Pinacol → 5-(Tetramethyl-1,3,2-dioxaborolan-2-yl)-2-(tris(propan-2-yl)silyl)-1,3-oxazole

HRID 927011Notes

Reaction equation

[CH:1]([Si:4]([CH:13]([CH3:15])[CH3:14])([CH:10]([CH3:12])[CH3:11])[C:5]1[O:6][CH:7]=[CH:8][N:9]=1)([CH3:3])[CH3:2].C([Li])CCC.[BH:21]([OH:23])[OH:22].O[C:25]([CH3:31])([C:27](O)([CH3:29])[CH3:28])[CH3:26]>C1COCC1.C(OCC)C.C(O)(=O)C>[CH3:26][C:25]1([CH3:31])[C:27]([CH3:29])([CH3:28])[O:23][B:21]([C:7]2[O:6][C:5]([Si:4]([CH:1]([CH3:3])[CH3:2])([CH:10]([CH3:12])[CH3:11])[CH:13]([CH3:15])[CH3:14])=[N:9][CH:8]=2)[O:22]1

Participants

Conditions

Temperature: -78 °C

Procedure

2-Triisopropylsilanyl-oxazole (intermediate 16, 10 g, 44.365 mmol) is dissolved in 40 mL abs. diethylether under argon. The solution is cooled to −78° C. and n-butyllithium (1.6 M solution in hexane, 100 mL, 160 mmol) is added slowly at that temperature. After stirring for 1 h boronic acid triispropylester (12 mL, 52.193 mmol) 20 mL abs. THF is added slowly. The mixture is stirred for 2 h, and is warmed to r.t. The mixture is quenched with methanol. 2,3-Dihydroxy-2,3-dimethylbutane (pinacole, 5.243 g, 44.365 mmol) is dissolved in 10 mL THF and injected to the mixture at 18° C. within 3 min. The mixture is acidified to pH 5 with acetic acid and stirred for 12 h. After addition of 150 mL diethylether and filtration over silica gel, the solvent is evaporated in vacuo. Yield: 15.2 g; ESI mass spectrum: [M+H]+=352; retention time HPLC: 1.334 min (HPLC method Z001_002).

Workup

temperatureis warmed to r.t
customThe mixture is quenched with methanol
waitinjected to the mixture at 18° C. within 3 min
stirringstirred for 12 h
customthe solvent is evaporated in vacuo
custom1.334 min (HPLC method Z001_002)

Sources & evidence

ORD record: ord-5694f08876f04c02bbc3dbf3333e7005
Source dataset: uspto-grants-2016_03
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09290457B2

Reaction notes

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