反応 #657315

反応方程式

3-bromo-2-(4-fluorophenyl)-7-methyl-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine

2-isopropyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

→

2-(4-fluorophenyl)-7-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine

収率 44.0%

溶媒

THF

THF

反応条件

後処理

1. 1
   workup.STIRRINGthe reaction mixture is stirred for 2 hours at −78° C
2. 2
   その他Then the reaction mixture is quenched by the addition of an aqueous solution of NH4Cl
3. 3
   抽出is extracted with EtOAc
4. 4
   洗浄The combined organic phases are washed with water and brine
5. 5
   乾燥dried over Na2SO4
6. 6
   濃縮concentrated in vacuo
7. 7
   その他The crude is purified by silica gel chromatography (eluent cyclohexane/ethyl acetate)

実験手順

To a solution of 3-bromo-2-(4-fluorophenyl)-7-methyl-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine (1.5 g, 4.82 mmol, 1 eq) in THF (40 ml) is added a solution of n-Buli (3.314 ml, 1.6 M, 5.30 mmol, 1.1 eq) dropwise at −78° C. After 20 min of stirring, a solution of 1.23 g of 2-isopropyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (7.23 mmol, 1.1 eq) in THF is added dropwise and the reaction mixture is stirred for 2 hours at −78° C. Then the reaction mixture is quenched by the addition of an aqueous solution of NH4Cl and is extracted with EtOAc. The combined organic phases are washed with water and brine, dried over Na2SO4 and concentrated in vacuo. The crude is purified by silica gel chromatography (eluent cyclohexane/ethyl acetate). 760 mg (42%) of 2-(4-fluorophenyl)-7-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine are obtained.

出典