aldol reaction of 8 with 9 gives the aldol product 7 in high yield and excellent diastereoselectivity, due to double stereodifferentiation. This compound was used for an efficient synthesis of the natural product auripyrone B 2 in only 20 steps and 8% overall yield from 14 using a late-stage spiroketalization onto a stable hemiketal as the final key step.
非羟醛羟醛-
铜酸酯开环通过八个步骤从环氧醚14生成聚
丙酸酯11作为单一非对映异构体。由于双立体分化,8与9的高度立体选择性羟醛反应以高产率和优异的非对映选择性产生羟醛产物7 。该化合物用于有效合成
天然产物 auripyrone B 2,仅需要 20 个步骤,并且使用后期螺
缩酮化为稳定的半
缩酮作为最后的关键步骤,14的总产率为 8%。