C22-C34 portion (2) of halichondrin B was synthesized from meso-symmetric bis-silyl protected cyclopentenediol (7) in 20 steps and 7% overall yield. This was accomplished through a two-directional synthesis/terminus differentiation strategy that proceeded via achiral, meso-symmetric intermediates for eight steps and employed a Pd(0)-mediated asymmetric double cycloetherification to establish both tetrahydropyran
卤虫草酮B的C22-C34部分(2)是由内对称的双甲
硅烷基保护的环
戊二醇(7)以20个步骤合成的,总收率为7%。这是通过双向合成/末端分化策略完成的,该策略通过非手性,内消旋中间体进行了八步操作,并采用Pd(0)介导的不对称双
环醚化作用来建立两个
四氢吡喃环。[结构:看文字]