Development of new chiral phosphine-salen type ligands and their application in the Cu(I)-catalyzed enantioselective Henry reaction

Chiral phosphine-salen type ligand L4 prepared from (R)-2-(diphenylphosphino)-1,1′-binaphthyl-2′-amine was found to be a fairly effective chiral ligand for Cu(I)-promoted enantioselective Henry reactions of arylaldehydes with nitromethane to give the corresponding adducts in moderate enantioselectivities and moderate to good yields.

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(R)-(+)-2-((2-(Diphenylphosphino)-1,1′-binapthyl-2′-ylimino)methyl)phenolC39H28NOPEe = 100%[α]D20=+224.6 (c 0.45, CHCl3)Source of chirality: optical resolutionAbsolute configuration: (R)

(R)-(+)-2,4-Dichloro-6-((2-(diphenylphosphino)-1,1′-binapthyl-2′-ylimino)methyl)phenolC39H26Cl2NOPEe = 100%[α]D20=+163 (c 0.25, CHCl3)Source of chirality: optical resolutionAbsolute configuration: (R)

(R)-(+)-2-((2-(Diphenylphosphino)-1,1′-binapthyl-2′-ylimino)methyl)-4-methylphenolC40H30NOPEe = 100%[α]D20=+178 (c 0.25, CHCl3)Source of chirality: optical resolutionAbsolute configuration: (R)