Synthetic Studies of Halichondrin B, an Antitumor Polyether Macrolide Isolated from a Marine Sponge. 7. Synthesis of Two C27-C36 Units via Construction of the F Ring and Completely Stereoselective C-Glycosylation Using Mixed Lewis Acids.
作者:Kiyoshi HORITA、Youji SAKURAI、Masaaki NAGASAWA、Osamu YONEMITSU
DOI:10.1248/cpb.45.1558
日期:——
Two C27-C36 units of halichondrin B were synthesized starting from a C31-C34 alcohol, which was easily available from dimethyl L-tartrate, via construction of the F ring, methylation at the C31 position and C-glycosylation. These crucial reactions proceeded completely stereoselectively, and in particular the stereoselective C-glycosylation with allyltrimethylsilane took place only in the presence of both of two Lewis acids, boron trifluoride etherate and trimethylsilyl triflate.
从容易获得的二甲基L-酒石酸盐出发,合成了两个C27-C36单元的海绵素B,这一过程通过构建F环、在C31位进行甲基化和C-糖苷化实现。这些关键反应完全具有立体选择性,尤其是与烯丙基三甲基硅烷的立体选择性C-糖苷化仅在两种路易斯酸——三氟化硼醚合物和三甲基硅基三氟甲磺酸盐的共同存在下进行。