反応 #159448

反応方程式

trimethyl borate

3-(2-ethyl-5-iodophenyl)bicyclo[3.2.1]octane-2,4-dione

iso-propyl magnesium chloride lithium chloride

→

3-(2,4-dioxo-bicyclo[3.2.1]oct-3-yl)-4-ethylphenylboronic acid

収率 90.8%

溶媒

dichloromethane

tetrahydrofuran

反応条件

後処理

1. 1
   workup.ADDITIONis added dropwise
2. 2
   温度to maintain a temperature below −60° C
3. 3
   workup.STIRRINGis further stirred for 5 minutes
4. 4
   workup.WAITadditionally at room temperature for 1 hour
5. 5
   その他The solution is quenched with 2M hydrochloric acid
6. 6
   抽出extracted with ethyl acetate (×3)
7. 7
   乾燥dried over magnesium sulfate
8. 8
   ろ過filtered
9. 9
   濃縮the filtrate concentrated in vacuo
10. 10
    その他to give an orange-coloured gum
11. 11
    その他then precipitated with iso-hexane

実験手順

To a solution of 3-(2-ethyl-5-iodophenyl)bicyclo[3.2.1]octane-2,4-dione (0.65 g, 1.77 mmol) in anhydrous tetrahydrofuran (15 ml) at −10° C. is added iso-propyl magnesium chloride lithium chloride complex (10.6 ml, 10.6 mmol, 1M in tetrahydrofuran) dropwise over 10 minutes. The reaction mixture is stirred at this temperature for 1.5 hours, then cooled to −78° C., at which point trimethyl borate (1.39 ml, 12.4 mmol) is added dropwise to maintain a temperature below −60° C. After re-cooling to −78° C. the mixture is further stirred for 5 minutes, then additionally at room temperature for 1 hour. The solution is quenched with 2M hydrochloric acid and extracted with ethyl acetate (×3). All organic fractions are combined, dried over magnesium sulfate, filtered and the filtrate concentrated in vacuo to give an orange-coloured gum. This crude product is dissolved in a minimum amount of dichloromethane then precipitated with iso-hexane to afford 3-(2,4-dioxo-bicyclo[3.2.1]oct-3-yl)-4-ethylphenylboronic acid (0.46 g, 90%) as a cream-coloured solid.

出典