Benzene → (1S,2S) 2-Ethyl-1-(2trimethylsilanylethoxycarbonylamino)cyclopropane-carboxylic acid tert-butyl ester

To a suspension, of the product of Step 2 (10 g, 46.8 mmol) and 3 g of freshly activated 4A molecular sieves in dry benzene (160 mL), was added Et3N (7.50 mL, 53.8 mmol) and DPPA (11 mL, 10.21 mmol). The reaction mixture was refluxed for 3.5 h, 2-trimethylsilyl-ethanol (13.5 mL, 94.2 mmol) was then added, and the reaction mixture was refluxed overnite. The reaction mixture was filtered, diluted with Et2O, washed with a 10% aqueous citric acid solution, water, saturated aqueous NaHCO3, water (2×), brine (2×), dried (MgSO4) and concentrated in vacuo. The residue was suspended with 10 g of Aldrich polyisocyanate scavenger resin in 120 mL of CH2Cl2, stirred at rt overnite and filtered to afford the titled 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 (bm, 1H), 1.45 (s, 9H), 1.40-1.70 (m, 4H), 4.16 (m, 2H), 5.30 (bs, 1H).

1. temperatureThe reaction mixture was refluxed for 3.5 h
2. temperaturethe reaction mixture was refluxed overnite
3. filtrationThe reaction mixture was filtered
4. additiondiluted with Et2O
5. washwashed with a 10% aqueous citric acid solution, water, saturated aqueous NaHCO3, water (2×), brine (2×)
6. dry with materialdried (MgSO4)
7. concentrationconcentrated in vacuo
8. filtrationfiltered

ORDレコード

ord-a5b5b80c7fc6482aa8367aea65895be5

出典データセット

uspto-grants-2014_11

DOI

10.6084/m9.figshare.5104873.v1

特許番号

US08889871B2