Triethylamine → Ethyl 1-Boc-3-pyrrolidinecarboxylate

Participants

Reaction Steps

1-(tert-butoxycarbonyl)pyrrolidine-3-carboxylic acid (28) (1.0 g, 0.0046 mol) and triethylamine (0.78 mL, 0.0056 mol) were dissolved in 20 mL tetrahydrofuran and cooled over ice water. Ethyl chloroformate (0.48 mL, 0.0051 mol) was added dropwise at 0-5° C. and the reaction was stirred for 30 minutes. A catalytic amount of dimethylaminopyridine was added followed by 5 mL ethanol and the mixture was warmed to room temperature and stirred for 1 hour. The mixture was concentrated and partitioned between water (50 mL) and ethyl acetate (1×100 mL). The aqueous layer was extracted with an additional 50 mL ethyl acetate. The combined organics were washed with 1×50 mL water, 1×25 mL saturated sodium chloride, and dried over Na2SO4. The dried organics were evaporated to an oil. The residue was chromatographed with 10 g silica gel, 20% ethyl acetate/hexanes, to obtain 0.92 g of clear colorless oil. MS (ESI) m/z 282 [M+K]+. NMR (CDCl3) δ 1.25-1.31 (t, 3H), 1.49 (s, 9H), 1.57 (s, 2H), 3.01-3.07 (m, 1H), 3.30-3.36 (m, 1H), 3.47-3.65 (m, 3H), 4.13-4.20 (m, 2H).

Provenance & Evidence