A New Class of C₂‐Symmetric Chiral Cyclopentadienyl Ligand Derived from Ferrocene Scaffold: Design, Synthesis and Application

Abstract

An ew class of C 2-symmetric, chiral cyclopentadienyl ligand based on planar chiral ferrocene backbone was developed. As eries of its corresponding rhodium(I), iridium(I), and ruthenium(II) complexes were prepared as well. In addition, the rhodium(I) complexes were evaluated in the asymmetricc atalytic intramolecular amidoarylation of olefin-tethered benzamides via CÀHa ctivation. Figure 1. Cp ligands studied in asymmetric CÀHa ctivationreactions.

Applications of Chiral Cyclopentadienyl (Cpx) Metal Complexes in Asymmetric Catalysis

“…In the future it is likely that further attempts to make chiral Cp x ligands more accessible will be made enabling enantioselective transformations to be further investigated. While writing this manuscript two new reports describing another class of chiral Cp x ligands [73] and a new iridium catalyst for an enantioselective hydrogenation were reported. [74] In this minireview, the development and application of chiral Cp x ligands in asymmetric catalysis has been summarised with the goal to enable rapid entry into the field.…”

“…In the future it is likely that further attempts to make chiral Cp x ligands more accessible will be made enabling enantioselective transformations to be further investigated. While writing this manuscript two new reports describing another class of chiral Cp x ligands [ 73 ] and a new iridium catalyst for an enantioselective hydrogenation were reported. [ 74 ]…”

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.…”

Chiral Bicyclo[2.2.2]octane‐Fused CpRh Complexes: Synthesis and Potential Use in Asymmetric C−H Activation

“…[6] So far, the use of CpM catalysts derived from chiral Cp ligands has become one of the most general and effective methods to realize asymmetric C À H activation. [3a] Since the pioneering work by Cramer, [7] diverse chiral Cp ligands have been revealed, including cyclohexane-fused Cp I, [7][8] binaphthyl Cp II, [9,10] spirobiindanyl Cp III, [11,12] biphenyl Cp IV, [13] piperidine-fused Cp V, [14,15] cyclopentane-fused Cp VI, [16] and ferrocenyl Cp VII [17] (Figure 1). Besides, optically pure planar chiral CpM catalysts bearing achiral Cp ligands obtained by chiral resolution were also disclosed.…”

“…Later, from 1986 to 1991, some other relevant ligands were synthesized by Halterman,[19a,c,e,f,h] Vollhardt, [19e,f,h] Paquette, [19d,g] and Erker [19b] et al However, surprisingly, during the past two decades these Cp ligands have not aroused much interest of chemists and been rarely studied. Driven by our continuous interest in exploring new chiral Cp catalysts [17] and new reactions [6, 12a,b, 20] for asymmetric C À H activation, recently we dedicated ourselves to developing chiral bridged-ring-based Cp catalysts for highly enantioselective CÀH activation. As a result, we present herein the first synthesis and application of chiral bridged-ring-based CpRh catalyst in asymmetric CÀH activation.…”