Diverse Approaches for Enantioselective C−H Functionalization Reactions Using Group 9 Cp^xM^III Catalysts

Abstract

Transition‐metal‐catalyzed C−H functionalization reactions with Cp*MIII catalysts (M=Co, Rh, Ir) have found a wide variety of applications in organic synthesis. Albeit the intrinsic difficulties in achieving catalytic stereocontrol using these catalysts due to their lack of additional coordination sites for external chiral ligands and the conformational flexibility of the Cp ligand, catalytic enantioselective C−H functionalization reactions using the Group 9 metal triad with Cp‐type ligands have been intensively studied since 2012. In this minireview, the progress in these reactions according to the type of the chiral catalyst used are summarized and discussed. The development of chiral Cpx ligands the metal complexes thereof, artificial metalloenzymes, chiral carboxylate‐assisted enantioselective C−H activations, enantioselective alkylations assisted by chiral carboxylic acids or chiral sulfonates, and chiral transient directing groups are discussed.

Rhodium Catalysts with a Chiral Cyclopentadienyl Ligand Derived from Natural R‐Myrtenal

“…Rhodium catalysts with chiral cyclopentadienyl ligands have recently attracted a lot of attention thanks to their successful application in C-H activation reactions. [1][2][3][4][5][6] The most explored catalysts of this type are the binaphthyl derivatives 1 developed by Cramer et al and You et al, [7][8][9][10][11] the amino acid derivatives 2 developed by Antonchik and Waldmann et al, [12] the streptavidine-docked derivatives 3 developed by Ward and Rovis et al, [13,14] as well as some others [15][16][17][18][19][20] (Scheme 1). A wide application of these catalysts is still somewhat limited by their multistep synthesis involving rather expensive starting materials and reagents.…”

“…Rhodium catalysts with chiral cyclopentadienyl ligands have recently attracted a lot of attention thanks to their successful application in C–H activation reactions . The most explored catalysts of this type are the binaphthyl derivatives 1 developed by Cramer et al and You et al, the amino acid derivatives 2 developed by Antonchik and Waldmann et al, the streptavidine‐docked derivatives 3 developed by Ward and Rovis et al,, as well as some others (Scheme ).…”

Chiral Cyclopentadienyl Ligands: Design, Syntheses, and Applications in Asymmetric Catalysis

“…Some of the most prevalent ones include TADDOL ( 1 ), BOX ( 2 ), BINAP ( 3 ), BINOL ( 4 ), and SALEN ( 5 ) (Figure 1). [3, 4] While these all coordinate to metals through heteroatoms, complementary carbon‐coordinating neutral N‐heterocyclic carbenes (NHC, 6 ) [5] or cyclopentadienyl anions (Cp X , 7 ) [6– 9a] have also been proven as effective chiral ligands for asymmetric metal catalysis.…”

Chiral ligands for palladium-catalyzed asymmetric C–H activation

“…在此基础上, 近年来 但却不限于上述几种手性化合物. 其他手性配体如氮 杂环卡宾 [9] 、单膦或双膦配体 [10] , 以及预制的手性催 化剂, 如手性环戊二烯与过渡金属配合物 [11] , 已有较 全面的相关综述见诸报道, 因此不在本文中加以讨论.…”