X. Li et al. / Tetrahedron: Asymmetry 11 (2000) 2077±2082
2081
13C NMR (CDCl3): 20.792, 21.581, 25.973, 27.210, 30.116, 41.328, 45.486, 49.651, 57.161,
175.032 ppm; calcd for C11H19NO2: C, 66.97; H, 9.71; N, 7.10. Found: C, 67.13; H, 9.75; N,
6.98.
3.3. (1S,2R)-1-(N-Methyl aminomethyl)-2-hydroxyl-7,7-dimethylbicyclo[2.2.1]heptane 4
.
A solution of borane THF complex (15 ml, 1 M in THF) was added to a solution of 1.56 g
compound 3 (8 mmol in 10 ml of dry THF). The mixture was stirred at room temperature for 12
h and then was quenched with 2N hydrogen chloride. The solution was diluted with dichloro-
methane and then sodium carbonate was added to make the pH of the solution about 9±10. The
organic layer was separated and the water layer was extracted with CHCl3 (3Â15 ml). Concentration
and chromatography of the crude product (methanol:ethyl acetate, 2:1) aorded compound 4
ꢀ
1
1.32 g (90% yield). Mp=74±76 C; [ꢀ]D=^24.2 (c=0.66, CHCl3); H NMR (400 MHz, CDCl3):
0.84 (s, 3H), 1.09±1.13 (m, 2H), 1.16 (s, 3H), 1.45±1.46 (m, 1H), 1.66±1.70 (m, 3H), 1.71±1.82 (m,
1H), 2.47 (s, 3H), 2.51±2.58 (d, J=2.612 Hz, 1H), 3.06±3.09 (d, J=2.412 Hz, 2H), 3.90±4.07 (dd,
J=3.748, 3.756 Hz, 1H); MS (ESI): 184 (M+1,100); exact mass calculated for C11H21NO:
183.1623. Found: 183.1621.
3.4. Preparation of N,O-bis(diphenylphosphino)-(1S,2R)-1-(N-methylamino)methyl-2-hydroxyl-
7,7-dimethylbicyclo[2.2.1]heptane 5
92 mg of exo-4 (0.50 mmol) was placed in a Schlenk ¯ask and an inert atmosphere was intro-
duced by three cycles of vacuum/argon. Triethylamine (0.13 ml, 0.90 mmol) in 3 ml of anhydrous
benzene was added. The reaction mixture was stirred well and cooled to 0ꢀC with an ice bath. A
solution of 0.16 ml of chlorodiphenylphosphine (0.90 mmol) in 1 ml of anhydrous benzene was
added dropwise to the mixture. After all of the chlorodiphenylphosphine was added, the ice bath
was removed and the stirring was continued at ambient temperature for 24 h. Filtration of the
triethylammonium chloride followed by ¯ash column chromatography on silica gel (benzene as
1
eluent) gave 160 mg of 5 (58%). 31P NMR (CDCl3): 74.29 (s, P (N)), 115.21 (s, P(O)) ppm; H
NMR (CDCl3): 0.86±0.92 (m, 1H), 0.93 (s, 3H), 1.06±1.09 (m, 1H), 1.24 (s, 3H), 1.45±1.52 (m,
1H), 1.85±1.86 (m, 1H), 2.46±2.47 (d, J=4.12 Hz, 3H), 3.37±3.45 (dd, J=14.61, 15.54 Hz, 1H),
3.67±3.74 (dd, J=12.65, 12.59 Hz), 4.26±4.28 (m, 1H), 7.08±7.66 (m, 20H) ppm. C35H39NOP2
(551.6483), calcd: C, 76.21; H, 7.13; N, 2.54; P, 11.23. Found: C, 75.94; H, 7.18; N, 2.52; P,
11.16.
3.5. Typical procedures for the prepation of catalyst and for asymmetric catalytic hydrogenation
In an inert atmosphere glove box, [Rh(COD)2]BF4 (4.1 mg, 0.01 mmol) and exo-5 (5.9 mg,
0.0105 mmol) were dissolved in 1 ml of anhydrous acetone. After 10 min of stirring, the solution
of [Rh(COD)(exo-5)]BF4 obtained was ready for use in asymmetric hydrogenation. In a 50 ml
stainless steel autoclave were added the substrate methyl (Z)-2-acetaminocinnamate (0.1 mmol),
0.1 ml (0.001 mmol) of catalyst solution prepared above and 1 ml of the degassed acetone under
nitrogen atmosphere. The vessel was pressurized with 500 psi of H2 and the reaction was carried
out at room temperature for 7 h. The e.e. value and the conversion level were determined
by chiral GLC analysis with a Chirasil-L-Val column or HPLC analysis with a Chiralcel OD
column.