Total Synthesis of (-)-PA-48153C, a Novel Immunosuppressive 2-Pyranone Derivative
作者:Ken Yasui、Yoshinori Tamura、Takuji Nakatani、Kenji Kawada、Mitsuaki Ohtani
DOI:10.1021/jo00128a032
日期:1995.11
(-)-PA-48153C (1), an immunosuppressive agent, was synthesized by starting from (+)-methyl 4,6-O-benzylidene-alpha-D-glucopyranoside (2) and (S)-(+)-methyl 3-hydroxy-2-methylpropionate (3). The key steps in this synthesis relied upon trans-diaxial ring opening of epoxy mesylate 11 in order to introduce the C-5 beta ethyl group, Wittig reaction of aldehyde 15 with a phosphorus ylide derived from phosphonium salt 28 to combine the cyclic segment B and the acyclic segment C, and regio- and stereoselective hydroboration of (Z)-olefin 29 in order to introduce the C-8 alpha hydroxyl group. The absolute stereochemistry of PA-48153C was unambiguously determined to be the same as that of 1.
(-)-PA-48153C(1),一种免疫抑制剂,是从(+)-甲基4,6-O-苄基-a-D-吡喃葡萄糖苷(2)和(S)-(+)-甲基3-羟基-2-甲基丙酸酯(3)开始合成的。该合成的关键步骤依赖于通过反式轴向环开反应将环氧硫酸酯11环打开,以引入C-5β乙基;醛15与从鏻盐28衍生的磷叶立德进行的Wittig反应,以结合环段B与无环段C;以及对(Z)-烯烃29的区域选择性和立体选择性硼氢化反应,以引入C-8α羟基。PA-48153C的绝对构型被明确确定与1相同。