تفاعل #632004

معادلة التفاعل

2-trimethylsilyl-ethanol

triethylamine

DPPA

product

racemic 2-Ethylcyclopropane-1,1-dicarboxylic acid tert-butyl ester

→

desired product

(1S,2S) 2-ethyl-1-(2-trimethylsilanylethoxycarbonylamino)cyclopropane-carboxylic acid tert-butyl ester

المذيبات

benzene

ظروف التفاعل

المعالجة

1. 1
   درجة الحرارةThe reaction mixture was heated
2. 2
   درجة الحرارةto reflux for 3.5 hours
3. 3
   درجة الحرارةheated
4. 4
   درجة الحرارةto reflux overnight
5. 5
   ترشيحThe reaction mixture was filtered
6. 6
   workup.ADDITIONdiluted with diethyl ether
7. 7
   غسيلwashed sequentially with 10% aqueous citric acid solution, water, saturated aqueous NaHCO3, water (2×), and brine (2×)
8. 8
   تجفيفdried (MgSO4)
9. 9
   ترشيحfiltered
10. 10
    تركيزconcentrated in vacuo
11. 11
    ترشيحfiltered

الإجراء التجريبي

To a suspension of the product of Step 2 (10 g, 46.8 mmol) and 3 g of freshly activated 4 Å molecular sieves in dry benzene (160 mL) was added triethylamine (7.50 mL, 53.8 mmol) and DPPA (11 mL, 10.21 mmol). The reaction mixture was heated to reflux for 3.5 hours, treated with 2-trimethylsilyl-ethanol (13.5 mL, 94.2 mmol), and heated to reflux overnight. The reaction mixture was filtered, diluted with diethyl ether, washed sequentially with 10% aqueous citric acid solution, water, saturated aqueous NaHCO3, water (2×), and brine (2×), dried (MgSO4), filtered, and concentrated in vacuo. The residue was suspended with 10 g of Aldrich polyisocyanate scavenger resin in 120 mL of dichloromethane, stirred at room temperature overnight, and filtered to provide the desired product (8 g, 24.3 mmol; 52%) as a pale yellow oil: 1H NMR (CDCl3) δ 0.03 (s, 9H), 0.97 (m, 5H), 1.20 (br m, 1H), 1.45 (s, 9H), 1.40-1.70 (m, 4H), 4.16 (m, 2H), 5.30 (br s, 1H).

المصدر