Boron trifluoride → HCID 23568484, compound

Participants

Reaction Steps

To a solution of ethyl(2S)-N-tert-butoxycarbonyl-5-methoxyprolinate (4.10 g, 15.81 mmol) in CH2Cl2 (40 mL) at −50° C. was added trimethylsilyl cyanide (6.3 mL, 47.4 mmol) and BF3 etherate (5.60 mL, 47.4 mmol). The mixture was stirred from −50° C. to −30° C. for 2.0 h before it was quenched with saturated NaHCO3. The organic layer was separated and the aqueous phase was extracted with CH2Cl2. The combined organic layers were washed with brine and dried over MgSO4. Filtration, evaporation of solvent and flash column chromatography (hexane/ethyl acetate, 3:1) gave separated cis and tran isomers (2.20 g). 1HNMR (300 MHz, CDCl3) δ isomer 1: 4.68 (dd, J=4.0, 2.0 Hz) and 4.55 (t, J=5.4 Hz) for 1H, 4.40 (t, J=7.7 Hz) and 4.26 (t, J=6.9 Hz) for 1H, 3.79 (s, 3H), 2.42–1.98 (m, 4H), 1.52 (s) and 1.44 (s) for 9 H; isomer 2: 4.78 (dd, J=8.8, 1.5 Hz) and 4.67 (d, J=8.0 Hz) for 1H, 4.45 (d, J=8.8 Hz) and 4.34 (d, J=8.0 Hz) for 1H, 3.75 (s) and 3.73 (s) for 3H, 2.56–2.12 (m, 4H), 1.52 (s) and 1.43 (s) for 9H; CIMS 255 (M+H).

Provenance & Evidence