PROCESS OR PRODUCING 1,6,7,8-TETRAHYDRO-PYRIDO-SQUARE BRACKET-1,2-A-SQUARE BRACKET CLOSED-PYRIMIDINE-3-CARBOXYLIC ACID DERIVATIVES

摘要

Pyrimido 1,2-a heterocyclic carboxylic acids of formula (I) and their optical isomers are new (where m is 0,1 2 or 3; n is 0,1,2 or 3; R is 1-6C alkyl; R1 is H or 1-6C alkyl; X is O or S). (I) have a beneficial effect on the blood circulation and oxygenation of tissues. They are also used as intermediates for other drugs. A typical cpd., 1,6-dimethyl-4-oxo-1,6,7,8-tetrahydro-4H-pyrido 1,2-a pyrimidine-- 3-carboxylic acid, was prepd. by treating 3-carboxy-1,6-dimethyl-4-oxo-6,7,8,9-tetrahydro-4H-pyrido 1,2-a p- yrimidinium methosulphate with KHCO3 in water.