Preparation of a derivative of thiophosphoric acid

摘要

The process comprises reaction of O-phenylene diamine of formula (II) with chloroacetic acid to give 2-oxo-1234-tetrahydroquinoxaline of formula (III). This latter is reacted with an oxidising agent to give 2-hydroxyquinolaxine of formula (IV) which is then reacted with OO-diethylchlorothiophosphate 1-P(S)(OCH2CH3)2 in the presence of a base such as sodium hydroxide under solid liq. phase transfer conditions yielding acid of formula (I).