Novel atropisomeric bisphosphine ligands with a bridge across the 5,5′-position of the biphenyl for asymmetric catalysis

A new type of atropisomeric bisphosphine ligand 2 with a bridge across the 5,5′-position of the biphenyl has been developed. The axial chirality of this type of ligands can be retained by macrocyclic ring strain produced from 5,5′-linkage of the biphenyl even without 6,6′-substituents on the biphenyls. Ligand (R)-2a showed good catalytic activity and enantioselectivity for Rh(I)-catalyzed asymmetric hydrogenation of (Z)-α-acetamidocinnamic acid 11.

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(R)-(−)-2,2′-Bis(diphenylphosphinomethyl)-5,5′-(octamethylenedioxy)-1,1′-biphenyl dioxideC46H46O4P2[α]D25=-34.1 (c 1, CHCl3)Source of chirality: resolution by chiral preparative HPLCAbsolute configuration: (R)

(S)-(+)-2,2′-Bis(diphenylphosphinomethyl)-5,5′-(octamethylenedioxy)-1,1′-biphenyl dioxideC46H46O4P2[α]D25=+33.8 (c 1, CHCl3)Source of chirality: resolution by chiral preparative HPLCAbsolute configuration: (S)

(R)-(−)-2,2′-Bis(diphenylphosphinomethyl)-5,5′-(decamethylenedioxy)-1,1′-biphenyl dioxideC48H50O4P2[α]D25=-37.5 (c 1.1, CHCl3)Source of chirality: resolution by chiral preparative HPLCAbsolute configuration: (R)

(S)-(+)-2,2′-Bis(diphenylphosphinomethyl)-5,5′-(decamethylenedioxy)-1,1′-biphenyl dioxideC48H50O4P2[α]D25=+36.8 (c 1.1, CHCl3)Source of chirality: optical resolution by chiral preparative HPLCAbsolute configuration: (S)

(R)-(−)-2,2′-Bis(diphenylphosphinomethyl)-5,5′-(octamethylenedioxy)-1,1′-biphenylC46H46O2P2[α]D25=-28.6 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)

(S)-(+)-2,2′-Bis(diphenylphosphinomethyl)-5,5′-(octamethylenedioxy)-1,1′-biphenylC46H46O2P2[α]D25=+29.8 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (S)

(S)-(+)-2,2′-Bis(diphenylphosphinomethyl)-5,5′-(decamethylenedioxy)-1,1′-biphenylC48H50O2P2[α]D25=+32.8 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (S)

(R)-(−)-2,2′-Bis(diphenylphosphinomethyl)-5,5′-(decamethylenedioxy)-1,1′-biphenylC48H50O2P2[α]D25=-31.5 (c 1.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (R)