1: CH2Cl2 / 25 °C 2: 1.) aq. sodium hydroxide, 2.) hydrochloric acid (pH 2) / 1.) 25 deg C, 48 h, 2.) 0 --> 25 deg C, 2 h; further 1-(2-pyridyl)-2-ethoxycarbonylpyridinium salts View Scheme

ethanol

ethanol Heating;

Heating;