Process for the synthesis of pemetrexed disodium salt

摘要

The present invention relates to a novel process for the preparation of pemetrexed diethyl ester 2; by purifying the mixture obtainable by reacting compounds 1 and 1a in the presence of a chemical agent capable of promoting the formation of a peptide bond in an aprotic organic solvent; characterized in that the mixture is subjected to the following steps:a) washing with a basic aqueous solution;b) concentration of the organic phase;c) addition of a polar organic solvent and/or a mixture of polar organic solvents;d) precipitation of the pemetrexed diethyl ester 2.