| 摘要 |
<p>Compounds are disclosed having the general formula: (I) wherein R1 is H, C1-4 alkyl, or benzyl; R2 is H or C1-4 alkyl; or is a 5-, 6- or 7- membered saturated heterocyclic group; R3 is H, C1-4 alkyl or C1-4 acyl; R4 is an aromatic group; R5 and R6 are each H or C1-4 alkyl; X is - CH2 or -O-; and the dotted line is a single or double bond; also their pharmaceutically acceptable salts. Methods of preparation are also disclosed.</p> |
