[C:1]([O:5][C:6]([N:8]1[CH2:12][C:11](=O)[C@@H:10]([NH:14][C:15]([C:17]2[S:18][C:19]([Cl:22])=[CH:20][CH:21]=2)=[O:16])[CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[Cl-].[NH4+].CC[N:27](C(C)C)C(C)C.[BH4-].[Na+]>CCO.CCOC(C)=O.CC([O-])C.CC([O-])C.CC([O-])C.CC([O-])C.[Ti+4]>[C:1]([O:5][C:6]([N:8]1[CH2:9][CH:10]([NH:14][C:15]([C:17]2[S:18][C:19]([Cl:22])=[CH:20][CH:21]=2)=[O:16])[C@@H:11]([NH2:27])[CH2:12]1)=[O:7])([CH3:4])([CH3:3])[CH3:2]
35.2 A solution of 500 mg (S)-3-[(5-chloro-thiophene-2-carbonyl)-amino]-4-oxo-pyrrolidine-1-carboxylic acid tert-butyl ester in 20 ml EtOH was treated with 155 mg ammonium chloride, 0.49 ml Hünig's base and 0.86 ml tetraisopropyl orthotitanate. The reaction mixture was stirred for 5 hrs at 40° C. Then it was cooled to 0° C., treated with 110 mg NaBH4 and stirred at r.t. overnight. The mixture was diluted with EtOAc and washed with H2O. The organic layer was dried over MgSO4, filtered and concentrated. The crude product was purified by column chromatography (silica gel, gradient: CH2Cl2->CH2Cl2/MeOH 9:1) to give 180 mg (S)-3-amino-4-[(5-chloro-thiophene-2-carbonyl)-amino]-pyrrolidine-1-carboxylic acid tert-butyl ester as yellow solid. MS 344.3 ([M−H]−)
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