Modular Approach to the Synthesis of Polydentate NHC-Ligand Precursors (Benzimidazolium Salts) Containing Axial Chiral 1,1′-Binaphthyl via Pd-Catalyzed N-Arylation of 1,2-Diaminobenzene

Abstract

A convenient and efficient modular approach to the synthesis of polydentate NHC ligand precursors (benzimidazolium salts) containing axial chiral 1,1′-binaphthyl from 1,2-diaminobenzene and BINOL has been developed. The benzimidazolium salts could be regarded as the potential bidentate, tridentate, and tetradentate NHC ligand precursors.

Chiral Bidentate NHC Ligands Based on the 1,1′‐Binaphthyl Scaffold: Synthesis and Application in Transition‐Metal‐Catalyzed Asymmetric Reactions

“…More recently, our group also reported that chiral Au(I) complexes III‐4 could be used as catalysts for a tandem [3,3] rearrangement and intramolecular hydroamination of propargylic esters, affording the desired products in good yields with high enantioselectivities 47. Furthermore, a polydentate NHC ligand precursor containing an axial chiral 1,1′‐binaphthyl moiety has been reported, though it has not been applied in catalytic asymmetric processes 48…”

Transition metal complexes bearing atropisomeric saturated NHC ligands

“…The implementation of planar chirality to the design of chiral NHC ligands has been scarcely investigated 7–11 . By comparison, NHC ligands containing axes of chirality have received slightly more attention 11–21 . The large majority of these ligands contain a binaphthyl moiety, and the complexes bearing such NHCs were found to be efficient in various reactions such as ruthenium‐catalyzed metathesis and gold‐catalyzed transformations.…”

“…[7][8][9][10][11] By comparison, NHC ligands containing axes of chirality have received slightly more attention. [11][12][13][14][15][16][17][18][19][20][21] The large majority of these ligands contain a binaphthyl moiety, and the complexes bearing such NHCs were found to be efficient in various reactions such as ruthenium-catalyzed metathesis and gold-catalyzed transformations. Recently, we have disclosed a new design of metal-NHC complexes containing an axis of chirality.…”

Organocatalytic Si–CAryl Bond Functionalization-Enabled Atroposelective Synthesis of Axially Chiral Biaryl Siloxanes

“…19 The introduction of aryl thiol (11) and amine ( 12) was also achieved with equal efficiencies. 20,21 Notably, these synthetic modifications have occurred without affecting the stereochemical integrity of the axially chiral scaffold.…”

“…Further synthetic elaboration was viable through iodide 7 , which could undertake palladium-catalyzed cross-coupling reactions to form phosphine oxide 9 and monodentate phosphine 10 used successfully in a variety of metal-catalyzed asymmetric reactions . The introduction of aryl thiol ( 11 ) and amine ( 12 ) was also achieved with equal efficiencies. , Notably, these synthetic modifications have occurred without affecting the stereochemical integrity of the axially chiral scaffold.…”