反応 #7751

反応方程式

4-Hydroxypyrazolidine-1,2-dicarboxylic acid 1-benzyl ester 2-tert-butyl ester

trimethylacetyl chloride

Dichloro-methane

→

desired product

収率 98.0%

4-(2,2-dimethylpropionyloxy)pyrazolidine-1,2-dicarboxylic acid 1-benzyl ester 2-tert-butyl ester

収率 98.0%

溶媒

pyridine

反応条件

後処理

1. 1
   その他The cloudy reaction mixture
2. 2
   濃縮is then concentrated in vacuo
3. 3
   その他to afford a white residue
4. 4
   洗浄the mixture washed with a 1.0 N aqueous solution of hydrochloric acid (75 mL)
5. 5
   抽出The aqueous layer is extracted with dichloro-methane (75 mL)
6. 6
   洗浄the combined organic layers washed with a saturated aqueous solution of NaHCO3 (75 mL), water (75 mL), brine (75 mL)
7. 7
   その他dried
8. 8
   ろ過filtered
9. 9
   濃縮concentrated in vacuo
10. 10
    その他to afford the crude product
11. 11
    その他The crude product is purified over silica (4:1 to 1:1 hexane/ethyl acetate)

実験手順

4-Hydroxypyrazolidine-1,2-dicarboxylic acid 1-benzyl ester 2-tert-butyl ester, 28, (1.42 mg, 4.40 mmol) is dissolved in pyridine (22 mL). 4-Dimethylamino-pyridine (10 mg) is added followed by trimethylacetyl chloride (1.63 mL, 13.2 mmol). The reaction is stirred at ambient temperature for 12 hours. The cloudy reaction mixture is then concentrated in vacuo to afford a white residue. Dichloro-methane (75 mL) is added to the residue and the mixture washed with a 1.0 N aqueous solution of hydrochloric acid (75 mL). The aqueous layer is extracted with dichloro-methane (75 mL), the combined organic layers washed with a saturated aqueous solution of NaHCO3 (75 mL), water (75 mL), brine (75 mL), then dried, filtered and concentrated in vacuo to afford the crude product. The crude product is purified over silica (4:1 to 1:1 hexane/ethyl acetate) to afford 1.76 g (98% yield) of the desired product as a clear, viscous oil.

出典