Cl.[NH2:2][CH2:3][CH2:4][C:5]1[CH:13]=[CH:12][C:8]([C:9]([OH:11])=[O:10])=[CH:7][CH:6]=1.OS(O)(=O)=O.[CH3:19]O>>[NH2:2][CH2:3][CH2:4][C:5]1[CH:13]=[CH:12][C:8]([C:9]([O:11][CH3:19])=[O:10])=[CH:7][CH:6]=1To a solution of 2.02 g (10.0 mmol) of 4-(2-aminoethyl)benzoic acid hydrochloride in 25 mL of methanol was added 1.5 mL of H2SO4. The mixture was heated to reflux and became a homogeneous solution after 1 h. The solution was refluxed for about 16 h, cooled to 22° C. and concentrated to about 10 mL by evaporation. The solution was diluted with 100 mL of water, made basic with 1 N NaOH and extracted with 100 mL of dichloromethane (DCM). The aqueous layer was back-extracted with DCM (4×100 mL). The combined extracts were dried (Na2SO4) and evaporated to give methyl 4-(2-aminoethyl)benzoate as a colorless oil. The material was used directly in the subsequent transformation.
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