Rearrangement Approaches to Cyclic Skeletons. XIII. Total Synthesis of Triquinane Sesquiterpenes, (±)-Modhephene, and (±)-Isocomene, on the Basis of Formal Substitution at Both Bridgeheads of a Bicyclo[2.2.2]oct-5-en-2-one
作者:Tadao Uyehara、Tomohiro Murayama、Katsunori Sakai、Kayoko Onda、Masako Ueno、Toshio Sato
DOI:10.1246/bcsj.71.231
日期:1998.1
corresponding α,β-unsaturated ketone, and then treated with R2Li or DIBAL-H (R2 = H). Acid treatment of the resulting allyl alcohols gave the bicyclo[2.2.2]oct-5-en-2-one having substituents R, R1, and R2 at the C-1, 4, and 5 positions, respectively. This procedure was successfully applied to a formal total synthesis of (±)-modhephene, a propellane-type triquinane sesquiterpene, and that of (±)-isocomene
1,4-二甲氧基双环[2.2.2]oct-5-en-2-one和R1MgX反应,然后用对甲苯磺酸在苯中处理,得到5-甲氧基双环[3.2.1]oct-6- en-2-one 在 C-1 桥头具有取代基 (R1)。该酮被转化为5-甲氧基双环[3.2.1]oct-3-en-2-one。通过用 Li[CuR2] 处理,在共轭酮的 C-4 位置引入了第二个桥头取代基 (R)。产物转化为相应的α,β-不饱和酮,然后用R2Li或DIBAL-H(R2=H)处理。对所得烯丙醇进行酸处理,得到分别在 C-1、4 和 5 位具有取代基 R、R1 和 R2 的双环 [2.2.2]oct-5-en-2-one。该程序成功地应用于 (±)-modhephene 的正式全合成,一种推进式三喹烷倍半萜,