Hydrochloric Acid → 6,7-Dichloro-2,3-dimethoxyquinoxaline-5-boronic acid
Reaction equation
O1CCCC1.C([N-]C(C)C)(C)C.[Li+].[Cl:14][C:15]1[CH:16]=[C:17]2[C:22](=[CH:23][C:24]=1[Cl:25])[N:21]=[C:20]([O:26][CH3:27])[C:19]([O:28][CH3:29])=[N:18]2.[B:30](OC)([O:33]C)[O:31]C.Cl>O1CCCC1.O>[Cl:25][C:24]1[C:15]([Cl:14])=[CH:16][C:17]2[N:18]=[C:19]([O:28][CH3:29])[C:20]([O:26][CH3:27])=[N:21][C:22]=2[C:23]=1[B:30]([OH:33])[OH:31]Participants
Reactant 4
Product 1
Reagents, catalysts & solvents 2
Procedure
Lithium diisopropylamide mono(tetrahydrofuran) (1.5M in cyclohexane, 6.18 mL, 9.26 mmol) was added to a stirred suspension of 6,7-dichloro-2,3-dimethoxyquinoxaline (Preparation 1, 2.0 g, 7.72 mmol) in dry tetrahydrofuran (150 mL) at −78° C., under nitrogen. After 1 hour at −78° C., trimethyl borate (1.47 mL, 2.0 g, 19.3 mmol) was added. The solution was stirred for a further 1 hour and then left to reach room temperature over 18 hours. Water (50 mL) was added, the solution was acidified to pH 1 with 2M aqueous hydrochloric acid solution and extracted with dichloromethane (3×150 mL). The combined organic extracts were dried (MgSO4) and concentrated under reduced pressure. The residue was purified by flash chromatography on silica gel, by gradient elution using dichloromethane:methanol (100:0 changing to 99:1, by volume) as the eluent to afford 6,7-dichloro-2,3-dimethoxyquinoxaline-5-boronic acid (0.610 g, 26%) as a light brown solid.
Workup
- waitleft
- waitto reach room temperature over 18 hours
- extractionextracted with dichloromethane (3×150 mL)
- dry with materialThe combined organic extracts were dried (MgSO4)
- concentrationconcentrated under reduced pressure
- customThe residue was purified by flash chromatography on silica gel, by gradient elution
Sources & evidence
- ORD record
- ord-e14c38ab15434c38a0149fee9cdf3a55
- Source dataset
- uspto-grants-2002_04
- Patent number
- US06376490B1
Reaction notes
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