1. 3-Aminophenylacetic acid (15.5 g, 0.10 mol) was suspended in methanol (150 mL) and the mixture was cooled to 0°C.
2. Thionyl chloride (11.2 mL, 0.15 mol) was added slowly and dropwise with continuous stirring.
3. The reaction mixture gradually changed to a clarified orange solution with continued stirring for 4 hours.
4. Upon completion of the reaction, the solvent was removed by rotary evaporator.
5. The residual solid was dissolved in ethyl acetate (150 mL) and washed with saturated sodium bicarbonate solution (150 mL).
6. The organic phase is separated and washed sequentially with saturated sodium bicarbonate solution (100 mL) and brine, and finally dried over anhydrous sodium sulfate.
7. The desiccant was removed by filtration and the filtrate was concentrated under reduced pressure to give methyl 3-aminophenylacetate as a brown oil (14.1 g, 83% yield). 8. The product was analyzed by 1H NMR.
8. The product was characterized by 1H NMR (500 MHz, CDCl3): δ 7.12 (1H, dd), 6.7-6.6 (3H, m), 3.71 (3H, s), 3.55 (2H, s).
9. Follow-up step: conversion of methyl 3-aminophenylacetate to methyl (3-methylsulfonylamino-phenyl)-acetate.
