Studies Directed toward the Total Synthesis of Cerorubenic Acid-III. 5. A Radical Cyclization Route Leading to the Methyl Ester of the Natural Isomer<sup>1</sup>
作者:Leo A. Paquette、Brian P. Dyck
DOI:10.1021/ja980691n
日期:1998.6.1
The first total synthesis of cerorubenic acid-III methyl ester is detailed. Enantiopure 4, obtained by anionic oxy-Cope rearrangement of 3, was transformed via diol 11 into lactol 20. Following proper establishment of both side chains as in 25, a 6-exo radical cyclization was employed to set the configuration of the remaining stereogenic centers. This very useful process set the stage for construction
详述了蜡红烯酸-III甲酯的首次全合成。Enantiopure 4,通过阴离子 oxy-Cope 重排 3 获得,通过二醇 11 转化为乳醇 20。在 25 中正确建立两个侧链后,采用 6-exo 自由基环化来设置剩余立体中心的构型. 这个非常有用的过程为构建悬垂侧链奠定了基础。从 3-甲基环己烯酮到 2 的完整路线需要 30 个步骤(总产率为 0.3%),证实了最初的复杂结构分配,并确定了天然开罗酮的绝对构型。