Preparation of a polymer-supported chiral 1,2-diamine and its application to the asymmetric hydrogenation of aromatic ketones

Polymer-supported chiral 1,2-diamines were prepared by two methods including (1) chemical modification of a Merrifield-type resin with a chiral 1,2-diamine and (2) polymerization of a 1,2-diamine monomer. The polymeric complex formed by the polymer-supported 1,2-diamine and RuCl2-BINAP was used for the asymmetric hydrogenation of aromatic ketones to afford the corresponding secondary alcohols in quantitative yields with high enantioselectivities up to 99% ee in the asymmetric hydrogenation. The polymeric catalyst could be reused many times without any loss of activity or enantioselectivity.

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(R,R)-N,N′-DiBoc-1,2-bis(p-hydroxyphenyl)-1,2-diaminoethaneC24H23N2O6[α]D = −3.8 (c 1.07, CH3OH)Absolute configuration: (1R,2R)Source of chirality: optical resolution

(R,R)-N,N′-DiBoc-1-(p-hydroxyphenyl)-2-(p-benzyloxyphenyl)-1,2-diaminoethaneC33H40N2O6[α]D = −15.0 (c 1.00, CHCl3)Absolute configuration: (1R,2R)Source of chirality: (R,R)-N,N′-diboc-1,2-bis(p-hydroxyphenyl)-1,2-diaminoethane

(R,R)-N,N′-DiBoc-1-(p-hydroxyphenyl)-2-(p-(p-vinylbenzyloxy)phenyl)-1,2-diaminoethaneC33H40N2O6[α]D = −15.7 (c 1.00, CHCl3)Absolute configuration: (1R,2R)Source of chirality: (R,R)-N,N′-diboc-1,2-bis(p-hydroxyphenyl)-1,2-diaminoethanes

(R,R)-N,N′-DiBoc-1-(p-(p-benzyloxy)phenyl)-2-(p-(p-vinylphenylbutyloxy)-phenyl)-1,2-diaminoethaneC43H52N2O6[α]D = −1.9 (c 1.00, CHCl3)Absolute configuration: (1R,2R)Source of chirality: (R,R)-N,N′-diboc-1,2-bis(p-hydroxyphenyl)-1,2-diaminoethane

(R,R)-N,N′-DiBoc-1-(p-methoxyphenyl)-2-(p-(p-vinylbenzyloxy)phenyl)-1,2-diaminoethaneC34H42N2O6[α]D = −4.2 (c 1.00, CHCl3)Absolute configuration: (1R,2R)Source of chirality: (R,R)-N,N′-diboc-1,2-bis(p-hydroxyphenyl)-1,2-diaminoethane

(R,R)-N,N′-DiBoc-1-(p-(p-benzyloxy)phenyl)-2-(p-(p-vinylbenzyloxy)phenyl)-1,2-diaminoethaneC40H46N2O6[α]D = −4.1(c 0.90, CHCl3)Absolute configuration: (1R,2R)Source of chirality: (R,R)-N,N′-diboc-1,2-bis(p-hydroxyphenyl)-1,2-diaminoethane

(R,R)-N,N′-DiBoc-1-(p-methoxyphenyl)-2-(p-(p-vinylphenylbutyloxy)phenyl)-1,2-diaminoethaneC37H48N2O6[α]D = −6.5 (c 1.00, CHCl3)Absolute configuration: (1R,2R)Source of chirality: (R,R)-N,N′-diboc-1,2-bis(p-hydroxyphenyl)-1,2-diaminoethane

(R,R)-N,N′-DiBoc-1-(p-hydroxyphenyl)-2-(p-(p-vinylphenylbutyloxy)phenyl)-1,2-diaminoethaneC36H46N2O6[α]D = −9.6 (c 1.00, CHCl3)Absolute configuration: (1R,2R)Source of chirality: (R,R)-N,N′-diboc-1,2-bis(p-hydroxyphenyl)-1,2-diaminoethane