| 摘要 |
A compound of the formula (I), wherein R1 and R2 independently of one another are hydrogen, C1-C22alkyl, -Ο·, -OH, -CH2CN, C1-C18alkoxy, C2-C18alkoxy substituted by -OH; C5-C12cycloalkoxy, C3-C6alkenyl, C3-C6alkenyloxy, C7-C9phenylalkyl unsubstituted or substituted on the phenyl by 1, 2 or 3 C1-C4alkyl; or C1-C8acyl; and R3 and R4 independently of one another are C1-C22alkyl or a group of the formula (la), wherein R0 has one of the meanings of R1 and R2. |
