反応 #632004

反応方程式

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

溶媒

benzene

反応条件

後処理

1. 1
   温度The reaction mixture was heated
2. 2
   温度to reflux for 3.5 hours
3. 3
   温度heated
4. 4
   温度to reflux overnight
5. 5
   ろ過The reaction mixture was filtered
6. 6
   workup.ADDITIONdiluted with diethyl ether
7. 7
   洗浄washed sequentially with 10% aqueous citric acid solution, water, saturated aqueous NaHCO3, water (2×), and brine (2×)
8. 8
   乾燥dried (MgSO4)
9. 9
   ろ過filtered
10. 10
    濃縮concentrated in vacuo
11. 11
    ろ過filtered

実験手順

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).

出典