| abstract |
The present invention relates to a series of new compounds, their salts and esters and to methods for the preparation of the compounds having the general formula: IN WHICH R1 represents a straight or branched C1-C6 alkyl, alkenyl or alkynyl radical, or a C1-C3 alkyl radical substituted with phenyl, halophenyl, trifluoromethylphenyl, (lower alkoxy)phenyl, or with a 5-membered or 6-membered heterocyclic ring containing not more than two heteroatoms selected from the group consisting of oxygen, sulphur and nitrogen; R2 stands for a phenyl radical, optionally being substituted with halogen, lower alkyl, hydroxy, or lower alkoxy; X stands for oxygen, sulphur or C=O; Y stands for oxygen, sulphur or a methylene radical.n[US3898266A] |