The pentafluorophenyl group as a module for the direct modification of chiral diamines for asymmetric catalysis

A pentafluorophenyl group embedded in a chiral diamine allows the direct modification of an aryl group. The diamine is readily converted into para-disubstituted diamines. Although the electronic effect of the modified diamine somewhat lowers the catalytic activity of BINAP–Ru–diamine-catalyzed asymmetric hydrogenation, the enantioselectivity of the product is higher than that obtained by using a typical chiral diamine. Such an easy and direct modification of the chiral ligand has the potential to facilitate the optimization of the steric effect of chiral ligands in asymmetric catalysis.

Figure optionsDownload as PowerPoint slide

(1S,2S)-1,2-Bis(4-methoxy-2,3,5,6-tetrafluorophenyl)ethane-1,2-diamineC16H12F8N2O2Ee >99%[α]D20=-85.8 (c 0.50, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)

(1S,2S)-1,2-Bis(4-isopropoxy-2,3,5,6-tetrafluorophenyl)ethane-1,2-diamineC20H20F8N2O2Ee >99%[α]D30=-92.5 (c 0.21, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)

(1S,2S)-1,2-Bis(4-(pentan-3-yloxy)-2,3,5,6-tetrafluorophenyl)ethane-1,2-diamineC24H28F8N2O2Ee >99%[α]D16=-51.4 (c 1.6, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)

(1S,2S)-1,2-Bis(4-benzhydryloxy-2,3,5,6-tetrafluorophenyl)ethane-1,2-diamineC40H28F8N2O2Ee >99%[α]D32=-41.9 (c 0.19, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)

(1S,2S)-1,2-Bis(4-neopentyloxy-2,3,5,6-tetrafluorophenyl)ethane-1,2-diamineC24H28F8N2O2Ee >99%[α]D30=-89.2 (c 0.45, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)

(1S,2S)-1,2-Bis(4-cyclopentyloxy-2,3,5,6-tetrafluorophenyl)ethane-1,2-diamineC24H24F8N2O2Ee >99%[α]D31=-77.2 (c 0.54, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)

(1S,2S)-1,2-Bis(4-cyclohexyloxy-2,3,5,6-tetrafluorophenyl)ethane-1,2-diamineC26H28F8N2O2Ee >99%[α]D32=-80.2 (c 0.13, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)

(1S,2S)-1,2-Bis(2,3,5,6-tetrafluoro-4-(3,3,5,5-tetramethylcyclohexyloxy)phenyl)ethane-1,2-diamineC34H44F8N2O2Ee >99%[α]D32=-95.8 (c 0.78, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)

(1S,2S)-1,2-Bis(4-(2,3-dihydro-1H-inden-2-yloxy)-2,3,5,6-tetrafluorophenyl)ethane-1,2-diamineC32H24F8N2O2Ee >99%[α]D32=-72.8 (c 0.18, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)

(1S,2S)-1,2-Bis(4-((S)-1-phenylethoxy)-2,3,5,6-tetrafluorophenyl)ethane-1,2-diamineC30H24F8N2O2Ee >99%[α]D32=-177.3 (c 0.23, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)

(1S,2S)-1,2-Bis(4-((R)-1-phenylethoxy)-2,3,5,6-tetrafluorophenyl)ethane-1,2-diamineC30H24F8N2O2Ee >99%[α]D32=+63.9 (c 0.55, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)

(1S,2S)-1,2-Bis(2,3,5,6-tetrafluorophenyl)ethane-1,2-diamineC14H8F8N2Ee >99%[α]D18=-61.9 (c 1.8, MeOH)Source of chirality: enantiopure starting materialAbsolute configuration: (1S,2S)