PROCESS FOR PREPARING ACTIVE ESTERS

摘要

The present invention relates to a method for the preparation of active ester, characterized by subjecting to a reaction a mixture of a carboxylic acid, which is a starting material, reagent which forms active ester and a base or a starting material carboxylic acid. <??>The present invention provides an active ester useful as an intermediate of pharmaceutical drugs etc. in high yield using an inexpensive reagent, in one-pot reaction, without causing isomerization, regardless of the structure of starting material carboxylic acid.