Stereoconvergent synthesis of enantiopure (-)-trans-lauthisan. Building kit for medium ring oxacycle construction and contrathermodynamic epimerization at allylic carbon C(8) via “invisible”, E-configurated medium ring olefin
作者:H.M.R Hoffmann、Arndt Brandes
DOI:10.1016/0040-4020(94)00960-3
日期:1995.1
Starting once more from simple, acyclic, functionalized α,α′-chiral, disecondary ethers we have prepared enantiomerically pure (-)-trans-lauthisan (which is thermodynamically less stable than its cis-epimer). During a Pd(0) catalyzed cyclization a strained E-configurated, 8-membered allylic ether (as an η2 palladium complex) is believed to be a reactive intermediate, in which the oxygen of the allylic
从简单的,无环的,官能化的α,α'-手性二仲醚开始,我们制备了对映体纯的(-)-反式-lauthisan(在热力学上比其顺式-epimer不稳定)。在钯(0)催化的环化反应的应变E-可配置,8-元烯丙基醚(作为η 2钯复合物)被认为是反应性的中间体,其中所述烯丙基醚届氧离去基团的状态和contrathermodynamically重新闭合并立体收敛于分离的α,α'-反式构型的中环醚。9元环(参见前面的论文)建议由类似的序列形成。