Stereochemistry of C-6 Nucleophilic Displacements on 1,1-Difluorocyclopropyldibenzosuberanyl Substrates. An Improved Synthesis of Multidrug Resistance Modulator LY335979 Trihydrochloride
作者:Charles J. Barnett、Bret Huff、Michael E. Kobierski、Michael Letourneau、Thomas M. Wilson
DOI:10.1021/jo049051v
日期:2004.10.1
of piperazine products, with the syn:anti product ratio increased by solvent effects. Reaction of 6 with pyridine and pyrazine, on the other hand, gave anti-pyridinium and pyrazinium salts, respectively, apparently via equilibration of initially formed syn products. Reduction of pyrazinium salt 11 with lithium borohydride/TFA provided anti-2 unaccompanied by its syn isomer. A practical and expeditious
对1,1-二氟环丙基二苯并异戊烷醇4及其活化的溴化物衍生物6的置换化学的研究已导致对抗2的改进方法,抗2是LY335979 3HCl(1)的关键前体。任一的溴化顺式-4或抗4得到的反面向6,表示热力学控制产品的立体化学通过稳定的1,1- difluorohomotropylium离子中间体。6与哌嗪的反应不可逆地进行,以提供哌嗪产物的异构体混合物,其中顺式:反式产物的比例因溶剂作用而增加。反应6另一方面,明显地通过平衡最初形成的合成产物,用吡啶和吡嗪与吡啶和吡嗪分别得到抗吡啶鎓盐和吡嗪鎓盐。用硼氢化锂/ TFA还原吡嗪鎓盐11提供了抗2,但其同分异构体没有伴随。从这些新结果中得出了一种实用且快速的方法来处理1。