Toluene → Benzyloxycarbonyl-L-proline

Participants

Reaction Conditions

Reaction Steps

L-Proline (10 g, 86.6 mmol) was dissolved in 66 mL of 2N NaOH and cooled to 0° C. To this solution were slowly and simultaneously added 34.35 mL of a solution of phenyl chloroformate in toluene (104.2 mmol) and 33 mL of 4N NaOH, over a period of 1 hr, while maintaining the reaction temperature at 0° C. and the pH above 7. After all reactants were added, the reaction was stirred for 6 hr at room temperature. The solution was then extracted with ether. The remaining aqueous layer was neutralized to pH 6-7 with 1N HCl, then extracted with ethyl acetate. The extract was dried over Na2SO4 and concentrated to afford 21.19 g of the title product (98% yield). 1H NMR (CDCl3) δ 9.55 (d, 1H), 7.3 (s, 5H), 5.25 (d, 2H), 4.35 (t, 1H), 4.20 (t, 1H), 1.8-2.2 (m, 4H).

Provenance & Evidence