| 摘要 |
<p>This invention relates to compounds having the following structure: wherein Y is O, X is O, bond a is absent and bond ß is present, or Y is H, X is CH, bond a is present, and bond ß is absent; atom Z is a carbon and bonds ?, d and ? are present, or atom Z is a nitrogen and bonds ?, d and ? are absent, or atom Z is a nitrogen and bonds ? and d are present and ? is absent. R1, R2, R3, R4, R5, and R6 are various substituents as described in the specification.</p> |
