반응 #7751

반응 방정식

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

trimethylacetyl chloride

Dichloro-methane

→

desired product

수율 98.0%

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

수율 98.0%

용매

pyridine

반응 조건

후처리

1. 1
   기타The cloudy reaction mixture
2. 2
   농축is then concentrated in vacuo
3. 3
   기타to afford a white residue
4. 4
   세척the mixture washed with a 1.0 N aqueous solution of hydrochloric acid (75 mL)
5. 5
   추출The aqueous layer is extracted with dichloro-methane (75 mL)
6. 6
   세척the combined organic layers washed with a saturated aqueous solution of NaHCO3 (75 mL), water (75 mL), brine (75 mL)
7. 7
   기타dried
8. 8
   여과filtered
9. 9
   농축concentrated in vacuo
10. 10
    기타to afford the crude product
11. 11
    기타The crude product is purified over silica (4:1 to 1:1 hexane/ethyl acetate)

실험 절차

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.

출처