Palladium(II)‐Catalyzed CH Activation/CC Cross‐Coupling Reactions: Versatility and Practicality

Abstract

In the past decade, palladium-catalyzed C-H activation/C-C bond forming reactions have emerged as promising new catalytic transformations; however, development in this field is still at an early stage compared to the state of the art in cross-coupling reactions using aryl and alkyl halides. This Review begins with a brief introduction of four extensively investigated modes of catalysis for forming C-C bonds from C-H bonds: Pd(II)/Pd(0), Pd(II)/Pd(IV), Pd(0)/Pd(II)/Pd(IV) and Pd(0)/ Pd(II) catalysis. More detailed discussion is then directed towards the recent development of Pd(II)-catalyzed coupling of C-H bonds with organometallic reagents through a Pd(II)/Pd(0) catalytic cycle. Despite much progress made to date, improving the versatility and practicality of this new reaction remains a tremendous challenge.

Site-selective C–H arylation of primary aliphatic amines enabled by a catalytic transient directing group

“…Furthermore, the primary amines with a cyclic alkyl group reacted smoothly in this catalytic system (2j and 2k). Although many successful examples for functionalizing unactivated secondary sp 3 C−H bonds have been reported with the installation of a mono-or bidentate directing group on the substrates [5][6][7][8][9][10][11][12][13][14][15] , direct functionalization of these bonds remains a great challenge with carbonyl compounds using a transient directing group 37 and free aliphatic amines 23,30,31 , presumably due to the inherent steric hindrance. In this catalytic system, substrate 1l with cyclic methylene C−H bonds provided the γ-arylated product 2l in 23% yield, while arylation of noncyclic secondary C−H bonds was not realized.…”

Upgrading Lignocellulosic Biomasses: Hydrogenolysis of Platform Derived Molecules Promoted by Heterogeneous Pd-Fe Catalysts

“…Palladium has a lower cost and more abundant reserves than platinum (that is still the most widely used element in catalysis) [92,93]. Homogeneous and heterogeneous palladium-based catalysts have found a potential application in several industrial reactions including hydrogenation, dehydrogenation, hydrogenolysis, reforming, oxidation, coupling reactions, carbonylation/decarbonylation and hydrodesulphurization [94][95][96][97][98][99][100][101][102][103][104][105][106]. With respect to other PGM elements, palladium is characterized by a fundamental electronic configuration unique among transition metals (4d 10 , 5s 0 ) [107] that can be strongly influenced by the coordination environment [108].…”

Crystal structure of 2-phenyl-1,4-benzoquinone, C12H8O2

“…Compounds containing the quinone group have been found to exhibit a wide range of pharmacological properties [2,3] and have also been used as reoxidants for palladium-catalyzed reactions [4,5]. Among them, compounds functionalized at the quinone moiety with arylgroups constitute acommonstructural moiety.…”