1: NaOH / methanol; H2O / 1 h / 65 °C 2: 1.) triethylamine, ethylchloroformate / 1.)DMF, 0 deg C, 30 min, 2.) room temp. overnight View Scheme

chloroformic acid ethyl ester; triethylamine 1.)DMF, 0 deg C, 30 min, 2.) room temp. overnight; Yield given. Multistep reaction;