Acylation by acid chloride or acid anhydride and DCC methods were involved in the preparaion to avoid the tedious operation of isolation, because the pure compound could be prepared by the routine crystallization.

• 为避免各步反应产物不易分离带来的麻烦,分别用酰氯法、酸酐法和DCC法合成这些化合物,用常规结晶方法即可精制产物。