[NH:1]([C:11]([O:13][CH2:14][CH:15]1[C:27]2[C:22](=[CH:23][CH:24]=[CH:25][CH:26]=2)[C:21]2[C:16]1=[CH:17][CH:18]=[CH:19][CH:20]=2)=[O:12])[C@H:2]([C:8]([OH:10])=[O:9])[CH2:3][CH2:4][C:5](=[O:7])[NH2:6].[C:28]1([C:34]([C:42]2[CH:47]=[CH:46][CH:45]=[CH:44][CH:43]=2)([C:36]2[CH:41]=[CH:40][CH:39]=[CH:38][CH:37]=2)O)[CH:33]=[CH:32][CH:31]=[CH:30][CH:29]=1.S(=O)(=O)(O)O.C(OC(=O)C)(=O)C>C(O)(=O)C>[NH:1]([C:11]([O:13][CH2:14][CH:15]1[C:27]2[C:22](=[CH:23][CH:24]=[CH:25][CH:26]=2)[C:21]2[C:16]1=[CH:17][CH:18]=[CH:19][CH:20]=2)=[O:12])[C@H:2]([C:8]([OH:10])=[O:9])[CH2:3][CH2:4][C:5](=[O:7])[NH:6][C:34]([C:28]1[CH:33]=[CH:32][CH:31]=[CH:30][CH:29]=1)([C:42]1[CH:43]=[CH:44][CH:45]=[CH:46][CH:47]=1)[C:36]1[CH:37]=[CH:38][CH:39]=[CH:40][CH:41]=1A mixture of 7.4 g of Fmoc-Gln-OH (20 mmol) and 10.4 g of triphenylmethanol (40 mmol) in 300 ml of acetic acid is stirred at 100° for 10 minutes. After the addition of 0.1 ml of concentrated sulfuric acid the whole is stirred at 100° for a further 15 minutes, a clear yellow solution forming. This is concentrated by evaporation under reduced pressure at 60°, and the residue is dried under reduced pressure for 10 minutes. The solid residue is dissolved in 60 ml of acetic acid at 60°, left at 60° for 20 minutes, then 2 ml of acetic anhydride (20 mmol) are added and after 1 hour at 60° the whole is concentrated by evaporation under reduced pressure. The oily residue is dried for 10 minutes at 60°, then dissolved in 100 ml of acetic acid and introduced dropwise into 500 ml of ice-cold water. The precipitate is isolated by filtration, washed well with water and dissolved in ethyl acetate; the aqueous phase is separated off and the organic phase is washed with a saturated aqueous sodium chloride solution. After drying over sodium sulfate, the organic solution is concentrated to dryness by evaporation, the residue is dissolved in 50 ml of 1,2-dichloroethane and applied to 100 g of silica gel; elution is carried out with 1,2-dichloroethane and with 1,2-dichloroethane containing 2%, then 4%, methanol. The fractions containing the Fmoc-Gln(Trt)-OH are concentrated by evaporation under reduced pressure, and the product is crystallised from a mixture of ethyl acetate and diisopropyl ether, m.p. from 125°.
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