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

Participants

Reaction Steps

To a suspension of the product of Step 6b (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 refluxed for 3.5 hours, 2-trimethylsilyl-ethanol (13.5 mL, 94.2 mmol) was then added, and the reaction mixture was refluxed overnight. The reaction mixture was filtered, diluted with diethyl ether, washed with a 10% aqueous citric acid solution, water, saturated aqueous NaHCO3, water (2×), 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 CH2Cl2, 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 (bm, 1H), 1.45 (s, 9H), 1.40-1.70 (m, 4H), 4.16 (m, 2H), 5.30 (br s, 1H).

Provenance & Evidence