Coinage Metal Complexes of Chiral N‐Heterocyclic Carbene Ligands: Syntheses and Applications in Asymmetric Catalysis

Abstract

Chiral N‐heterocyclic carbenes (NHCs) have become ligands of choice due to their remarkable catalytic activity in organic transformation reactions. Combining the chiral NHC ligand family and coinage metals became a productive area of research. The organometallic chemistry of coinage metals with the chiral N‐heterocyclic carbene (NHC) ligands is reviewed, with a special emphasis on the synthesis, characterization and possible applications obtained. Significant sections are devoted to the various recently developed coinage metal‐chiral NHC complexes and a detailed comparison of their activities which aims to rationalize the structure–activity relationships. Various methods of preparations of coinage metal‐chiral NHC complexes along with some typical examples of reactivity and mechanisms are covered. Cu‐chiral NHC complexes involved in conjugated additions, allylic substitutions, boration of alkenes, hydrosilylation of ketones and formation of alkenes are covered, along with some remarkable examples and reactivity of Ag‐chiral NHC complexes. Finally, applications of Au‐chiral NHC complexes in the asymmetric cyclization of ester‐functionalized 1,6‐enynes, 1,6‐enyneamines and substituted propargyloxymethanes are also reviewed.

Au(III) catalyzes the cross-coupling between activated methylenes and alkene derivatives

“…Gold catalysis is one of the most captivating topics in Organic Chemistry [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In recent years, particular attention has been devoted to gold catalyzed CAH bond activations as a strategic tool for the formation of new CAC bonds.…”

Metal‐Metal Interactions in Bi‐, Tri‐ and Multinuclear Fe, Ru and Os N‐Heterocyclic Carbene Complexes and their Catalytic Applications

“…Many reviews, prospectives, highlights and comments covering important aspects of transition metal NHC complexes focusing on one particular aspect such as either olefin metathesis, C−C bond formation, reactivity or biological applications, while several others dealt with the organometallic chemistry of carbene complexes featuring specific concepts have been published. These reviews include catalytic hydrogenation reactions of ruthenium(II)−NHC complexes, [17] Fischer type carbene complexes and their multimetal carbene counterparts, [18] electronic properties of NHC complexes, [19] high oxidation state complexes of NHC ligands, [20] coinage metal chiral NHC complexes, [21] organometallic chemistry of 1,2,3‐triazole derived NHC ligands, [22] gold(I) NHC complexes, [23] F‐block NHC complexes, [24] abnormal mesoionic and remote NHC complexes, [25] so on.…”

Reversal of Enantioselectivity in the Conjugate Addition Reaction of Cyclic Enones with the CuOTf/Azolium Catalytic System

“…In previous studies, we showed that the hydroxyamide-functionalized NHC•AgI (NHC = N-heterocyclic carbene) complex 1b , derived from leucine, was a versatile chiral ligand precursor for dual enantioselective control in the CuOTf-catalyzed ACA reaction of a cyclic enone with Et 2 Zn [ 15 , 16 ]. The NHC•AgI complex 1 can be easily synthesized by the well-known Ag 2 O method [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. Thus, the treatment of azolium salt (NHC•HI, 4 ) with a 0.5 equiv.…”