Efficient Access to Substituted Silafluorenes by Nickel-Catalyzed Reactions of Biphenylenes with Et<sub>2</sub>SiH<sub>2</sub>
作者:Jens Michael Breunig、Puneet Gupta、Animesh Das、Samat Tussupbayev、Martin Diefenbach、Michael Bolte、Matthias Wagner、Max C. Holthausen、Hans-Wolfram Lerner
DOI:10.1002/asia.201402599
日期:2014.11
[Ni(PPhMe2)4]‐catalyzed reaction of Et2SiH2 and 1‐methylbiphenylene. By contrast, no selectivity could be found in the Ni‐catalyzed reaction between Et2SiH2 and the biphenylene derivative that bears tBu substituents in the 2‐ and 7‐positions. Therefore, two pairs of isomers of tBu‐substituted silafluorenes and of the related diethylhydrosilylbiphenyls were formed in this reaction. However, a subsequent
在[Ni(PPhMe 2)4 ]存在下,联苯(1)与Et 2 SiH 2的反应导致形成2-二乙基氢甲硅烷基联苯[ 2(Et 2 HSi)]和9,9,-二乙基的混合物‐9‐硅芴(3)。分离出37.5%的Silafluorene 3和36.9%的产率的2(Et 2 HSi)。通过DFT计算阐明了潜在的反应机理。由[Ni(PPhMe 2)4 ]催化的Et 2 SiH反应选择性地获得了4-甲基-9,9-二乙基-9-硅芴(7)2和1-甲基联苯。相比之下,在Et 2 SiH 2和在2位和7位带有t Bu取代基的联苯衍生物之间的Ni催化反应中,没有发现选择性。因此,在该反应中形成了t Bu-取代的硅芴和相关的二乙基氢甲硅烷基联苯的两对异构体。但是,随后用威尔金森氏催化剂将二乙基氢甲硅烷基联苯脱氢,得到了2,7-二叔丁基-9,9-二乙基-9-硅芴(8)和3,6-二叔丁基9的混合物, 9-二乙基-9-硅芴(9)。硅芴8和9