Reaktion #79470

Reaktionsgleichung

diphenyldiazomethane

N-Boc-trans-4-hydroxy-L-proline

→

N-tert-butoxycarbonyl-trans-4-hydroxy-L-proline diphenylmethyl ester

Ausbeute 91.0%

Lösungsmittel

ethyl acetate

ethyl acetate

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeEvaporation of the solvent
2. 2
   Sonstigefollowed by precipitation of the product from ethyl acetate-petroleum ether b.p. 40-60° C.

Vorschrift

To a solution of freshly prepared diphenyldiazomethane22 (3.50 g, 18.0 mmol) in ethyl acetate (20 ml) was added N-Boc-trans-4-hydroxy-L-proline (3.25 g, 14.0 mmol) in ethyl acetate (30 ml). Nitrogen gas was slowly evolved from the solution and the intense purple colour of diphenyldiazomethane was gradually discharged. The solution was stirred at room temperature overnight using a CaCl2 guard tube. Evaporation of the solvent followed by precipitation of the product from ethyl acetate-petroleum ether b.p. 40-60° C. gave a white solid, N-tert-butoxycarbonyl-trans-4-hydroxy-L-proline diphenylmethyl ester (2a), (5.10 g, 91%), m.p. 93-95° C. (lit.9 m.p. 103-104° C.), δH (200 MHz; CDCl3) 1.22 and 1.47 (9H, 2×s, Boc rotamers), 1.95-2.50 [3H, br m, CH2(3) and OH], 3.45-3.74 [2H, br m, CH2(5)], 4.40-4.65 [2H, br m, CH(2)and CH(4)], 6.95 (1H, br s, CHPh2), 7.25-7.55 (10H, br m, phenyl CH); νmax (KBr)/cm−1 3491br (O—H), 1728s (C═O ester), 1693s (C═O urethane); m/z (ES MS) 436 (M+K+, 55%), 420 (M+Na+, 100), 415 (M+NH4+, 15), 398 (M+H+, 72); [α]D25−54.3 (C=1.0, EtOH).

Quelle