This invention relates to a compound of formula I
 wherein
   p is 1 to 3;
   R¹ and R² each are independently hydrogen or an acyl group R⁶CO-, in which R⁶ is C₁₋₆ alkyl, C₃₋₇ cycloalkyl, C₂₋₇ alkenyl, aryl or radical of the formula
    R³ is hydrogen or chloro;
   R⁴ and R⁵ each are independently C₁₋₆ alkyl.
Compounds of formula I are useful for the reversal of multidrug resistance of cancer drugs.
                            本发明涉及一种式 I 的化合物
 其中
p 为 1 至 3;
R¹ 和 R² 各自独立地为氢或酰基 R⁶CO-,其中 R⁶ 是 C₁₋₆ 烷基、C₃₋₇ 环烷基、C₂₋₇ 烯基、芳基或式中的基团
 R³ 是氢或
氯;
R⁴ 和 R⁵ 各自独立地为 C₁₋₆ 烷基。
式 I 的化合物可用于逆转抗癌药物的多药耐药性。