Pyranoside phosphite–phosphoroamidite ligands for Pd-catalyzed asymmetric allylic alkylation reactions

We have designed and synthesized a new family of readily available phosphite–phosphoroamidite ligands for Pd-catalyzed allylic substitution reactions of several substrates with different steric and electronic properties. These ligands are derived from d-glucosamine and contain several substituents in the biphenyl moieties, with different steric and electronic properties. Systematic variation of the ligand parameters indicates that enantioselectivities are mainly affected by the substituents at the para-positions of the biphenyl moieties. Enantiomeric excesses of up to 89% with high activities were obtained for rac-1,3-diphenyl-3-acetoxyprop-1-ene S1, rac-(E)-ethyl-2,5-dimethyl-3-hex-4-enylcarbonate S2 and rac-3-acetoxycycloheptene S5.

Figure optionsDownload as PowerPoint slide

Methyl-2,3-bis[(3,3′,5,5′-tetra-t-butyl-1,1′-biphenyl-2,2′-diyl)phosphite]-2-amine-4-6-O-benzylidene-2-deoxy-α-d-glucopyranosideC70H97NO9P2[α]D20=-78.4 (c 0.5, CHCl3)Source of chirality: chiral poolAbsolute configuration: (1S,2R,3R,4S,5R)

Methyl-2,3-bis[(3,3′-bis-t-butyl-5,5′-bis-methoxy-1,1′-biphenyl-2,2′-diyl)phosphite]-2-amine-4-6-O-benzylidene-2-deoxy-α-d-glucopyranosideC58H73NO13P2[α]D20=-119.9 (c 0.5, CHCl3)Source of chirality: chiral poolAbsolute configuration: (1S,2R,3R,4S,5R)

Methyl-2,3-bis[(3,3′-bis-trimethylsilyl-1,1′-biphenyl-2,2′-diyl)phosphite]-2-amine-4-6-O-benzylidene-2-deoxy-α-d-glucopyranosideC50H65NO9P2Si4[α]D20=-69.9 (c 0.5, CHCl3)Source of chirality: chiral poolAbsolute configuration: (1S,2R,3R,4S,5R)