Development of diverse adjustable axially chiral biphenyl ligands and catalysts

Abstract

Summary: Development of highly efficient and practical chiral ligands and catalysts is an eternal theme in asymmetric synthesis. Here, we report the design, synthesis, and evaluation of a new kind of adjustable axially chiral biphenyl ligands and catalysts, in which six model reactions including asymmetric additions of diethylzinc or alkynes to aldehydes in the presence of axially chiral [1,1′-biphenyl]-2,2′-diol ligands, palladium-catalyzed asymmetric cycloadditions in the presence of phosphoramidite ligands, and chiral phosphoric acid-catalyzed asymmetric synthesis of 1,1′-spirobiindane-7,7′-diol derivative and [4 + 3] cyclization were attempted. The results showed that variation of 2,2′-substituent groups could provide different types of ligands and catalysts, and adjustment of substituent groups at the 3,3′, 5,5′, 6,6′-positions could make ligands and catalysts more efficient in the asymmetric catalytic synthesis. Therefore, our present research should provide a new and useful strategy for development of diverse axially chiral ligands and catalysts.

Keywords

• Organic synthesis
• Stereochemistry
• Organic chemistry methods