Zirconium-Catalyzed Imine Hydrogenation via a Frustrated Lewis Pair Mechanism

Zirconium-based frustrated Lewis pairs (FLPs) are active imine hydrogenation catalysts under mild conditions. Complexes of the type [CpR2ZrOMes][B(C6F5)4] utilize the imine substrate itself as the Lewis base component of the FLP. Catalyst performance is a function of ligand structure; in general more bulky, more electron rich cyclopentadienyl derivatives give the best results. However, Cp* derivatives are not catalytically active, being stable after initial heterolytic cleavage of H2; this allows experimental verification of the competence of the zirconocene–imine pair in FLP-type heterolytic H2 cleavage. Enamines and protected nitriles are also hydrogenated if an additional internal phosphine base is used.

[1]  D. Wass,et al.  Small Molecule Activation by Intermolecular Zr(IV)-Phosphine Frustrated Lewis Pairs. , 2016, Journal of the American Chemical Society.

[2]  G. Erker,et al.  Frustrated Lewis pair chemistry: development and perspectives. , 2015, Angewandte Chemie.

[3]  G. Erker,et al.  Synthetic Endeavors toward Titanium Based Frustrated Lewis Pairs with Controlled Electronic and Steric Properties , 2015 .

[4]  D. Stephan.  Frustrated Lewis pairs: from concept to catalysis. , 2015, Accounts of chemical research.

[5]  D. Wass,et al.  Cooperative Lewis pairs based on late transition metals: activation of small molecules by platinum(0) and B(C6 F5 )3. , 2015, Angewandte Chemie.

[6]  D. Stephan.  Frustrated Lewis Pairs. , 2015, Journal of the American Chemical Society.

[7]  G. Erker,et al.  Formation of unsaturated vicinal Zr(+)/P frustrated Lewis pairs by the unique 1,1-carbozirconation reactions. , 2014, Journal of the American Chemical Society.

[8]  D. Wass,et al.  Transition Metal Frustrated Lewis Pairs , 2013 .

[9]  D. Wass,et al.  Frustrated Lewis pairs beyond the main group: synthesis, reactivity, and small molecule activation with cationic zirconocene-phosphinoaryloxide complexes. , 2011, Journal of the American Chemical Society.

[10]  G. Erker.  Frustrated Lewis pairs: Reactions with dihydrogen and other “small molecules” , 2011 .

[11]  D. Wass,et al.  Frustrated Lewis pairs beyond the main group: cationic zirconocene-phosphinoaryloxide complexes and their application in catalytic dehydrogenation of amine boranes. , 2011, Journal of the American Chemical Society.

[12]  Douglas W Stephan,et al.  Frustrated Lewis pairs: metal-free hydrogen activation and more. , 2010, Angewandte Chemie.

[13]  Preston A. Chase,et al.  Lewis acid-catalyzed hydrogenation: B(C6F5)3-mediated reduction of imines and nitriles with H2. , 2008, Chemical communications.

[14]  Preston A. Chase,et al.  Metal-free catalytic hydrogenation. , 2007, Angewandte Chemie.

[15]  J. Khinast,et al.  Enantioselective Hydrogenations with Chiral Titanocenes , 2005, Molecules.

[16]  D. Stephan,et al.  Reactivity of Decamethylzirconocene Trihydride Anion with Protic Reagents , 2000 .

[17]  S. Buchwald,et al.  Asymmetric Hydrogenation of Unfunctionalized Tetrasubstituted Olefins with a Cationic Zirconocene Catalyst , 1999 .

[18]  L. Paquette,et al.  Catalytic enantioselective hydrogenation of 1,1-disubstituted alkenes with optically active titanocene and zirconocene complexes containing either identical or different ligands , 1995 .

[19]  S. Buchwald,et al.  CATALYTIC ASYMMETRIC HYDROGENATION OF IMINES WITH A CHIRAL TITANOCENE CATALYST : KINETIC AND MECHANISTIC INVESTIGATIONS , 1994 .

[20]  S. Buchwald,et al.  CATALYTIC ASYMMETRIC HYDROGENATION OF IMINES WITH A CHIRAL TITANOCENE CATALYST : SCOPE AND LIMITATIONS , 1994 .

[21]  J. C. Flores,et al.  Dicyclopentadienyl-titanium and -zirconium complexes as catalysts for hydrogenation of olefins , 1993 .

[22]  S. Buchwald,et al.  Synthesis of highly enantiomerically enriched cyclic amines by the catalytic asymmetric hydrogenation of cyclic imines , 1993 .

[23]  S. Buchwald,et al.  Asymmetric titanocene-catalyzed hydrogenation of imines , 1992 .