Decomposition of a Phosphine-Free Metathesis Catalyst by Amines and Other Bronsted Bases: Metallacyclobutane Deprotonation as a Major Deactivation Pathway
作者:Benjamin J. Ireland、Bernadette T. Dobigny、Deryn E. Fogg
DOI:10.1021/acscatal.5b00813
日期:2015.8.7
Reactions are described of the second-generation Hoveyda catalyst HII with amines, pyridine, and DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), in the presence and absence of olefin substrates. These nitrogen bases have a profoundly negative impact on metathesis yields, but in most cases, they are innocuous toward the precatalyst. HII adducts were formed by primary and secondary amines (n-butylamine, sec-butylamine
描述了在存在和不存在烯烃底物的情况下,第二代Hoveyda催化剂HII与胺,吡啶和DBU(1,8-二氮杂双环[5.4.0] undec-7-ene)的反应。这些氮碱对复分解产率具有严重的负面影响,但在大多数情况下,它们对前催化剂无害。HII加合物是在室温下由伯胺和仲胺(正丁胺,仲丁胺,苄胺,吡咯烷,吗啉),吡啶和DBU形成的。NEt 3甚至在60°C时都没有明显的反应。在室温下进行更长的反应时,未受干扰的伯胺会从HII中提取出亚苄基配体。含10当量的NH 2 nBu,此过程在12小时内完成,得到NH n Bu(CH 2 Ar)(Ar = o -C 6 H 4 -O i Pr)和[RuCl(H 2 IMes)(NH 2 n Bu)4 ] Cl 。对于苄胺,亚苄基提取在室温下进行了数天。对于仲丁胺,仲胺,NEt 3,吡啶或DBU,未观察到这样的反应。然而,所有这些碱都强烈抑制了HII对苯乙烯的