Compounds of formula I are provided where X
1
, X
2
, and X
3
are independently selected from H or hydroxy protecting groups. Such compounds may be used in preparing pharmaceutical compositions and are useful in treating a variety of biological conditions.
提供了公式I的化合物,其中X1、X2和X3分别选自H或羟基保护基团。这些化合物可用于制备药物组合物,并可用于治疗各种
生物状况。