Pd(II)-catalyzed and diethylzinc-mediated asymmetric umpolung allylation of aldehydes in the presence of chiral phosphine-Schiff base type ligands

Chiral phosphine-Schiff base type ligand L3 prepared from (R)-(−)-2-(diphenylphosphino)-1,1′-binaphthyl-2′-amine was found to be a fairly effective chiral ligand for the Pd(II)-catalyzed and diethylzinc-mediated enantioselective umpolung allylation of aldehydes to give homoallylic alcohols in good yields, moderate enantioselectivities and high syn diastereoselectivities.

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

(1R,1′S)-(Cyclohex-2-enyl)(phenyl)methanolC13H16OEe = 66%[α]D20=+11 (c 1.0, C6H6)Source of chirality: asymmetric catalysisAbsolute configuration: (1R,1′S)

(1R,1′S)-(2-Chlorophenyl)(cyclohex-2-enyl)methanolC13H16ClOEe = 68%[α]D20=-24 (c 1.6, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (1R,1′S)

(1R,1′S)-(3-Chlorophenyl)(cyclohex-2-enyl)methanolC13H16ClOEe = 66%[α]D20=+7 (c 1.7, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (1R,1′S)

(1R,1′S)-(4-Chlorophenyl)(cyclohex-2-enyl)methanolC13H16ClOEe = 64%[α]D20=+5 (c 1.4, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (1R,1′S)

(1R,1′S)-(Cyclohex-2-enyl)(4-fluorophenyl)methanolC13H16FOEe = 46%[α]D20=+4 (c 1.2, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (1R,1′S)

(1R,1′S)-(Cyclohex-2-enyl)(4-(trifluoromethyl)phenyl)methanolC14H15F3OEe = 67%[α]D20=+1 (c 1.8, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (1R,1′S)

(1R,1′S)-(Cyclohex-2-enyl)(2,4-dichlorophenyl)methanolC13H14Cl2OEe = 62%[α]D20=-22 (c 2.2, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (1R,1′S)

(1R,1′S)-(Cyclohex-2-enyl)(p-tolyl)methanolC14H18OEe = 37%[α]D20=+5 (c 0.5, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (1R,1′S)

(1R,1′S)-(Cyclohex-2-enyl)(naphthalen-1-yl)methanolC17H18OEe = 47%[α]D20=-27 (c 0.8, CHCl3)Source of chirality: asymmetric catalysisAbsolute configuration: (1R,1′S)