반응 #632004

반응 방정식

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

용매

benzene

반응 조건

후처리

1. 1
   온도The reaction mixture was heated
2. 2
   온도to reflux for 3.5 hours
3. 3
   온도heated
4. 4
   온도to reflux overnight
5. 5
   여과The reaction mixture was filtered
6. 6
   workup.ADDITIONdiluted with diethyl ether
7. 7
   세척washed sequentially with 10% aqueous citric acid solution, water, saturated aqueous NaHCO3, water (2×), and brine (2×)
8. 8
   건조dried (MgSO4)
9. 9
   여과filtered
10. 10
    농축concentrated in vacuo
11. 11
    여과filtered

실험 절차

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).

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