Triisopropyl borate → 6-(Boc-methylamino)pyridine-3-boronic acid pinacol ester

HRID 1365399Notes

Reaction equation

[C:1]([O:5][C:6](=[O:16])[N:7]([C:9]1[CH:14]=[CH:13][C:12](Br)=[CH:11][N:10]=1)[CH3:8])([CH3:4])([CH3:3])[CH3:2].C([Li])CCC.[B:22]([O:31][CH:32]([CH3:34])[CH3:33])([O:27][CH:28]([CH3:30])[CH3:29])OC(C)C.OCC(C)(CO)C>C1COCC1>[C:1]([O:5][C:6](=[O:16])[N:7]([CH3:8])[C:9]1[CH:14]=[CH:13][C:12]([B:22]2[O:27][C:28]([CH3:29])([CH3:30])[C:32]([CH3:33])([CH3:34])[O:31]2)=[CH:11][N:10]=1)([CH3:4])([CH3:3])[CH3:2]

Participants

Conditions

Temperature: -78 °C

Procedure

To a solution of (5-bromo-pyridin-2-yl)-methyl-carbamic acid tert-butyl ester (3.286 g) in THF (50 mL) at −78° C. was added n-butyllithium (5.15 mL of a 2.5 M solution in hexanes). After stirring at −78° C. for 20 min, triisopropyl borate (5.31 mL) was added. The reaction was warmed to −45° C. over 4 h, then, neopentyl glycol (1.19 g) was added. The reaction was warmed to room temperature over 16 h and then quenched with ice/water (70 mL) and extracted into dichloromethane (3×40 mL). The organic layers were dried (MgSO4), reduced in vacuo and purified on silica to give methyl-[5-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-pyridin-2-yl]-carbamic acid tert-butyl ester as an off-white solid.

Workup

temperatureThe reaction was warmed to −45° C. over 4 h
temperatureThe reaction was warmed to room temperature over 16 h
customquenched with ice/water (70 mL)
extractionextracted into dichloromethane (3×40 mL)
dry with materialThe organic layers were dried (MgSO4)
custompurified on silica

Sources & evidence

ORD record: ord-c2eb77a2de56434481e050b7ace476d4
Source dataset: uspto-grants-2011_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07888352B2

Reaction notes

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