Phospha–Wittig试剂RPPMe 3(R = Mes * 2,4,6- t Bu 3 -C 6 H 2;Mes Ter 2,6-(2,4,6-Me 3 C 6 H 2)-C 6 H 3;Dip Ter 2,6-(2,6-iPr 2 C 6 H 3)-C 6 H 3),可以被认为是膦稳定的次膦酸酯。在这项研究中,我们表明PMe 3可以被NHC或NHO取代。有趣的是,类似次膦的反应性会导致随后的C(sp 2)– NHOs中环外CH 2基团的H活化。该概念进一步扩展到烯丙基加成的NHO,产生了膦取代的烯丙基。
Phospha–Wittig试剂RPPMe 3(R = Mes * 2,4,6- t Bu 3 -C 6 H 2;Mes Ter 2,6-(2,4,6-Me 3 C 6 H 2)-C 6 H 3;Dip Ter 2,6-(2,6-iPr 2 C 6 H 3)-C 6 H 3),可以被认为是膦稳定的次膦酸酯。在这项研究中,我们表明PMe 3可以被NHC或NHO取代。有趣的是,类似次膦的反应性会导致随后的C(sp 2)– NHOs中环外CH 2基团的H活化。该概念进一步扩展到烯丙基加成的NHO,产生了膦取代的烯丙基。
On the Dual Role of N-Heterocyclic Carbenes as Bases and Nucleophiles in Reactions with Organic Halides
作者:Axel Jacobi von Wangelin、Christiane Knappke、Anthony Arduengo, III、Haijun Jiao、Jörg-Martin Neudörfl
DOI:10.1055/s-0031-1289593
日期:2011.12
nucleophilicities, and sterics of N-heterocyclic carbenes have been studied in reactions of imidazolin-2-ylidenes with organic halides. Highly nucleophilic and less basic carbenes cleanly gave alkylideneimidazolines, the deoxy analogues of Breslow-type intermediates. More basic NHCs engaged in unwanted deprotonation or dehydrohalogenation reactions. N-heterocyclic carbenes - enamines - umpolung - imidazoles - nucleophilicity
On new N-heterocyclic carbene derived alkylidene imidazolines
作者:Christiane E. I. Knappke、Jörg M. Neudörfl、Axel Jacobi von Wangelin
DOI:10.1039/b921655c
日期:——
A series of novel 2-alkylidene imidazolines has been synthesized from imidazolium halides and substituted alkyl halides in the presence of base. The resultant exocyclic enediamines have been characterized and their nucleophilicity has been evaluated upon NMR spectroscopic data and substitution reactions.