Purification of 1,2-dihydro-6-alkyl-2-oxo-5-(pyridinyl)-nicotinonitriles

摘要

The present invention comprises a process for preparing essentially pure 1,2-dihydro-6-alkyl-2-oxo-5-(pyridinyl)-nicotinonitriles from a crude reaction mixture containing the corresponding amide as an impurity. By "essentially pure" is meant a level of purity acceptable for orally administered pharmaceutical products, usually less than 0.1% of any single impurity. At least a stoichiometric amount of an acylating agent is reacted with the crude reaction mixture, and thereafter recovering essentially pure 1,2-dihydro-6-alkyl-2-oxo 5-(pyridinyl)-nicotinonitrile.