Reaktion #1073531

Reaktionsgleichung

benzyloxycarbonylasparagine

N-ethylpiperidine

phenylalanine methyl ester

N-ethylpiperidine

hydrochloride

pivaloylchloride

→

title product

Ausbeute 68.0%

Benzyloxycarbonylasparaginyl-phenylalanine methylester

Ausbeute 68.0%

Lösungsmittel

dichloromethane

pyridine

dichlormethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONis treated
2. 2
   workup.ADDITIONis added
3. 3
   workup.STIRRINGThe reaction mixture is stirred for an additional 2 hours at room temperature
4. 4
   Sonstigethe precipitated crystalline substance is collected
5. 5
   Filtrationon filter
6. 6
   Sonstigetriturated successively with 1 M hydrochloric acid, water, 5% aqueous sodium hydrogencarbonate solution and water
7. 7
   SonstigeCrystallization from methanol

Vorschrift

A solution of benzyloxycarbonylasparagine (13.3 g; 50 mmoles), N-ethylpiperidine (7.0 ml) and pyridine (5.0 ml) in dichloromethane (100 ml) cooled to -20° C. is treated under constant stirring with pivaloylchloride (6.3 ml); the mixture is then stirred and cooled (0° C.) for 8 minutes. After that, within 2 to 3 minutes, a solution of phenylalanine methyl ester, liberated from its hydrochloride (10.7 g; 50 mmoles) by the addition of N-ethylpiperidine (7.0 ml), in dichlormethane (100 ml) is added. The reaction mixture is stirred for an additional 2 hours at room temperature, the precipitated crystalline substance is collected on filter and triturated successively with 1 M hydrochloric acid, water, 5% aqueous sodium hydrogencarbonate solution and water. Crystallization from methanol yields 14.5 g (68%) of the title product, melting at 196° -197° C. An analytical sample is crystallized from dimethylformamide and 2-propanol, and the m.p. remains unchanged. Chromatography: Rf 0.71/S1, 0.75/S2. Optical rotation [α]D20 -2.0° (c 0.2; dimethylformamide). The elemental composition corresponds to the summary formula C22H25N3O6.

Quelle