Tunable dendritic ligands of chiral 1,2-diamine and their application in asymmetric transfer hydrogenation

Tunable dendritic N-mono-sulfonyl ligands have been designed and synthesized via direct N-mono-sulfonylization of the chiral dendritic vicinal diamines and their ruthenium complexes demonstrated high catalytic and recyclable activities with comparable enantioselectivities to Noyori–Ikariya’s TsDPEN-Ru in the asymmetric transfer hydrogenation of an extended range of substrates, such as ketones, keto esters, and olefins.

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(1R,2R)-N-[2-Amino-1,2-bis-(4-methoxyphenyl)ethyl]-4-methylbenzenesulfonamideC23H26N2O4S[α]D22=+121.8 (c 0.67, CHCl3)Source of chirality: (R,R)-1,2-bis(4-methoxyphenyl)ethane-1,2-diamineAbsolute configuration: 1R,2R

(1R,2R)-N-[2-Amino-1,2-bis-(4-benzyloxyphenyl)ethyl]-4-methylbenzenesulfonamideC35H34N2O4S[α]D22=+65.7 (c 0.55, CHCl3)Source of chirality: (R,R)-1,2-bis(4-methoxyphenyl)ethane-1,2-diamineAbsolute configuration: 1R,2R

(1R,2R)-N-{2-Amino-1,2-bis-[4-(3,5-bisbenzyloxybenzyloxy)phenyl]ethyl}-4-methylbenzenesulfonamideC63H58N2O8S[α]D22=+3.0 (c 1.2, CHCl3)Source of chirality: (R,R)-1,2-bis(4-methoxyphenyl)ethane-1,2-diamineAbsolute configuration: 1R,2R

(1R,2R)-N-{2-Amino-1,2-bis-[4-[3,5-bis(3,5-bisbenzyloxybenzyloxy)benzyloxy]phenyl]ethyl}-4-methylbenzenesulfonamideC119H106N2O16S[α]D22=+7.9 (c 1.2, CHCl3)Source of chirality: (R,R)-1,2-bis(4-methoxyphenyl)ethane-1,2-diamineAbsolute configuration: 1R,2R

(1R,2R)-N-{2-Amino-1,2-bis-[4-[3,5-bis[3,5-bis(3,5-bis-benzyloxybenzyloxy)benzyloxy]benzyloxy]phenyl]ethyl}-4-methylbenzenesulfonamideC231H202N2O32S[α]D22=+0.3 (c 2.24, CHCl3)Source of chirality: (R,R)-1,2-bis(4-methoxyphenyl)ethane-1,2-diamineAbsolute configuration: 1R,2R

(1S,2S)-N-{2-Amino-1,2-bis-[4-[3,5-bis(3,5-bisbenzyloxybenzyloxy)benzyloxy]phenyl]ethyl}-2,4,6-triethylbenzenesulfonamideC124H116N2O16S[α]D25=-16.7 (c 1.0, CHCl3)Source of chirality: (S,S)-1,2-bis(4-methoxyphenyl)ethane-1,2-diamineAbsolute configuration: 1S,2S

(1S,2S)-N-{2-Amino-1,2-bis-[4-[3,5-bis(3,5-bisbenzyloxybenzyloxy)benzyloxy]phenyl]ethyl}-2,4,6-triisopropylbenzenesulfonamideC127H122N2O16S[α]D25=-23.0 (c 3.0, CHCl3)Source of chirality: (S,S)-1,2-bis(4-methoxyphenyl)ethane-1,2-diamineAbsolute configuration: 1S,2S

(1S,2S)-N-2-Amino-1,2-bis-[4-[3,5-bis(3,5-bisbenzyloxybenzyloxy)benzyloxy]phenyl]ethyl naphthalene-1-sulfonamideC122H106N2O16S[α]D25=-44.6 (c 1.15, CHCl3)Source of chirality: (S,S)-1,2-bis(4-methoxyphenyl)ethane-1,2-diamineAbsolute configuration: 1S,2S