Antiallergy agents. I. 1,6-dihydro-6-oxo-2-phenylpyrimidine-5-carboxylic acids and esters
The synthesis of some 1,6-dihydro-6-oxo-2-phenylpyrimidine-5-carboxylic acids and esters with potent oral and intravenous antiallergic activity against passive cutaneous anaphylaxis in the rat is described. Requirements for high activity include a free NH group in the pyrimidinone nucleus and a small to medium size ortho alkoxy or alkenyloxy group on the phenyl ring. It is suggested that in the case of the highly active compounds hydrogen bonding occurs between a nitrogen of the pyrimidine ring and the ethereal oxygen. The nature of this bonding and its possible contribution to an optimum configuration for the molecules is discussed.
A series of 1,6-dihydro-6-oxo-2-(ortho-substituted phenyl)pyrimidine-5-carboxylic acid derivatives is provided for use as inhibitors of allergic reactions. The compounds show antiallergy activity by both oral and parenteral routes of administration.