542 J. Am. Chem. Soc., Vol. 123, No. 4, 2001
Nozaki et al.
Chemical Industries Ltd., Nacalai Tesque, or Aldrich Chemical Co.,
Inc., and were used without further purification unless otherwise
specified. Solvents were purified by distillation under argon after drying
over standard drying agents. Styrene which contains 0.003% of tert-
butylcatechol was used without distillation. Carbon monoxide (99.9%)
was obtained from Teisan Co. (S)-(-)-Binaphthol came from Sumikin
Chemical Co. Ltd.
NMR Data of 3a, 4, and 8a with 13CO. 3a: 31P NMR (CDCl3 at
20 °C) δ 139.9 (d, JP-P ) 64 Hz), 14.6 (dd, JP-P ) 64 Hz, JP-C ) 11
Hz); 13C NMR (CDCl3 at 20 °C) δ 237.7 (dd, JPa-C ) 11 Hz, JPb-C
)
2.4 Hz). 3b: 13C NMR (CDCl3 at 20 °C) δ 236.7 (dd, JPa-C ) 2.4 Hz,
JPb-C ) 11 Hz). 3c: 13C NMR (CDCl3 at 20 °C) δ 237.1 (dd, JPa-C
)
9.8 Hz, JPb-C ) 2.4 Hz). 4: 31P NMR (CDCl3 at 20 °C) δ 141.7 (d,
JP-P ) 98 Hz), 19.1 (dd, JP-P ) 98 Hz, JP-C ) 12 Hz); 13C NMR
(CDCl3 at 20 °C) δ 224.1 (dd, JPa-C ) 12 Hz, JPb-C ) 3.6 Hz). 8a:
31P NMR Studies on the Regioselectivity of Styrene Insertion to
Acetylpalladium [Pd(COMe)(CD3CN){(R,S)-BINAPHOS}]‚[B{3,5-
(CF3)2C6H3}4] (2) (See Also Figure 2). A solution of Pd(Me)(Cl)-
{(R,S)-BINAPHOS} (23.8 mg, 0.0257 mmol) in CH2Cl2 (1.5 mL) was
added to a solution of Na[B(3,5-(CF3)2C6H3)] (24.9 mg, 0.0281 mmol)
in CD3CN (0.5 mL). Deuterium-substituted acetonitrile was used for
NMR studies in order to avoid a CH3 peak in 1H NMR. After the
solution was stirred at 20 °C for 1 h, the solvents were removed in
vacuo to give [Pd(Me)(CD3CN){(R,S)-BINAPHOS}]‚[B{3,5-(CF3)2-
C6H3}4] (1). The complex was dissolved in CDCl3 (1.0 mL) and stirred
under CO (1 atm) for 30 min to form acetylpalladium 2. The solution
was transferred into an NMR tube under 1 atm of CO atmosphere.
Immediately after the addition of 3 equiv of styrene (0.009 mL, 0.0785
mmol), the NMR tube was placed in the NMR probe and cooled to
-10 °C. After the tube was kept at -10 °C for 3 h, the 31P NMR
spectrum showed the appearance of the 1,2-alkyl complex [Pd(CH2-
CHPhCOMe){(R,S)-BINAPHOS}]‚[B{3,5-(CF3)2C6H3}4] (3a) and the
2,1-alkyl complex [Pd(CHPhCH2COMe){(R,S)-BINAPHOS}]‚[B{3,5-
(CF3)2C6H3}4] (4). Upon warming of the solution to 20 °C, four new
species appeared, which are assigned as 3b and 3c (diastereomers of
3a) and two π-benzyl complexes [Pd(η3-CH3CHPh){(R,S)-BINAPHOS}]‚
[B{3,5-(CF3)2C6H3}4] (8a and 8b). After 44 h at 20 °C, 8a and 8b
became the only visble species. The 31P NMR charts are summarized
in Figure 2. 3a: 31P NMR (CDCl3 at 20 °C) δ 139.9 (d, JP-P ) 64
Hz), 14.6 (d, JP-P ) 64 Hz); (CDCl3 at -10 °C) δ 140.9 (d, JP-P ) 64
Hz), 14.7 (d, JP-P ) 64 Hz). 3b: 31P NMR (CDCl3 at 20 °C) δ 149.9
(d, JP-P ) 64 Hz), 30.6 (d, JP-P ) 67 Hz); (CDCl3 at -10 °C) δ 150.6
(d, JP-P ) 67 Hz), 31.7 (d, JP-P ) 64 Hz). 3c: 31P NMR (CDCl3 at 20
°C) δ 139.5 (d, JP-P ) 64 Hz), 14.9 (d, JP-P ) 64 Hz); (CDCl3 at -10
°C) δ 140.5 (d, JP-P ) 67 Hz), 15.1 (d, JP-P ) 64 Hz). 4: 31P NMR
(CDCl3 at 20 °C) δ 141.7 (d, JP-P ) 98 Hz), 19.1 (d, JP-P ) 98 Hz);
(CDCl3 at -10 °C) δ 141.9 (d, JP-P ) 98 Hz), 19.4 (d, JP-P ) 98 Hz).
8a: 31P NMR (CDCl3 at 20 °C) δ 152.4 (d, JP-P ) 95 Hz), 17.9 (d,
JP-P ) 95 Hz); (CDCl3 at -10 °C) δ 153.1 (d, JP-P ) 95 Hz), 17.9 (d,
JP-P ) 95 Hz). 8b: 31P NMR (CDCl3 at 20 °C) δ 149.5 (d, JP-P ) 98
Hz), 17.5 (d, JP-P ) 98 Hz); (CDCl3 at -10 °C) δ 150.3 (d, JP-P ) 98
Hz), 17.6 (d, JP-P ) 98 Hz). Assignment of the 31P NMR peaks to
complexes 3, 4, and 8 was performed by repeating the same experiment
using either 13C-labeled styrene (PhCHd13CH2) or 13CO as shown in
the next two paragraphs. 1H NMR of the last sample showed the
presence of 3-phenyl-3-buten-2-one (5)21 and 4-phenyl-3-buten-2-one
31P NMR (CDCl3 at 20 °C) δ 152.4 (d, JP-P ) 95 Hz), 17.9 (d, JP-P
)
95 Hz), no JP-C was observed. 8b: 31P NMR (CDCl3 at 20 °C) δ 149.5
(d, JP-P ) 98 Hz), 17.5 (d, JP-P ) 98 Hz), no JP-C was observed.
Preparation of the Authentic Sample of 1,2-Ester 14. First, methyl
3-phenyl-4-pentenoate (18) was prepared. A mixture of cinnamyl
alcohol (17, 10.2 g, 76.5 mmol) with 1.5 equiv of trimethyl orthoacetate
(15 mL, 117 mmol) and 0.04 equiv of propionic acid (0.4 mL, 5.36
mmol) was gradually heated to 140 °C and then kept at 140-150 °C
for 21 h. Water was added to the reaction mixture, and the aqueous
layer was extracted with ether. The combined organic layers were
washed with saturated aqueous NaHCO3 and saturated aqueous NaCl,
dried over magnesium sulfate, and concentrated under reduced pressure
to give methyl 3-phenyl-4-pentenoate (18) as the crude product (ca.
82% yield). The terminal C-C double bond was transformed into an
acetyl group via a Wacker process. A mixture of PdCl2 (1.12 g, 6.33
mmol) and CuCl (6.24 g, 63.1 mmol) in aqueous dimethylformamide
(DMF/H2O ) 7/1, total 50 mL) was stirred under an oxygen balloon
at room temperature for 2.5 h until the suspension turned a green-
brown color. Crude 18 (12 g, 62.8 mmol), obtained above, was added
within 20 min by additional funnel, accompanied by vigorous stirring
under an oxygen balloon at room temperature. The solution turned
green-brown to black within 20 min and then returned gradually to
green-brown. After being stirred for 4 days, the mixture was poured
into aqueous 1 M HCl and extracted with diethyl ether. The combined
organic layers were washed with saturated aqueous NaHCO3 and
saturated aqueous NaCl, dried over magnesium sulfate, and concentrated
under a reduced pressure. The crude product was purified by distillation
(89-90 °C, 0.7 Torr) to give methyl 3-phenyl-4-oxopentanoate (14,
2.61 g, 12.7 mmol) in 20% yield: 1H NMR (CDCl3, at 20 °C) δ 2.12
(s, 3H), 2.53 (dd, JH-H ) 16.8, 5.0 Hz, 1Η), 3.22 (dd, JH-H ) 16.8,
9.8 Hz, 1Η), 3.65 (s, 3H), 4.19 (dd, JH-H ) 9.7, 5.0 Hz, 1Η), 7.2-7.4
(m, 5H); 13C NMR (CDCl3, at 20 °C) δ 28.8, 36.7, 51.7, 54.8, 127.7,
128.2, 129.1, 137.3, 172.5, 206.8; IR (neat) 1733, 1715, 1595, 1490
cm-1. Elemental analysis, calcd for C12H14O3: C, 69.89; H, 6.84.
Found: C, 69.81; H, 6.93.
Hydrolysis of Ester 14 to Acid 19. A mixture of methyl ester 14
(711 mg, 3.45 mmol) with KOH, MeOH, and H2O was stirred for 1 h
at room temperature. The mixture was poured into aqueous 1 M HCl
and extracted with ether. The combined organic layers were washed
with saturated aqueous NaCl, dried over magnesium sulfate, and
concentrated under reduced pressure to give 19 quantitatively: 1H NMR
(DMSO-d6, at 20 °C) δ 2.02 (s, 3H), 2.45 (dd, JH-H ) 16.9, 5.3 Hz,
1Η), 2.99 (dd, JH-H ) 16.9, 9.9 Hz, 1Η), 4.18 (dd, JH-H ) 9.7, 4.9
Hz, 1Η), 7.22-7.43 (m, 5H), 12.23 (s, 1H); 13C NMR (DMSO-d6, at
20 °C) δ 28.1, 36.5, 53.8, 127.4, 128.2, 128.9, 131.8, 172.8, 206.8; IR
(Nujol) 3400-2700, 1730, 1685 cm-1. Elemental analysis, calcd for
C11H12O3: C, 68.74; H, 6.29. Found: C, 68.53; H, 6.34.
1
(benzalacetone 6). H NMR of 6 available from Aldrich: (CDCl3 at
20 °C) δ 2.39 (s, 3H), 6.72 (d, J ) 16.5 Hz, 1H), 7.36-7.43 (m, 3H),
7.46-7.59 (m, 3H). Because only the NMR data in CCl4 were reported
in the literature,21 we prepared 5 in order to compare the chemical shifts
1
in CDCl3. H NMR of 3-phenyl-3-buten-2-one (5): (CDCl3 at 20 °C)
δ 2.45 (s, 3H), 5.97 (d, J ) 0.4 Hz, 1H), 6.18 (d, J ) 0.5 Hz, 1H),
7.25-7.40 (m, 5H).
NMR Data of 3, 4, and 8 with Styrene-2-13C (PhCHd13CH2).
3a: 31P NMR (CDCl3 at 20 °C) δ 139.9 (dd, JP-P ) 64 Hz, JP-C ) 6.1
Hz), 14.6 (dd, JP-P ) 64 Hz, JP-C ) 80 Hz); 13C NMR (CDCl3 at 20
°C) δ 39.3 (dd, JP-C ) 80 and 6.1 Hz). 3b: 31P NMR (CDCl3 at 20
°C) δ 149.9 (dd, JP-P ) 64 Hz, JP-C ) 128 Hz), 30.6 (dd, JP-P ) 67
Optical Resolution of 19 by Preferential Crystallization with (R)-
(+)-Phenethylamine. Acid 19 (301 mg, 1.57 mmol) was dissolved in
i-PrOH (1.5 mL). To the solution was added 1.04 equiv of (R)-(+)-
1-phenethylamine (0.21 mL, 1.63 mmol), and the solution was heated.
The solution was cooled to room temperature and allowed to stand for
24 h. The resulting colorless solids were collected by filtration, washed
with drops of i-PrOH, and dried to give (-)-CH3COCHPhCH2COO-‚
(R)-(+)-1-phenethylammonium salts as colorless solids (305 mg, 0.975
mmol). The salts were neutralized with aqueous 6 M HCl, and the
carboxylic acid was extracted with ether. Removal of the solvent
afforded (R)-(-)-19 (124 mg, 0.643 mmol) with 27% ee (determined
by gas chromatography using a chiral column, Chrompak, CP-
Hz, JP-C ) 3.1 Hz); 13C NMR (CDCl3 at 20 °C) δ 49.1 (dd, JP-C
)
127, 4.9 Hz). 3c: 31P NMR (CDCl3 at 20 °C) δ 139.5 (dd, JP-P ) 64
Hz, JP-C ) 6.1 Hz), 14.9 (dd, JP-P ) 64 Hz, JP-C ) 79 Hz); 13C NMR
(CDCl3 at 20 °C) δ 39.8 (dd, JP-C ) 79, 6.1 Hz). 4: 31P NMR (CDCl3
at 20 °C) δ 141.7 (d, JP-P ) 98 Hz), 19.1 (dd, JP-P ) 98 Hz, JP-C
)
6.1 Hz); 13C NMR (CDCl3 at 20 °C) δ 51.8 (d, JP-C ) 6.1 Hz). 8a:
31P NMR (CDCl3 at 20 °C) δ 152.4 (d, JP-P ) 95 Hz), 17.9 (dd, JP-P
) 95 Hz, JP-C ) 6.1 Hz); 13C NMR (CDCl3 at 20 °C) δ 16.2 (d, JP-C
) 6.1 Hz, CH3 by DEPT). 8b: 31P NMR (CDCl3 at 20 °C) δ 149.5 (d,
JP-P ) 98 Hz), 17.5 (dd, JP-P ) 98 Hz, JP-C ) 6.1 Hz); 13C NMR
(CDCl3 at 20 °C) δ 18.5 (d, JP-C ) 6.1 Hz, CH3 by DEPT).
Cyclodextrin-â-236M, 159 °C). [R]20 ) -167.55 (c 0.45, CHCl3).
D
The absolute configuration was determined to be R by comparing the
optical rotation with related compounds (see Figure 4).