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18. (S)-2,2%-Bis[bis(3,5-dimethylphenyl)phosphinoamino]-1,1%-
binaphthyl[(S)-Xyl-BDPAB], (S)-3. To a 50 ml round-
bottom Schlenk flask containing (S)-1,1%-binaphthyl-
2,2%-diamine (200 mg, 0.7 mmol) and DMAP (10 mg)
were added 10 ml dried CH2Cl2 and 0.7 ml dried Et3N.
The solution was cooled with an ice-bath to 0°C. Bis(3,5-
dimethylphenyl)phosphine chloride (450 mg, 1.6 mmol)
was added in a dropwise manner within 15 min. The
reaction mixture was stirred at room temperature for 3 h,
and the solvent was evaporated in vacuo. The residue was
purified using a flash silica gel column (toluene as the
eluent) under N2. Concentration of the filtrate and
removal of solvent under vacuum overnight gave (S)-3
(465 mg, 87% yield). Colorless crystals were obtained by
recrystallization from methanol/CH2Cl2 (v/v=4). 31P
NMR (CHCl3): l 26.1 (s). H NMR (CHCl3): l 2.35 (s,
1
12H), 2.8 (s, 12H), 5.00 (d, J=8.5 Hz, 2H), 6.96 (s, 2H),
6.98 (s, 2H), 7.00 (s, 2H), 7.01 (s, 2H), 7.04 (s, 2H), 7.10
(s, 2H), 7.42 (d, J=8.5 Hz, 2H), 7.50 (d, J=8.5 Hz, 2H),
7.56 (d, J=8.0 Hz, 2H), 8.10 (d, J=8.0 Hz, 2H), 8.18 (d,
J=9.0 Hz, 2H), 8.24–8.27 (dd, J=4.5, 9.0 Hz, 2H). 13C
NMR (CHCl3): methyl carbons 21.09, 21.11.
19. (S)-2,2%-Bis(dicyclohexylphosphinoamino)-1,1%-binaphthyl
[(S)-Cy-BDPAB], (S)-2. (S)-2 was synthesized in 78%
yield using a method similar to the preparation of (S)-3.
Colorless crystals were obtained by recrystallization from
ether. 31P NMR (CH2Cl2): l 42.77; 1H NMR (CH2Cl2): l
0.21–0.27 (m, 2H), 0.56–0.61 (m, 2H), 0.73–1.60 (m,
40H), 3.77 (d, J=10.5 Hz, 2H), 6.84 (d, J=7.5 Hz, 2H),
7.03–7.10 (m, 4H), 7.67 (d, J=7.5 Hz, 2H), 7.73 (d,
J=9.5 Hz, 2H), 7.78–7.81 (dd, J=4.5, 9.0 Hz, 2H).
20. A typical procedure for the rhodium-catalyzed asymmetric
hydrogenation of amidoacrylic acids and esters. In a glove-
box 0.01 mmol [Rh(COD)2]BF4, 0.01 mmol of the
bisaminophosphine ligand and 1 ml dried CH2Cl2 were
placed in a 4 ml glass bottle and the mixture was stirred
at room temperature for 1 h to prepare a stock solution
of the catalyst. In a typical experiment, 10 ml (0.0001
mmol) of the catalyst solution was added in a 50 ml
autoclave which was charged with 0.05 mmol substrate
and 190 ml solvent. The autoclave was closed and the
atmosphere was displaced by hydrogen several times and
finally 50 psig H2 was charged. The mixture was stirred at
rt for 10 min before releasing the H2. The enantiomeric
excess and conversion were determined by GC. The
hydrogenation product of acetamidoacrylic acid was con-
verted to its methyl ester before the GC analysis with a
capillary chiral column (CHROMPACK, CP Chirasil-
DEX CB, 25 m×0.25 mm). Other hydrogenation products
were analyzed using a (CHROMPACK, Chirasil-L-Val,
25 m×0.25 m) column.