C2-symmetric bisphosphine ligands derived from 1,1- binaphthyldiamines and diphenylphosphinobenzoic acid for palladium catalyzed desymmetrizations

Article abstract of DOI:10.1016/S0040-4020(00)00420-8

A series of novel C₂-symmetric bisphosphine ligands derived from DPPBA and C₂-symmetric 1,1' -binaphthyldiamines has been synthesized. In palladium catalyzed desymmetrization of meso cyclic carbamates, the enantioselectivity and the stereochemistry of the major enantiomers are largely affected by the substitution position of DPPBA moiety on the 1,1'-binaphthyl chiral scaffold. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(00)00420-8

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 5131±5136
C2-Symmetric Bisphosphine Ligands Derived from
1,10-Binaphthyldiamines and Diphenylphosphinobenzoic Acid for
Palladium Catalyzed Desymmetrizations
*
Chung Woo Lim and Sang-gi Lee
Life Sciences Division, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, 130-650 Seoul, South Korea
Received 12 April 2000; accepted 18 May 2000
AbstractÐA series of novel C2-symmetric bisphosphine ligands derived from DPPBA and C2-symmetric 1,10-binaphthyldiamines has been
synthesized. In palladium catalyzed desymmetrization of meso cyclic carbamates, the enantioselectivity and the stereochemistry of the major
enantiomers are largely affected by the substitution position of DPPBA moiety on the 1,10-binaphthyl chiral scaffold. q 2000 Elsevier
Science Ltd. All rights reserved.
Introduction
are highly sensitive to small structural change of the ligands.
For example, simply inverting of the amide linker of the
DPPBA derived ligands but keeping everything else the
same inverts the sense of chiral recognition and increases
enantioselectivity which may be due to the change of the
P±Pd±P bite-angles of the Pd-complexes formed with
bisphosphine ligands.5 Therefore, we expected that
changing the substitution positions of DPPBA moiety on
1,10-binaphthyl scaffold from 2,20- to 6,60- or 7,70-positions
may have effects on the enantioselectivity in palladium-
catalyzed desymmetrization of meso-compounds. In
ongoing efforts to develop C2-symmetric chiral ligands for
asymmetric catalysis,7 we decided to examine the differen-
tial ionization ability of the ligands in which the DPPBA
moiety placed at different positions on 1,10-binaphthyl
chiral scaffold. Herein, we report on the preparation of
bisphosphine ligands 3±6 and their catalytic acitvities in
Pd-catalyzed desymmetrization of meso-cyclic biscarba-
mates 16a±c (Fig. 1).
Increased hindrance to rotation at the pivotal 1,10-bond can
make the 2,20-substituted 1,10-binaphthyls resolvable as
optically active enantiomers. Because of their highly stable
chiral con®guration, they have been extensively used to
control many asymmetric processes and have demonstrated
outstanding chiral discrimination properties. For example,
bidentate diphosphine, BINAP, has been utilized as a chiral
ligand in Rh(I)- or Ru(II)-catalyzed asymmetric hydrogena-
tions, double bond isomerizations, and numerous other
asymmetric catalytic reactions.1 Despite the great success
that the bisphosphine ligands possessing a 1,10-binaphthyl
chiral scaffold have enjoyed over the years, less satisfactory
results have been reported for their application in Pd(0)-
catalyzed allylic substitutions, especially, desymmetrization
of meso-compounds.2±4
Recently, for Pd(0)-catalyzed allylic substitutions and
desymmetrization of cyclic meso-compounds, Trost
developed highly ef®cient bisphosphine ligands derived
from 2-(diphenylphosphino)benzoic acid (DPPBA) and
various chiral diamines or their amide linker invertomers
from 2-(diphenylphosphino)aniline (DPPA) and chiral
dicarboxylic acids.5,6 However, in Pd(0)-catalyzed desym-
metrization of meso-cyclopenten-1,3-diol bis(carbamate)
16a (Scheme 2), the 2,20-substituted 1,10-binaphthyl ligands
such as BINAPO (55% ee),4a 1 (40% ee)4b and 2 (30% ee)4c
afforded low to moderate enantioselectivities. It has been
found that the enantiodiscrimination abilities of the ligands
Results and Discussion
The ligand 3 was prepared from commercially available
(R)-1,10-binaphthyl-2,20-diamine and 2-(diphenylphos-
phino)benzoic acid (DPPBA) using DCC in 59% yield.
For the synthesis of (R)-7,70-disubstituted-2,20-dimethoxy-
1,10-binaphthyl ligands 4 and 5, optically pure 7,70-bis-
(benzyloxy)-2,20-dihydroxy-1,10-binaphthyl, (R)-7, has
been chosen as a key intermediate. The (R)-7 could be
synthesized from 7-benzyloxy-2-naphthol8 via oxidative
coupling followed by resolution. Initially, the 7-benzyl-
Keywords: C2-symmetric; binaphthylbisphosphine; palladium; desymme-
trizations.
* Corresponding author. Tel.: 182-2-958-5163; fax: 182-2-958-5189;
e-mail: sanggi@kist.re.kr
8a
oxy-2-naphthol was oxidatively coupled using Mn(acac)3
to obtain rac-7, but the coupling
8b,9c
or t-BuNH2±CuCl2
yields were low (35±60%).9 However, when the coupling
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00420-8

5132
C. W. Lim, S. Lee / Tetrahedron 56 (2000) 5131±5136
hydroxy-2,20-dimethoxy-1,10-binaphthyl 9 in 91% yield.
DCC coupling of 9 with DPPBA afforded ligand 4 in 68%
yield. To introduce the amine functional group of the 7,70-
diamine 12, the dihydroxy compound 9 was converted to the
corresponding bis(tri¯ate) 10 using Tf2O.8d,13 For the
Buchward14,15 and Hartwig16 aryl amination of bis(tri¯ate)
10 with benzylamine, initially, we employed bis[2-(di-
phenylphosphino)phenyl]ether (DPEphos)14 and Pd(OAc)2
catalyst. However, the monoaminated product was formed
as a major product. Fortunately, reaction of 10 with benzyl-
amine in the presence of NaO-t-Bu and a combination of
Pd2(dba)3 (dbaˆdibenzylideneacetone) and DPPF (DPPFˆ
1,10-bis(diphenylphosphino)ferrocene) in toluene afforded
the desired diaminated product 11 in 92% yield without
any loss of optical purity. Debenzylation of 11 using
Pd±C/H2 in methanol afforded the diamine 12, which was
used for the next reactions without further puri®cation. DCC
coupling of the diamine 12 with DPPBA afforded bis-
phosphine ligand 5 in 68% yield. As shown in Scheme 1,
optically pure 6,60-disubstituted-2,20-dimethoxy-1,10-
binaphthyl ligand (R)-6 was easily prepared starting from
an optically pure (R)-6,60-dibromide 13, which was
prepared by bromination of commercially available (R)-
1,10-bi-2-naphthylol according to the reported procedure.17
Figure 1.
reaction was carried out under the reaction conditions
reported by Nakajima,10 i.e. using 1 mol% of CuCl(OH)´T-
MEDA catalyst and O2, the oxidative coupling occurred
ef®ciently to give rac-7 in 92% yield. Among the numerous
ef®cient methods for the optical resolution of rac-1,10-bi-2-
naphthol to optically pure enantiomer,11 the rac-7 was
resolved to optically pure (R)-(2)-7 through clathrate
formation with quinine.12 Methylation of (R)-(2)-7 with
excess methyl iodide in the presence of K2CO3 in DMF
afforded (R)-(2)-7,7-bis(benzyloxy)-2,20-dimethoxy-1,10-
binaphthyl 8 almost quantitatively.8d Debenzylation of
8 performed with Pd(OH)2/H2 to give (R)-(2)-7,70-di-
The catalytic ef®ciencies of these DPPBA-derived 1,10-
binaphthyl bisphosphine ligands 3,4,5 and 6 have been
examined in Pd(0)-catalyzed desymmetrizations of meso-
cyclic carbamates 16a±c18 (Scheme 2). The desymmetriza-
tion reactions have been carried out with the molar ratios
of Pd2(dba)3´CHCl3: ligand:substrateˆ2.5:7.5:100 in THF
solvent at 208C in the presence of Et3N. The results are
summarized in Table 1. Desymmetrization of ®ve-
membered meso-carbamate 16a using ligand 3 afforded
17a as a major isomer with 14% ee (entry 1). When
the ligand was changed to 4, which has ester linker, the
Scheme 1. (a) CuCl(OH)´TMEDA (1 mol%), O2, CH2Cl2; (b) resolution using quinine; (c) NaH, MeI, DMF; (d) Pd(OH)2±C/H2, MeOH; (e) Tf2O, pyridine,
CH2Cl2; (f) Pd2(diba)3, DPPF, PhCH2NH2, toluene; (g) Pd±C/H2, CH3OH; (h) DPPBA, DCC, DMAP, CH2Cl2.

C. W. Lim, S. Lee / Tetrahedron 56 (2000) 5131±5136
5133
Scheme 2.
enantioselectivity was slightly increased to 24% ee, but the
major isomer was ent-17a (entry 2). The more dramatically
increased enantioselectivity (76% ee) has been observed
using ligand 5 (entry 4). The effects of reaction temperatures
and bases on the enantioselectivity have been examined
using 7,70-derived ligand 5. Comparing entries 3,4 and 5
indicate that the enantioselectivities were not dependent
on the reaction temperature, but largely on the base.3h
Thus, the same reactions without Et3N (54% ee, entry 6)
or with BSA/KOAc (34% ee, entry 7) caused decreasing of
the enantioselectivities. Desymmetrization of 16a using
6,60-derived ligand 6 afforded 17a as a major isomer with
30% ee (entry 8). Interesting is the absolute con®guration of
the product 17a. Comparing entries 1, 2, 4 and 8 show that
maintaining the same axial chirality of the chiral scaffold
and only changing the substitution position of the DPPBA
moiety reverses the sense of chirality in the product.
However, at present time, the origin of the reverse chirality
of the product cannot be explained simply. It has been also
found that as increasing the ring size of the substrates, the
enantioselectivities and reactivities were decreased. The
superiority of the 7,70-derived ligands 4 and 5 was main-
tained in the desymmetrization of the 6- and 7-membered
substrates, 16b (compare entries 9±12) and 16c (compare
entries 13±16). In palladium catalyzed allylic substitutions,
since bond breaking and bond making occur distal to palla-
dium, the chiral ligands forcing the chiral environment to
embrace the substrate by opening the bite-angle are neces-
sary for high chiral recognition. Unfortunately, we do not
have solid evidences that the real bite-angle of ligand 5 is
increased compared with 3. Nevertheless, the observed
results indicate that changing the substitution positions of
the DPPBA moiety from 2,20- to 7,70-positions on
binaphthyl scaffold enhanced the depth of the chiral pocket
in which the substrate must reside, thus, more effectively
creating a chiral space to control the enantioselectivity.
Therefore, the lower enantiodiscrimination ability of the
2,20-derived 1,10-binaphthyl bisphosphine chiral ligands
may be related with small P±Pd±P bite-angles.
Conclusion
In summary, we have synthesized a series of C2-symmetric
chiral binaphthyl-bisphosphine ligands 3±6 having appar-
ently different bite-angles. In Pd(0)-catalyzed desymmetri-
zation of meso-cyclic carbamates 16a±c, the enantio-
selectivities are dramatically increased by changing the
substitution position of the DPPBA moiety on the 1,10-
binaphthyl chiral scaffold from 2,20- (3) to 7,70-positions
(5). However, the 6,60-derived ligand 6 showed the lower
enantiodiscrimination ability than the ligand 5. Moreover, it
has been found that only changing the substitution position
of the DPPBA moiety reverses the sense of chirality in the
product.
Table 1. Pd(0)-catalyzed desymmetrization of meso-bis(carbamates) using
bisphosphine ligands 3±6
Entrya
Ligand
Substrate
Yield (%)b
17/ent-17 (% ee)c
1
3
4
5
5
5
5
5
6
3
4
5
6
3
4
5
6
16a
16a
16a
16a
16a
16a
16a
16a
16b
16b
16b
16b
16c
16c
16c
16c
72
72
84
87
93
71
64
64
70
88
74
68
64
91
72
58
57/43 (14)
38/62 (24)
12/88 (76)
12/88 (76)
13/87 (74)
23/77 (54)
33/67 (34)
65/35 (30)
55/45 (10)
24/76 (52)
19/81 (62)
47/53 (6)
2
3d
4
Experimental
5e
6f
7g
8
General
9
1H NMR, 13C NMR and 31P NMR spectra were recorded on
a Bruker 300 MHz spectrometer, IR spectra were recorded
on a MIDAC 101025 FT-IR spectrometer and optical rota-
tion was measured with Autopolw polarimeter. Chemical
analyses were carried out by the Advanced Analysis Center
at KIST. HRMS (FAB) analysis has been carried out by the
Mass Spectrometry Analysis Group at Korea Basic Science
Institute. Melting points taken on a Thomas±Hoover capil-
lary melting point apparatus are uncorrected. The reactions
were carried out using standard Schlenk techniques under
nitrogen atmosphere. Commercially available (R)-2,20-
diamino-1,10-binaphthyl and 2-(diphenylphosphino)benzoic
acid were used without puri®cation. Optically pure (R)-6,60-
dibromo-2,20-dihydroxy-1,10-binaphthyl 13 was prepared
by bromination of commercially available (R)-1,10-bi-2-
naphthylol.18 7-Benzyloxy-2-naphthol was prepared from
10
11
12
13
14
15
16
Racemic
30/70 (40)
29/71 (42)
44/56 (12)
a The reactions were carried out in THF with the molar ratios of
Pd2(dba)3´CHCl3:ligand:substrateˆ2.5:7.5:100 in the presence of
Et3N at 208C unless otherwise noted.
b Isolated yields.
c Determined by chiral HPLC using Chiralpak AD column.5h
d Reaction carried out at 08C.
e Reaction carried out at 408C.
f Reaction carried out without Et3N.
g Reaction carried out using BSA/KOAc (BSAˆN,N-bis(trimethyl-
silyl)acetamide) instead of Et3N.

5134
C. W. Lim, S. Lee / Tetrahedron 56 (2000) 5131±5136
2,7-dihydroxynaphthalene according to the reported pro-
cedure.8b
A mixture of 8 (4.52 g, 8.6 mmol) and catalytic amount of
Pd(OH)2/C in methanol (100 mL) was stirred under the
hydrogen atmosphere (1 atm) for overnight. After ®ltration
of the catalyst through Celite, the ®ltrate was concentrated
to give pure 9 (2.73 g, 91%) as a white solid. Mp 219±
2208C; [a]2D5ˆ253.5 (c 0.28, CH3OH); 1H NMR
(300 MHz, DMSO-d6) d 9.36 (bs, 2H), 7.89 (d, Jˆ8.9 Hz,
2H), 7.78 (d, Jˆ8.8 Hz, 2H), 7.33 (d, Jˆ8.9 Hz, 2H), 6.89
(Jˆ8.8 Hz, 2H), 5.77 (bs, 2H), 3.68 (s, 6H) ppm; 13C NMR
(75.5 MHz, DMSO-d6) d 156.50, 155.80, 136.08, 130.42,
129.68, 124.60, 128.21, 117.03, 111.72, 106.72, 56.89 ppm;
IR(KBr) 3384(OH); HRMS(FAB1) Calcd for C22H18O4:
346.1205. Found: 346.1208.
rac-7,7-Bis(benzyloxy)-2,20-dihydroxy-1,10-binaphthyl
(rac-7). To a solution of 7-benzyloxy-2-naphthol (18 g,
72 mmol) in dichloromethane (100 mL) was added
CuCl(OH)´TMEDA (3.3 g, 14.2 mmol), and stirred under
the oxygen atmosphere until the reaction was complete.
The reaction mixture was washed with water and brine,
dried over MgSO4. After ®ltration, the volatile materials
were removed to give yellowish solids which were puri®ed
by passing on short-silica gel column (EtOAc/n-Hexaneˆ
1:4) to give pure rac-7 (16.3 g, 92%). Mp 105±1078C (lit.8a
104±1068C). All the spectral data were consistent with the
reported data.8a
(R)-7,7-Bis(tri¯uoromethanesulfonyloxy)-2,20-dimethoxy-
1,10-binaphthyl (10). To a solution of the diol 9 (4 g,
11.5 mmol) in anhydrous CH2Cl2 (40 mL) was added
Tf2O (8.2 g, 28.9 mmol) and pyridine (2.7 g, 34.6 mmol)
at 08C. The reaction mixture was stirred at 08C until all of
the diol 9 was consumed in TLC. After evaporation of the
solvent, the crude residue was puri®ed by column chroma-
tography on silica gel with 50% CH2Cl2 in ether to give 10
(6.14 g, 92%) as a white solid. Mp 1368C (sharply);
[a]2D5ˆ155.6 (c 1.02, CHCl3); 1H NMR (300 MHz,
CDCl3) d 8.04 (d, Jˆ9.1 Hz, 2H), 7.95 (d, Jˆ9.0 Hz, 2H),
7.52 (d, Jˆ9.1 Hz, 2H), 7.23 (dd, Jˆ2.2, 9.0 Hz, 2H), 6.98
(d, Jˆ2.2 Hz, 2H), 3.78 (s, 6H) ppm; 13C NMR (75.5 MHz,
CDCl3) d 156.38, 148.63, 134.53, 131.25, 130.59, 128.34,
121.20, 118.51, 117.52, 116.9, 114.90, 56.75 ppm;
HRMS(FAB1) Calcd for C24H16F6O8S2:610.0191. Found:
610.0186.
(R)-7,7-Bis(benzyloxy)-2,20-dihydroxy-1,10-binaphthyl
((R)-7). A mixture of quinine (18.1 g, 0.057 mol) and rac-7
(24.6 g, 0.049 mol) in ethanol (600 mL) was re¯uxed for
3 h. On cooling, precipitates were collected and dried to
give the (R)-7´quinine complex (15 g). Recrystallization
twice from ethanol (500 mL) yielded the pure complex
(14.9 g) which was dissolved in chloroform (300 mL) and
washed with 2 N HCl (3£250 mL). The aqueous layer was
extracted with chloroform. The combined organic layers
were washed with water, brine, dried with MgSO4. Evapo-
ration of the solvent afforded 9.8 g (40% based on rac-7) of
(R)-7. [a]2D5ˆ2232.8 (c 1.06, CHCl3) (lit.12 [a]2D1ˆ2232.0
(c 1.0, CHCl3)). To determine the optical purity, to a solu-
tion of (R)-7 (20 mg, 0.04 mmol) and MTPA (44 mg,
0.19 mmol) in dry CH2Cl2 (10 mL) were added DMAP
(20 mg, 0.164 mmol) and DCC (80 mg, 0.4 mmol). After
re¯uxing for 2 h, the mixture was cooled and the formed
dicyclohexylurea was removed by ®ltration. The solution
was diluted with CH2Cl2 and washed with H2O, 5%
(R)-7,7-Bis(aminobenzyl)-2,20-dimethoxy-1,10-binaphthyl
(11). To a mixture of Pd2(dba)3 (47 mg, 52 mmol), diphenyl-
phosphinoferrocene (94 mg, 0.17 mmol) and t-BuONa
(500 mg, 5.2 mmol) in toluene (50 mL) was added the
bis(tri¯ate) 10 (1 g, 1.73 mmol) and benzylamine
(0.57 mL, 5.2 mmol) at 08C. The reaction mixture was
stirred for 14 h at 908C and the reaction temperature was
allowed to cooled to 08C. After dilution with EtOAc
(100 mL), the organic layer was washed with 2% aqueous
HCl solution, water and brine, and dried over anhydrous
MgSO4, ®ltered and concentrated. The resulting residue
was puri®ed by column chromatography on silica-gel
(EtOAc/n-Hexaneˆ1:3) to give 11 (690 mg, 76% yield) as
a pale yellowish solid. Mp 78±808C; [a]2D5ˆ2385.5 (c 0.2,
CHCl3); 1H NMR (300 MHz, CDCl3) d 7.79 (d, Jˆ8.9 Hz,
2H), 7.67 (d, Jˆ7.7 Hz, 2H), 7.07±7.10 (m, 12H), 6.65 (dd,
Jˆ2.2, 9.0 Hz, 2H), 6.02 (d, Jˆ2.2 Hz, 2H), 3.99 (m, 4H),
3.59 (s, 6H) ppm; 13C NMR (75.5 MHz, CDCl3) d 155.88,
146.34, 139.78, 135.99, 129.38, 129.10, 128.83, 128.03,
127.33, 124.06, 118.61, 115.54, 110.75, 103.72, 57.18,
48.58 ppm; IR(KBr) 3412 (NH); HRMS(FAB1) Calcd for
C36H32N2O2: 524.2464. Found: 524.2463.
1
CH3CO2H, and brine. The H NMR (300 MHz, CDCl3)
spectrum of the crude Mosher's ester showed only one
a-OCH3 resonance signal at 2.97 ppm indicating that the
optical purity is of .99% ee.
(R)-7,7-Bis(benzyloxy)-2,20-dimethoxy-1,10-binaphthyl (8).
To a solution of the diol 7 (4.28 g, 8.6 mmol) in DMF
(40 mL) was added NaH (1.1 g, 21.5 mmol, 60% dispersed
in oil) at 08C, and the mixture was stirred for 1 h at room
temperature. After the reaction temperature was allowed to
cooled to 08C, iodomethane (4.9 g, 34.5 mmol) was added
slowly, and then stirred for overnight at room temperature.
The reaction mixture was diluted with CH2Cl2. After careful
addition of water at 08C, the organic layer was separated and
washed with 2% aqueous HCl solution, water and brine.
After evaporation of the solvent, the residue was puri®ed
by recrystallization from methanol to give pure 8 (4.52 g,
99%) as a white solid. Mp 129±1318C; [a]2D5ˆ2130.5 (c
0.2, CHCl3) (lit.8d Mp 126.5±1278C, [a]2D3ˆ2132 (c 1.28,
CHCl3)); 1H NMR (300 MHz, CDCl3) d 7.79 (d, Jˆ8.9 Hz,
2H), 7.67 (d, Jˆ7.7 Hz, 2H), 7.29 (d, Jˆ8.9 Hz, 2H)), 7.24±
7.14 (m, 10H), 7.10 (dd, Jˆ8.9, 2.5 Hz, 2H), 6.47 (d,
Jˆ2.5 Hz, 2H), 4.73 (bs, 4H), 3.69 (s, 6H) ppm; 13C NMR
(75.5 MHz, CDCl3) d 157.48, 155.86, 137.26, 135.52,
129.90, 129.40, 128.79, 128.10, 127.95, 125.30, 119.40,
117.07, 112.09, 105.49, 69.99, 57.13 ppm.
(R)-2,20-Bis[(N,N0-bis(o-diphenylphosphinobenzoyl))-
amino]-1,10-binaphthyl (3). A mixture of (R)-(1)-1,1-
binaphthyl-2,2-diamine (100 mg, 0.35 mmol), 2-(diphenyl-
phosphino)benzoic acid (270 mg, 0.88 mmol), DCC
(220 mg, 1.06 mmol) and DMAP (43 mg, 0.35 mmol) in
anhydrous CH2Cl2 (10 mL) was stirred until the starting
was completely consumed in TLC. The precipitates were
removed by ®ltration through the Celite, the ®ltrate was
(R)-7,70-Dihydroxy-2,20-dimethoxy)-1,10-binaphthyl (9).

C. W. Lim, S. Lee / Tetrahedron 56 (2000) 5131±5136
5135
washed with 2% HCl solution and water. After concen-
tration, the residue was puri®ed by silica-gel column chro-
matography to give 3 (180 mg, 59 %) as a white solid. Mp
134±1358C; [a]Dˆ126.0 (c 0.2, CHCl3); 1H NMR
(300 MHz, CDCl3) d 8.47 (d, Jˆ9.0 Hz, 2H), 7.96 (dd,
Jˆ9.0, 8.1 Hz, 4H), 7.70 (bs, 2H), 7.47 (t, Jˆ7.7 Hz, 2H),
7.04±7.36 (m, 28H), 6.81±6.88 (m, 4H) ppm; 13C NMR
(75.5 MHz, CDCl3) d 167.01, 140.52, 140.21, 137.49,
137.30, 137.25, 137.20, 137.15, 137.10, 135.23, 134.39,
133.89, 133.84, 133.63, 133.56, 132.37, 131.35, 130.45,
129.85, 128.73, 128.55, 128.39, 128.30, 127.37, 127.10,
127.04, 125.52, 125.33, 121.75, 120.90 ppm; 31P NMR
(121 MHz, CDCl3)24.56 ppm (triphenylphosphine as an
external standard); HRMS(FAB1) Calcd for C58H43
N2O2P2 [(M1H)1]: 861.2800. Found: 861.2791.
HRMS(FAB1) Calcd for C60H47N2O4P2 [(M1H)1]:
921.3031. Found: 921.3005.
(R)-6,6-Bis(benzylamino)-2,20-dimethoxy-1,10-binaphthyl
(14). To a mixture of Pd2(dba)3 (97 mg, 0.11 mmol), diphenyl-
phosphinoferrocene (120 mg, 0.21 mmol) and NaOt-Bu
(610 mg, 6.35 mmol) in toluene (50 mL) was added (R)-
6,60-dibromo-1,10-naphth-2-ol (1 g, 2.12 mmol) and benzyl-
amine (910 mg, 8.47 mmol) at 08C followed by stirred for
14 h at 908C. After the same workup as 11, the crude
product was puri®ed by column chromatography on silica-
gel (EtOAc/n-Hexaneˆ1:4) to give 14 (980 mg, 88%) as a
pale yellowish solid. Mp 85±878C; [a]2D5ˆ262.5 (c 0.2,
CHCl3); 1H NMR (300 MHz, CDCl3) d 7.68 (d, Jˆ
9.0 Hz, 2H), 7.23±7.41 (m, 12H), 6.95 (d, Jˆ9.0 Hz, 2H),
6.86 (d, Jˆ2.3 Hz, 2H), 6.60 (dd, Jˆ9.0, 2.3 Hz, 2H), 4.37
(s, 4H), 3.96 (bs, 2H), 3.67 (s, 6H) ppm; 13C NMR
(75.5 MHz, CDCl3) d 153.02, 144.56, 139.86, 131.23,
129.06, 128.50, 128.08, 127.66, 127.51, 127.03, 121.00,
119.01, 115.74, 105.23, 57.78, 48.98 ppm; HRMS(FAB1)
Calcd for C36H32N2O2: 524.2464. Found: 524.2462.
(R)-7,70-Bis[(O,O0-bis(o-diphenylphosphinobenzoyl))hy-
droxy]-2,20-dimethoxy-1,10-binaphthyl (4). A solution of
2-(diphenylphosphino)benzoic acid (500 mg, 2 mmol),
DCC (530 mg, 2.6 mmol) and DMAP (100 mg,
0.78 mmol) in anhydrous CH2Cl2 (20 mL) was stirred for
1 h, and then the diol 9 (300 mg, 0.87 mmol) was added at
room temperature. After stirring until all of the diol 9 was
consumed, the precipitates were removed through the
Celite, the ®ltrate was washed with 2% aqueous HCl solu-
tion and water. After concentration, the residue was puri®ed
by silica-gel column chromatography to give 4 (540 mg,
68%) as a white solid. Mp 202±2038C; [a]2D5ˆ281.6 (c
(R)-(2)-6,60-Bis[(N,N0-bis(o-diphenylphosphinobenzoyl))-
amino]-2,20-dimethoxy-1,10-binaphthyl (6). A mixture of
900 mg (1.72 mmol) dibenzyl 14 and catalytic amount of
Pd/C in methanol (20 mL) was stirred under the hydrogen
atmosphere (1 atm) for overnight afforded diamine 15
(620 mg, 95%) as a yellowish solid which used for the
next reaction without puri®cation. A solution of 2-(diphenyl-
phosphino)benzoic acid (500 mg, 2mmol), DCC (530 mg,
2.6 mmol) and DMAP (100 mg, 0.78 mmol) in anhydrous
CH2Cl2 (20 mL) was stirred for 1 h. To this solution was
added diamine 15 (300 mg, 0.87 mmol) at room tempera-
ture. The reaction mixture was further stirred during over-
night. After ®ltration of the precipitate formed, the volitiles
were removed under reduced pressure and the residue was
puri®ed by column chromatography to give 6 (600 mg,
75%) as a pale yellowish solid. Mp 181±1838C; [a]2D5260
(c 0.2, CHCl3); 1H NMR (300 MHz, CDCl3) d 8.20 (bs, 2H),
7,86 (d, Jˆ9.0 Hz, 2H), 7.73±7.74 (m, 4H), 7.68 (d, Jˆ
2.1 Hz, 2H), 7.23±7.43 (m, 26H), 6.98±7.02 (m, 2H), 6.92
(d, Jˆ9.0 Hz, 2H), 6.66 (dd, Jˆ9.0, 2.1 Hz, 2H), 3.73 (s,
6H) ppm; 13C NMR (75.5 MHz, CDCl3) d 167.61, 154.90,
142.55, 142.19, 136.90, 136.76, 134,53, 134.27, 133.36,
131.73, 130.87, 129.79, 129.72, 129.54, 129.48, 129.24,
129.17, 128.95, 128.88, 126.36, 120.87, 117.78, 115.24,
57.31 ppm; 31P NMR (121 MHz, CDCl3) 25.92 ppm (tri-
phenylphosphine as an external standard); HRMS(FAB1)
Calcd for C60H47N2O4P2 [(M1H)1]: 921.3031. Found:
921.3005.
1
0.2, CHCl3); H NMR (300 MHz, CDCl3) d 8.15 (m, 2H),
7.85 (d, Jˆ9.1 Hz, 2H), 7.77 (d, Jˆ9.0 Hz, 2H), 7.17±7.38
(m, 26H), 6.92±6.95 (m, 4H), 6.74 (bs, 2H), 3.64 (s, 6H)
ppm; 13C NMR (75.5 MHz, CDCl3) d 165.58, 155.77,
141.55, 138.01, 135.01, 134.62, 134.54, 134.50, 134.26,
134.22, 132.73, 131.78, 129.76, 129.61, 129.04, 129.00,
128.88, 128.78, 128.56, 127.62, 119.46, 116.37, 114.11,
57.06 ppm; 31P NMR (121 MHz, CDCl3) 21.17 ppm
(triphenylphosphine as an external standard); IR(KBr)
1732 (CvO) cm21; HRMS(FAB1) Calcd for C60H45O6P2
[(M1H)1]: 923.2691. Found: 923.2694.
(R)-7,70-Bis[(N,N0-bis(o-diphenylphosphinobenzoyl))-
amino]-2,20-dimethoxy-1,10-binaphthyl (5). A mixture of
N,N0-dibenzylamine 11 (4.52 g, 8.6 mmol) and catalytic
amount of Pd/C in methanol (100 mL) was stirred under
the hydrogen atmosphere (1 atm) during overnight and
®ltered through Celite to removed the catalyst, and then
concentrated
to
give
(R)-(2)-7,7-bis(amino)-2,20-
dimethoxy-1,10-binaphthyl 12 (2.73 g, 91%) as a yellowish
solid which used for the next reaction without further puri-
®cation. DCC coupling of the diamine 12 (300 mg,
0.87 mmol) with 2-(diphenylphosphino)benzoic acid
(500 mg, 2 mmol) under the same reaction conditions as 3
afforded 5 (540 mg, 68%) as a white solid. Mp 157±1588C;
[a]2D5ˆ2161.5 (c 0.2, CHCl3); 1H NMR (300 MHz, CDCl3)
d 7.91 (d, Jˆ8.99 Hz, 2H), 7.76±7.82 (m, 4H), 7.60 (m,
2H), 7.50 (bs, 2H), 7.13±7.38 (m, 28H), 6.92±6.96 (m,
2H), 6.65 (bs, 2H), 3.74 (s, 6H) ppm; 13C NMR
(75.5 MHz, CDCl3) d 167.46, 155.77, 141.99, 141.65,
136.95, 136.81, 136.72, 136.51, 134.66, 134.45, 134.28,
134.18, 130.77, 129.67, 129.30, 129.23, 129.02, 128.93,
128.66, 127.24, 119.03, 118.80, 114.45, 113.70,
57.23 ppm; 31P NMR (121 MHz, CDCl3) 24.93 ppm
General procedure for Pd(0)-catalyzed desymmetri-
zation of bis(carbamate) 16
To a solution of bis(carbamate) 16 (0.5 mmol) in THF
(0.5 mL) was added a solution of Pd2(dba)3´CHCl3
(12.5 mmol) and bisphosphine ligand (37.4 mmol) in THF
(0.8 mL) at 08C. The reaction mixture was degassed and
stirred at 208C for 14 h. After evaporation of the solvent,
the residue was puri®ed by preparative TLC (EtOAc/petro-
leum etherˆ1:2) to give a mixture of oxazolidinones 17 and
ent-17. Enantiomeric excess has been determined by HPLC
using Chiralpak AD chiral column (eluent: for 17a and 17b,
(triphenylphosphine
as
an
external
standard);

5136
C. W. Lim, S. Lee / Tetrahedron 56 (2000) 5131±5136
8. (a) Hester, M. R.; Uyeki, M. A.; Diederich, F. Israel J. Chem.
1989, 29, 201. (b) Martinborough, E.; Denti, T. M.; Castro, P. P.;
Wyman, T. B.; Knobler, C. B.; Diederich, F. Helv. Chim. Acta
1995, 78, 1037. (c) Anderson, S.; Neidlein, U.; Gramlich, V.;
Diederich, F. Angew, Chem. Int. Ed. Engl. 1995, 34, 1596. (d)
Horiuchi, T.; Ohta, T.; Stephan, M.; Takaya, H. Tetrahedron:
Asymmetry 1994, 5, 325.
heptane:isopropanolˆ85:15, for 17c heptane:isopropanolˆ
30:70, ¯ow rate: 1 mL/min).5h Retention time (min): 17a
(33.95), ent-17a (29.79); 17b (45.28), ent-17b (36.94); 17c
(19.40), ent-17c (15.79). The results are listed in Table 1.
Acknowledgements
9. Oxidative coupling of naphthol, see: (a) Feringa, B.; Wynberg,
H. Tetrahedron Lett. 1977, 4447. (b) Feringa, B.; Wynberg, H.
J. Org. Chem. 1981, 46, 2547. (c) Toda, F.; Tanaka, K.; Iwata,
We are grateful to the Korea Institute of Science and Tech-
nology (2v00363 and 2v00443) and, in part, Korea Fine
Chemical, Inc. (2M08371) for support of this work.
Â
S. J. Org. Chem. 1989, 54, 3007. (d) Hovorkova, M.; GuÈnterova, J.;
Â
Zavada, J. Tetrahedron Lett. 1990, 31, 413. (e) Smrcina, M.;
Ï
Lorenc, M.; Hanus, V.; Kocovsku, P. Synlett 1991, 231. (e)
Â
Ï
Â
Smrcina, M.; Lorenc, M.; Hanus, V.; Sedmera, P.; Kocovsku, P.
J. Org. Chem. 1992, 57, 1917.
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È