2-Bromo-3-methylthiophene → 4,4,5,5-Tetramethyl-2-(3-methylthiophen-2-yl)-1,3,2-dioxaborolane
Reaction equation
Br[C:2]1[S:3][CH:4]=[CH:5][C:6]=1[CH3:7].[Li]CCCC.C(O[B:17]1[O:21][C:20]([CH3:23])([CH3:22])[C:19]([CH3:25])([CH3:24])[O:18]1)(C)C>C1COCC1>[CH3:24][C:19]1([CH3:25])[C:20]([CH3:23])([CH3:22])[O:21][B:17]([C:2]2[S:3][CH:4]=[CH:5][C:6]=2[CH3:7])[O:18]1Participants
Procedure
To a stirred solution of 2-bromo-3-methythiophene (337 mg, 1.9 mmol) in 8 mL of THF at −40° C. was added n-BuLi (0.8 mL, 2.5 M/hexanes), and the reaction was allowed to stir for 30 min. At this time 2-isopropoxy-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane (775 μL, 3.8 mmol) was added, and the reaction was allowed to warm to ambient temperature, and stirring was continued for 1 h. The reaction was then cooled to 0° C. and quenched with satd aq NaHCO3 (10 mL). The mixture was poured into EtOAc (100 mL), washed with H2O (2×50 mL), dried (Na2SO4) and concentrated in vacuo. Purification of the residue by silica gel preparative thin layer chromatography (20% EtOAc-hexanes) afforded 224 mg (53%) of the title compound as an oil. 1H-NMR (CDCl3; 400 MHz): δ 1.36 (s, 12H), 2.5 (s, 3H), 6.99 (d, 1H, J=4.8 Hz), 7.50 (d, 1H, J=4.8 Hz).
Workup
- stirringstirring
- waitwas continued for 1 h
- temperatureThe reaction was then cooled to 0° C.
- customquenched with satd aq NaHCO3 (10 mL)
- additionThe mixture was poured into EtOAc (100 mL)
- washwashed with H2O (2×50 mL)
- dry with materialdried (Na2SO4)
- concentrationconcentrated in vacuo
- customPurification of the residue by silica gel preparative thin layer chromatography (20% EtOAc-hexanes)
Sources & evidence
- ORD record
- ord-7c2affbb7c814cb19c9e1469a896b75c
- Source dataset
- uspto-grants-2010_01
- Patent number
- US07645755B2
Reaction notes
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