oil which partially solidified upon standing. These solids were triturated with hexanes and then dried under vacuum. The decantate was concentrated to an oil, dissolved in fresh hexanes (˜15 mL) and stored (−40° C.) for 16 h. A second crop of solid was collected, washing with a small volume of hexanes, and dried under vacuum Both crops were combined to afford the desired product (5.46 g, 31.0 mmol, 69.2% yield) as a white crystalline solid. 1H NMR (500 MHz, CDCl3) δ 8.24 (dd, J=7.8, 1.3 Hz, 1H), 7.52 (td, J=7.5, 1.4 Hz, 1H), 7.30-7.36 (m, 2H), 5.96 (ddt, J=17.0, 10.3, 6.5 Hz, 1H), 5.04-5.10 (m, 1H), 5.02 (dd, J=10.2, 1.6 Hz, 1H), 3.29-3.40 (m, 2H), 2.50 (td, J=7.9, 6.6 Hz, 2H). LCMS (M−H)=175.11.

1. waitAfter 90 min
2. customThen, the reaction was quenched with 2.0 N aq. HCl (240 mL)
3. additiondiluted with Et2O (120 mL)
4. stirringthe layers were stirred vigorously for several minutes
5. customThe resulting white precipitate was removed by filtration
6. customthe filtrate layers were separated
7. dry with materialThe organic layer was dried (Na2SO4)
8. filtrationfiltered
9. concentrationconcentrated
10. customaffording a pale yellow oil which
11. customThese solids were triturated with hexanes
12. customdried under vacuum
13. concentrationThe decantate was concentrated to an oil
14. dissolutiondissolved in fresh hexanes (˜15 mL)
15. custom(−40° C.)
16. customfor 16 h
17. customA second crop of solid was collected
18. washwashing with a small volume of hexanes
19. customdried under vacuum Both crops

ORD record

ord-ed865bc0691a4bb6b26904ef10d1680c

Source dataset

uspto-grants-2014_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08906929B2