Stereochemistry of Pd<sup>II</sup>-Catalyzed THF Ring Formation of ε-Hydroxy Allylic Alcohols and Synthesis of 2,3,5-Trisubstituted and 2,3,4,5-Tetrasubstituted Tetrahydrofurans
作者:Yuki Murata、Jun’ichi Uenishi
DOI:10.1021/acs.joc.6b01154
日期:2016.9.2
and 2,3,4,5-tetrasubstituted tetrahydrofurans is described. Oxypalladation of a chiral ε-hydroxy allylic alcohol provides a 5-alkenyltetrahydrofuran ring in excellent yields via a 5-exo-trigonal process. Nine substrates including six secondary allylic alcohols and three primary allylic alcohols with or without an additional secondary hydroxy substituent at the γ-position have been examined. Their structures
描述了2,3,5-三取代的和2,3,4,5-四取代的四氢呋喃的Pd II催化的环形成。手性ε-羟基烯丙醇的羟palpalladation提供了一个5烯基四氢呋喃环以优异的产量通过5 -exo-triagonal过程。已经研究了九种底物,包括六种仲烯丙基醇和三种伯烯丙基醇,在γ位上有或没有额外的仲羟基取代基。它们的结构受2,2,4,4-四异丙基-1,3,5,2,4-三氧二硅氧烷环的限制。通过化学转化确定所得四氢呋喃产物的立体化学。根据立体化学结果讨论了反应机理。在涉及手性烯丙基醇或亲核醇的步骤涉及面部选择用于形成烯烃-钯II -π-复杂,顺-oxypalladation,以及顺式β-消除机构帐户用于反应的观察立体化学。