[C:1]([N:8]1[CH2:16][C:15]2[C:10](=[CH:11][CH:12]=[CH:13][CH:14]=2)[CH:9]1[C:17]([OH:19])=[O:18])([O:3][C:4]([CH3:7])([CH3:6])[CH3:5])=[O:2].[CH3:20][Si](C=[N+]=[N-])(C)C>C(Cl)Cl.CO>[C:1]([N:8]1[CH2:16][C:15]2[C:10](=[CH:11][CH:12]=[CH:13][CH:14]=2)[CH:9]1[C:17]([O:19][CH3:20])=[O:18])([O:3][C:4]([CH3:7])([CH3:6])[CH3:5])=[O:2]To a solution of N-BOC-1,3-dihydro-2H-isoindole-1-carboxylic acid (SNPE, 10 g, 38 mmol) in CH2Cl2 (100 mL) and MeOH (100 mL) at 0° C. was added trimethylsilyldiazomethane dropwise until the yellow color persisted. After stirring at rt for 15 min, the reaction mixture was concentrated in vacuo to dryness, and the residue was azeotroped with toluene to yield N-BOC-1,3-dihydro-2H-isoindole-1-carboxylic acid, methyl ester which was used without further purification.
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