Transition-Metal-Catalyzed Hydrogen-Transfer Annulations: Access to Heterocyclic Scaffolds

2015 ◽  
Vol 54 (38) ◽  
pp. 11022-11034 ◽  
Author(s):  
Avanashiappan Nandakumar ◽  
Siba Prasad Midya ◽  
Vinod Gokulkrishna Landge ◽  
Ekambaram Balaraman
Keyword(s):  
Transition Metal ◽  
Hydrogen Transfer ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

scholarly journals A combination of experimental and computational methods to study the reactions during a Lignin-First approach

2020 ◽  
Vol 92 (4) ◽  
pp. 631-639
Author(s):  
Ivan Kumaniaev ◽  
Elena Subbotina ◽  
Maxim V. Galkin ◽  
Pemikar Srifa ◽  
Susanna Monti ◽  
...  
Keyword(s):  
Transition Metal ◽  
Hydrogen Transfer ◽  
Transfer Hydrogenation ◽  
Metal Catalyst ◽  
Main Role ◽  
One Pot ◽  
Transition Metal Catalyst ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

AbstractCurrent pulping technologies only valorize the cellulosic fiber giving total yields from biomass below 50 %. Catalytic fractionation enables valorization of both cellulose, lignin, and, optionally, also the hemicellulose. The process consists of two operations occurring in one pot: (1) solvolysis to separate lignin and hemicellulose from cellulose, and (2) transition metal catalyzed reactions to depolymerize lignin and to stabilized monophenolic products. In this article, new insights into the roles of the solvolysis step as well as the operation of the transition metal catalyst are given. By separating the solvolysis and transition metal catalyzed hydrogen transfer reactions in space and time by applying a flow-through set-up, we have been able to study the solvolysis and transition metal catalyzed reactions separately. Interestingly, the solvolysis generates a high amount of monophenolic compounds by pealing off the end groups from the lignin polymer and the main role of the transition metal catalyst is to stabilize these monomers by transfer hydrogenation/hydrogenolysis reactions. The experimental data from the transition metal catalyzed transfer hydrogenation/hydrogenolysis reactions was supported by molecular dynamics simulations using ReaXFF.

Mechanistic aspects of transition metal-catalyzed hydrogen transfer reactions

2006 ◽  
Vol 35 (3) ◽  
pp. 237 ◽  
Author(s):  
Joseph S. M. Samec ◽  
Jan-E. Bäckvall ◽  
Pher G. Andersson ◽  
Peter Brandt
Keyword(s):  
Transition Metal ◽  
Hydrogen Transfer ◽  
Transfer Reactions ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed ◽  
Hydrogen Transfer Reactions

ChemInform Abstract: Transition-Metal-Catalyzed Hydrogen-Transfer Annulations: Access to Heterocyclic Scaffolds

ChemInform ◽  
2015 ◽  
Vol 46 (45) ◽  
pp. no-no
Author(s):  
Avanashiappan Nandakumar ◽  
Siba Prasad Midya ◽  
Vinod Gokulkrishna Landge ◽  
Ekambaram Balaraman
Keyword(s):  
Transition Metal ◽  
Hydrogen Transfer ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

Mechanistic Aspects of Transition Metal-Catalyzed Hydrogen Transfer Reactions

ChemInform ◽  
2006 ◽  
Vol 37 (23) ◽  
Author(s):  
Joseph S. M. Samec ◽  
Jan-E. Baeckvall ◽  
Pher G. Andersson ◽  
Peter Brandt
Keyword(s):  
Transition Metal ◽  
Hydrogen Transfer ◽  
Transfer Reactions ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed ◽  
Hydrogen Transfer Reactions

Chelation-assisted transition metal-catalysed C–H chalcogenylations

2020 ◽  
Vol 7 (8) ◽  
pp. 1022-1060 ◽  
Author(s):  
Wenbo Ma ◽  
Nikolaos Kaplaneris ◽  
Xinyue Fang ◽  
Linghui Gu ◽  
Ruhuai Mei ◽  
...  
Keyword(s):  
Transition Metal ◽  
Recent Advances ◽  
Site Selectivity ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

This review summarizes recent advances in C–S and C–Se formations via transition metal-catalyzed C–H functionalization utilizing directing groups to control the site-selectivity.

Monodentate Trialkylphosphines: Privileged Ligands in Metal-catalyzed Crosscoupling Reactions

2020 ◽  
Vol 24 (3) ◽  
pp. 231-264 ◽  
Author(s):  
Kevin H. Shaughnessy
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Aryl Bromides ◽  
Wide Range ◽  
Sterically Demanding ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Phosphines are widely used ligands in transition metal-catalyzed reactions. Arylphosphines, such as triphenylphosphine, were among the first phosphines to show broad utility in catalysis. Beginning in the late 1990s, sterically demanding and electronrich trialkylphosphines began to receive attention as supporting ligands. These ligands were found to be particularly effective at promoting oxidative addition in cross-coupling of aryl halides. With electron-rich, sterically demanding ligands, such as tri-tertbutylphosphine, coupling of aryl bromides could be achieved at room temperature. More importantly, the less reactive, but more broadly available, aryl chlorides became accessible substrates. Tri-tert-butylphosphine has become a privileged ligand that has found application in a wide range of late transition-metal catalyzed coupling reactions. This success has led to the use of numerous monodentate trialkylphosphines in cross-coupling reactions. This review will discuss the general properties and features of monodentate trialkylphosphines and their application in cross-coupling reactions of C–X and C–H bonds.

Transition-Metal-Catalyzed Oxidative and Decarboxylative Acylations through sp2 C-H Bond Activation

2015 ◽  
Vol 20 (5) ◽  
pp. 471-511 ◽  
Author(s):  
Satyasheel Sharma ◽  
Neeraj Kumar Mishra ◽  
Youngmi Shin ◽  
In Su Kim
Keyword(s):  
Transition Metal ◽  
Bond Activation ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

Chemistry of Unsymmetrical C1-Substituted Oxabenzonorbornadienes

2021 ◽  
Vol 17 ◽  
Author(s):  
Austin Pounder ◽  
Angel Ho ◽  
Matthew Macleod ◽  
William Tam
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Substituent Effects ◽  
Face Selectivity ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Synthetic Intermediate

: Oxabenzonorbornadiene (OBD) is a useful synthetic intermediate which can be readily activated by transition metal complexes with great face selectivity due to its dual-faced nature and intrinsic angle strain on the alkene. To date, the understanding of transition-metal catalyzed reactions of OBD itself has burgeoned; however, this has not been the case for unsymmetrical OBDs. Throughout the development of these reactions, the nature of C1-substituent has proven to have a profound effect on both the reactivity and selectivity of the outcome of the reaction. Upon substitution, different modes of reactivity arise, contributing to the possibility of multiple stereo-, regio-, and in extreme cases, constitutional isomers which can provide unique means of constructing a variety of synthetically useful cyclic frameworks. To maximize selectivity, an understanding of bridgehead substituent effects is crucial. To that end, this review outlines hitherto reported examples of bridgehead substituent effects on the chemistry of unsymmetrical C1-substituted OBDs.

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