Synthesis of Methyl 2-Pyrone-4-carboxylate

Abstract

As a consequence of our continuing interests in the cycloaddition reaction of the 2-pyrone derivatives,¹ we have required methyl esters of four 2-pyronecarboxylic acid isomers. Whereas 2-pyrone-3-, 5-, and 6-carboxylic acids or their esters²⁾ had been already synthesized, only 2-pyrone-4- carboxylic acid (la) is still unknown, except its 6-methyl derivative.³

In this communication we disclose the preparation of 1 by Wittig reaction between 2, 2-disubstituted acetaldehyde (2) and dimethyl 2-triphenylphosphoranediylidenesuccinate (3), followed by acid-catalyzed cyclization into the pyrone ring.