Reduction of indole-2-carboxylic acids to indoline-2-carboxylic acids with lithium, sodium, or potassium in ammonia

摘要

Disclosed herein is an efficient and selective reduction of indole-2- carboxylic acids or esters to indoline-2-carboxylic acids using lithium, sodium, or potassium in liquid ammonia. The preferred process uses lithium in liquid ammonia with small amounts of a weak proton donor such as aniline added to the reaction mixture.