Cesium carbonate → Z-Sta-OMe
Reaktionsgleichung
[NH:1]([C:13]([O:15][CH2:16][C:17]1[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=1)=[O:14])[C@H:2]([C@H:7]([CH2:9][C:10]([OH:12])=[O:11])[OH:8])[CH2:3][CH:4]([CH3:6])[CH3:5].[C:23](=O)([O-])[O-].[Cs+].[Cs+]>CO>[NH:1]([C:13]([O:15][CH2:16][C:17]1[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=1)=[O:14])[C@H:2]([C@H:7]([CH2:9][C:10]([O:12][CH3:23])=[O:11])[OH:8])[CH2:3][CH:4]([CH3:6])[CH3:5]Komponenten
4
Reagenzien, Katalysatoren, Lösungsmittel 1
Reaktionsbedingungen
- Temperatur
- 25 °C
Versuchsvorschrift
250 mg of Z-Sta-OH(cf. stage 1.12) are dissolved in 4 ml of 90% strength methanol. 1 ml of a 20% aqueous cesium carbonate solution is added to the solution, and the solvent is then removed in a rotary evaporator. The residue is twice dissolved in 2.5 ml of DMF and each time the DMF is removed again in a rotary evaporator. The residue is dried in a high vacuum, then dissolved in 2.5 ml of DMF and 55 μl of methyl iodide are added to the solution. The whole is stirred for 18 hours at 25° C., the solvent is then removed and the residue is taken up in ethyl acetate. After extraction twice with sodium chloride solution, the organic phase is dried over sodium sulphate and concentrated by evaporation. The residue is flash-chromatographed over 55 g of silica gel (eluant: chloroform/methanol [95:5]). The product-containing fractions are combined and concentrated by evaporation, yielding Z-Sta-OMe in the form of a yellowish oil; Rf (chloroform/methanol [95:5])=0.49.