Patent ID: 7008950

Claim:
A compound of the formula: wherein R 1 and R 2 are each a C 1-6 alkyl or R 1 and R 2 form, taken together with the adjacent carbon atom, a piperidine optionally substituted by 1 to 3 substituents selected from the group consisting of C 1-6 alkyl, C 6-14 aryl and C 7-16 aralkyl; R 3 is a phenyl optionally substituted by 1 to 3 substituents selected from the group consisting of halogen atoms, C 1-6 alkyl, C 1-6 alkoxy, amino, mono-C 1-6 alkylamino and di-C 1-6 alkylamino; R 4 is (i) C 1-6 alkyl substituted by a phenyl or pyridyl, each of which is optionally substituted by 1 to 3 substituents selected from the group consisting of halogen atoms, C 1-6 alkyl, C 1-6 alkoxy, hydroxy, amino, mono-C 1-6 alkylamino, di-C 1-6 alkylamino and carboxy, or (ii) an acyl of the formula: —(C═O)—R 5′ wherein R 5′ is a phenyl or phenyl-C 1-6 alkyl, each of which is optionally substituted by 1 to 3 substituents selected from the group consisting of halogen atoms, C 1-6 alkyl, C 1-6 alkoxy, hydroxy, amino, mono-C 1-6 alkylamino, di-C 1-6 alkylamino and carboxy; X is an oxygen atom; Y is an oxygen atom; and ring A is a benzene ring which is optionally further substituted by 1 to 3 substituents selected from the group consisting of halogen atoms, halogenated or unhalogenated C 1-6 alkyl, halogenated or unhalogenated C 1-6 alkoxy, amino, mono-C 1-6 alkylamino and di-C 1-6 alkylamino, provided that when is a single bond, R 4 is not acyl, and salts thereof.