Pinacol → 5-Pentylthiophene-2-boronic acid pinacol ester
Reaction equation
[CH2:1]([C:6]1[S:7][CH:8]=[CH:9][CH:10]=1)[CH2:2][CH2:3][CH2:4][CH3:5].OC(C(O)(C)C)(C)C.[Li]CCCC.[B:24]([O:33][CH:34]([CH3:36])[CH3:35])([O:29][CH:30]([CH3:32])[CH3:31])OC(C)C>C1COCC1.CCCCCC>[CH3:36][C:34]1([CH3:35])[C:30]([CH3:31])([CH3:32])[O:29][B:24]([C:8]2[S:7][C:6]([CH2:1][CH2:2][CH2:3][CH2:4][CH3:5])=[CH:10][CH:9]=2)[O:33]1Participants
7
Conditions
- Temperature
- -78 °C
Procedure
To a cooled (−78° C.) mixture of 2-n-pentylthiophene (5.0 g, 32.1 mmol) and pinacol (11.5 g, 97.23 mmol) in anhydrous THF (60 mL) was added dropwise to a solution of n-BuLi (22.3 mL, 35.6 mmol) in hexane. The mixture was stirred at −78° C. for 10 minute. The reaction mixture was then brought to 0° C. and stirred for 1 h before cooling to −78° C. before the addition of triisopropyl borate (7.3 g, 38.9 mmol) in THF (24 mL) using a dropping funnel. The mixture was slowly brought to room temperature while stirring overnight. The crude product was purified by flash chromatography (silica gel. eluent: hexane/EA) 10:1) to afford a reddish brown liquid 7.35 g (81.0%).
Workup
- temperatureTo a cooled
- customwas then brought to 0° C.
- stirringstirred for 1 h
- customwas slowly brought to room temperature
- stirringwhile stirring overnight
- customThe crude product was purified by flash chromatography (silica gel. eluent: hexane/EA) 10:1)
Sources & evidence
- ORD record
- ord-0020982e5b054020aa96dc737978f81a
- Source dataset
- uspto-grants-2013_02
- Patent number
- US08367717B2
Reaction notes
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