Non-C2-symmetrical antimony-phosphorus ligand, (R/S)-2-diphenylphosphano-2′-di(p-tolyl)stibano-1,1′-binaphthyl (BINAPSb): Preparation and its use for asymmetric reactions as a chiral auxiliary

Article abstract of DOI:10.1016/j.tetlet.2004.10.020

A new non-C₂-symmetrical antimony-phosphorous ligand, (±)-2-diphenyl-phosphano-2′-di(p-tolyl)stibano-1, 1′-binaphthyl (BINAPSb) 3, has been prepared from 2-bromo-2′- diphenylphosphano-1,1′-naphthyl 4 via its borane complex 6, and could be resolved by the separation of a mixture of the diastereomeric palladium complexes 8A and 8B derived from the reaction of (±)-3 with optically active palladium reagent (S)-7. The enantiomerically pure BINAPSb 3 has proved to be highly effective in the palladium-catalyzed asymmetric hydrosilylation of styrene as a chiral auxiliary.

Full text of DOI:10.1016/j.tetlet.2004.10.020

Tetrahedron
Letters
Tetrahedron Letters 45 (2004± 9135–9138
Non-C -symmetrical antimony–phosphorus ligand,
2
0
0
(
R/S)-2-diphenylphosphano-2 -di(p-tolyl)stibano-1,1 -binaphthyl
(
BINAPSb): preparation and its use for asymmetric
reactions as a chiral auxiliary
a
a
a
Shuji Yasuike, Shin-ichiro Kawara, Satoru Okajima, Hiroko Seki,
b
c
Kentaro Yamaguchi and Jyoji Kurita
a,
*
a
Faculty of Pharmaceutical Sciences, Hokuriku University, Kanagawa-machi, Kanazawa 920-1181, Japan
b
Chemical Analysis Center, Chiba University, 1-33 Yayoicho, Inage-ku, Chiba 263-8522, Japan
Faculty of Pharmaceutical Sciences at Kagawa Campus, Tokushima Bunri University, Shido, Sanuki-city, Kagawa 769-2193, Japan
c
Received 30 August 2004; revised 30 September 2004; accepted 1 October 2004
Available online 22 October 2004
0
0
Abstract—A new non-C -symmetrical antimony–phosphorous ligand, (± ±-2-diphenyl-phosphano-2 -di(p-tolyl±stibano-1,1 -binaph-
2
0
0
thyl (BINAPSb± 3, has been prepared from 2-bromo-2 -diphenylphosphano-1,1 -naphthyl 4 via its borane complex 6, and could be
resolved by the separation of a mixture of the diastereomeric palladium complexes 8A and 8B derived from the reaction of (± ±-3 with
optically active palladium reagent (S±-7. The enantiomerically pure BINAPSb 3 has proved to be highly effective in the palladium-
catalyzed asymmetric hydrosilylation of styrene as a chiral auxiliary.
ꢀ
2004 Elsevier Ltd. All rights reserved.
Catalytic asymmetric synthesis using transition metal
0
0
2
complexes with chiral 2,2 -substituted-1,1 -binaphthyl
ligands is a powerful and economically promising
method for the synthesis of enantiomerically enriched
1
1
2
8
a
R
R
8a'
1'
2'
1
compounds. Among them, the most useful chiral ligand
0
is phosphorus compounds such as 2,2 -bis(diphenyl-
0
1
2
1: R = R = PPh2
phosphano±-1,1 -binaphthyl (BINAP± 1, which exhibit
high enantioselectivity in various types of asymmetric
1
2
2
3
: R = R = Sb(p-Tol)2
1
2
: R = PPh2, R = Sb(p-Tol)2
1
,2
reactions. Taking advantage of the marked efficiency
0
of the 1,1 -binaphthyl core as a chiral inducer, a variety
0
Figure 1.
of hetero-bidentate 1,1 -binaphthyls bearing one phos-
phorous and one other heteroatom group such as nitro-
3
4
5
6
0
7
gen, arsenic, oxygen and sulfur on the 2,2 -positions
0
these were derived from optically active BINAP. In the
course of our current studies on organoantimony com-
pounds, we are interested in the synthesis and utilization
of optically active organoantimony compounds for
asymmetric reaction as a chiral auxiliary. As a part of
our research, we have recently reported the synthesis
of the 1,1 -binaphthyl backbone have been developed
and employed successfully in a wide range of enantiose-
lective reactions, during the last two decades. Recently,
0
8
a versatile synthesis of optically active 2 -substituted 2-
0
phosphano-1,1 -binaphthyls containing group 14 (sili-
con, tin± and 17 (iodine± elements was attained, although
of an enantiomerically pure C -symmetrical antimony–
2
0
0
antimony ligand, 2,2 -bis(diarylstibano±-1,1 -binaphthyl
BINASb± 2, and its efficiency for palladium-catal-
yzed asymmetric allylic alkylation of racemic 1,3-di-
phenyl-2-propen-1-yl acetate as a chiral inducer.
We present here the synthesis and resolution of a new
(
Keywords: Antimony and compounds; Resolution; Asymmetric reac-
tion; Palladium and compounds; Hydrosilylation.
9
*
Corresponding author. Tel.: +81 76 229 1165; fax: +81 76 229
781; e-mail: j-kurita@hokuriku-u.ac.jp
2
non-C -symmetrical antimony–phosphorous ligand,
2
0
040-4039/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2004.10.020

9136
S. Yasuike et al. / Tetrahedron Letters 45 (2004) 9135–9138
BH3
ii, iii
iv
M
PPh2
PPh2
Br
Sb(p-Tol)2
Sb(p-Tol)2
4
5
: M = PPh2
BH3
6
(±)-3
i
: M = PPh2
Me2
Me
N
v
+
Pd
2
Me2
N
Ph2
P
Cl
S)-7
Me
vi
(R)-(-)-3
(
-
Cl
Pd
(
S)-(+)-3
Sb
(
p-Tol)2
(
(
S, S)-8A
S, R)-8B
Scheme 1. Reagents and conditions: (i± BH
3
–THF, THF, 0ꢁC, 1h, 98%; (ii± n-butyllithium, THF, À80ꢁC, 1h; (iii± (p-Tol±
2
SbBr, THF, À80ꢁC to
0ꢁC, 2h, 58%; (iv± diethylamine, THF, 40ꢁC, 1h, 91%; (v± dichloromethane, room temperature, 30min, 94%; (vi± triphenylphosphine,
dichloromethane, room temperature, 30min, 85–91%.
0
0
2
-diphenylphosphano-2 -di(p-tolyl±-stibano-1,1 -binaph-
acetate/dichloromethane/ethanol (8:4:1± as an eluent.
Thus, the palladium complexes (–±-8A and (+±-8B were
obtained in 84% and 99% yields, respectively. The struc-
tures of 8A and 8B were elucidated mainly by their
MS(FAB±, NMR spectral and elemental analyses. The
palladium complexes 8A and 8B are presumed to be a
cationic salt structure by the following evidence. The
R values on TLC (AcOEt/CH Cl /EtOH = 8:4:1± for
8A (0.49± and 8B (0.17± are similar to those for BI-
NAP-(S±-7 complexes [0.10 for (+±-BINAP-(S±-7 and
0.09 for (–±-BINAP-(S±-7], and are largely different from
those of BINASb-(S±-7 complexes [0.95 for (+±-BIN-
ASb-(S±-7 and 0.91 for (–±-BINASb-(S±-7] which have
been known to be a nonsalt structure. Diastereomeric
thyl (BINAPSb± 3, as well as its usefulness for palla-
dium-catalyzed asymmetric hydrosilylation of styrene
as a chiral auxiliary.
First, introduction of a di(p-tolyl±antimony group at
0
0
the 2 -position on the 2-diphenylphosphano-1,1 -
binaphthyl core was performed by a straightforward
f
2
2
0
procedure including lithiation of 2-bromo-2 -diphenyl-
10
0
phosphano-1,1 -binaphthyl 4 with n-butyllithium and
subsequent trapping with bromodi(p-tolyl±stibane [(p-
Tol± SbBr] at low temperature (À80ꢁC±. However, this
2
direct metal insertion reaction on 4 produced the
expected BINAPSb 3 in low yield (<8%±, probably due
to the instability of the lithio intermediate and/or
carbon–phosphorus bond cleavage with n-butyllithium.
This result led us to attempt a modern metallation path-
way including a phosphorous-borane complex devel-
7
oped by Hayashi and co-workers. The borane
complex 5 was readily prepared from 4 by treatment
1
1
with borane in THF. The transformation of 5 into BI-
NAPSb-borane complex 6 could be achieved by lithi-
ation with n-butyllithium at À80ꢁC followed by
reaction with (p-Tol± SbBr in 58% yield, presumably
2
0
via a stable 2 -lithio binaphthyl intermediate. The bor-
Sb
P
ane complex 6 underwent ligand exchange reaction
upon treatment with diethylamine to yield (± ±-BI-
NAPSb 3 in 90% yield. According to this procedure,
± ±-3 was obtained in more than 50% overall yield from
(Scheme 1±.
(
4
Next, we attempted the resolution of (± ±-3 via their dia-
stereomeric complexes using optically active palladium
reagent, di-l-chlorobis[(S±-dimethyl(1-ethyl-a-naphth-
2
yl±aminato-C ,N]dipalladium(II± (S±-7, which have been
reported to be a useful resolving agent for antimony
a,b,d
8
compounds.
The reaction of (± ±-3 with (S±-7
afforded an equimolar amount of a diastereomeric
mixture of 8A and 8B, which could be separated by silica
gel column chromatography by use of a mixture of ethyl
˚
Figure 2. Molecular structure of (S±-(–±-3. Selected bond distances (A±
0
0
and angles (ꢁ±: C(1±–C(1 ± 1.500(8±, C(2±–P 1.841(6±, C(2 ±–Sb 2.148(6±,
C(2±–C(1±–C(1 ±–C(2 ± 69.9(8±, C(8a±–C(1±–C(1 ±–C(8a ± 72.3(7±.
0
0
0
0

S. Yasuike et al. / Tetrahedron Letters 45 (2004) 9135–9138
9137
(
R)-BINAPSb 4 (0.2 mol%)
Pd(C3H5)Cl]2
HSiCl3
SiCl3
OH
[
1
2
) KF / MeOH
) H2O2 / DMF
9
10
11
Scheme 2.
3
1
purity of 8A and 8B was determined by the P NMR
Acknowledgements
3
1
spectra in that each P signal appeared at 47.8ppm
for 8A and 46.3ppm for 8B. Treatment of 8A and 8B
with triphenylphosphine brought about ligand exchange
reaction to afford optically pure (+±-3 and (–±-3, respec-
Partial financial support for this work was provided by a
Grant-in Aid for Scientific Research from the Ministry
Education, Sciences, Sports and Culture of Japan, and
Takeda Scientific Foundation. Financial support by
the Specific Research Fund from Hokuriku University
was also gratefully acknowledged.
1
2
tively, in excellent yields. Single-crystal X-ray analysis
1
3
of (–±-3 revealed that (–±-3 is S-configuration (Fig. 1±,
and the dihedral angle of the two naphthalene rings
0
0
[
C(8a±–C(1±–C(1 ±–C(8a ± = 72.3ꢁ] is smaller than that
8b
of (R±-BINASb (90ꢁ± (Fig. 2±.
References and notes
We examined the ability of optically active BINAPSb 3
as a ligand in palladium-catalyzed asymmetric allylic
1
2
. (a± Rosini, C.; Franzini, L.; Raffaelli, A.; Salvadoria, P.
Synthesis 1992, 503–517; (b± McCarthy, M.; Guiry, P. J.
Tetrahedron 2001, 57, 3809–3844; (c± Ko cˇ ovsk y´ , P.;
Vysko cˇ il, S.; Smr cˇ ina, M. Chem. Rev. 2003, 103, 3213–
3
. For recent reviews, see: (a± Ohkuma, T.; Kitamura, M.;
Noyori, R. In Catalytic Asymmetric Synthesis; Ojima, I.,
Ed., 2nd ed.; Wiley-VCH: New York, 2000; pp 1–110; (b±
Akutagawa, S.; Tani, K. In Catalytic Asymmetric Syn-
thesis; Ojima, I., Ed., 2nd ed.; Wiley-VCH: New York,
1
4
15
alkylation and asymmetric hydrosilylation. The reac-
tion of (± ±-1,3-diphenyl-2-propen-1-yl acetate with
dimethyl malonate by use of BSA, [Pd(C H ±Cl] , (R±-
ˇ
3
5
2
245.
BINAPSb 3A and AcOK (acetate:malonate:BSA:Pd
cat.:ligand:AcOK = 1:3:3:0.02:0.04:0.02± in dichloro-
methane over 24h at room temperature afforded (S±-
dimethyl(1,3-diphenylprop-2-en-1-yl±malonate in 30%
yield with 45% ee. The result shows that the reaction
rate and enantioselectivity with BINAPSb 3 were both
lower compared to those with BINASb 2 (68%, 81%
2
(
000, pp 145–161; (c± Hayashi, T. Synlett 2001, 879–887;
d± Noyori, R. Angew. Chem., Int. Ed. 2002, 41, 2008–
2022; (e± Hayashi, T.; Yamazaki, K. Chem. Rev. 2003, 103,
829–2844.
9
ee± (Scheme 2±.
2
1
5
ˇ
The asymmetric hydrosilylation of styrene with tricho-
rosilane was carried out at 0ꢁC without a solvent in the
presence of 0.2mol% of the palladium catalyst generated
in situ by mixing [Pd(C H ±Cl] with 2equiv (to Pd±
3. For examples, see: (a± Vysko cˇ i, S.; Smr cˇ ina, M.; Hanu sˇ ,
V.; Pol a´ sˇ ek, M.; Ko cˇ ovsk y´ , P. J. Org. Chem. 1998, 63,
7738–7748; (b± Lloyd-Jones, G. C.; Stephen, S. C.;
ˇ
Murray, M.; Butts, C. P.; Vysko cˇ i, S.; Ko cˇ ovsk y´ , P.
Chem. Eur. J. 2000, 6, 4348–4357; (c± Chieffi, A.; Kami-
˚
kawa, K.; Ahman, J.; Fox, J. M.; Buchwald, S. L. Org.
Lett. 2001, 3, 1897–1900; (d± Hamada, T.; Buchwald, S. L.
Org. Lett. 2002, 4, 999–1001.
3
5
2
of the (R±-BINAPSb 3A: (styrene:trichorosilane:[Pd-
C H ±Cl] :ligand = 1000:1200:1:2±. The hydrosilylation
product, 1-trichlorosilyl-1-phenyl-ethane 10, initially
(
3
5
2
formed was oxidized to optically active 1-phenylethanol
1
4
5
6
. (a± Kojima, A.; Boden, C. D. J.; Shibasaki, M. Tetrahe-
dron Lett. 1997, 38, 3459–3460; (b± Miyazaki, F.; Uotsu,
K.; Shibadaki, M. Tetrahedron 1998, 54, 13073–
13078.
. For reviews, see: (a± Hayashi, T. Acta Chem. Scand. 1996,
50, 259–266; (b± Hayashi, T. J. Organomet. Chem. 1999,
1 by hydrogen peroxide in the presence of potassium
1
6
fluoride. Thus, (R±-11 was obtained in good yield
78% yield± with high enantioselectivity (95% ee±, when
the reaction was carried out at 0ꢁC for 10h with (R±-BI-
(
1
7
NAPSb 3. Neither noticeable catalytic activity nor
perceptible enantioselectivity was observed when (R±-
BINASb 2 was employed instead of (R±-BINAPSb 3A
in the present reaction (0ꢁC, 24h, 10% yield, 12% ee±.
These results suggest that BINAPSb 3 has similar ability
to H-MOP and was proved to be a more powerful ligand
5
3
76, 195–202; (c± Hayashi, T. Acc. Chem. Res. 2000, 33,
54–362; (d± Hayashi, T. Catal. Today 2000, 63, 3–15.
. (a± Gladiali, S.; Dore, A.; Fabbri, D. Tetrahedron:
Asymmetry 1994, 5, 1143–1146; (b± Gladiali, S.; Medici,
S.; Pirri, G.; Pulacchini, S.; Fabbri, D. Can. J. Chem. 2001,
79, 670–678.
7. Shimada, T.; Kurushima, H.; Cho, Y.-h.; Hayashi, T.
J. Org. Chem. 2001, 66, 8854–8858.
0
6
0
than other 2 -heteroatom substituted 2-phosphano-1,1 -
b,15
binaphthyls.
8
. (a± Kurita, J.; Usuda, F.; Yasuike, S.; Tsuchiya, T.; Tsuda,
Y.; Kiuchi, F.; Hosoi, S. Chem. Commun. 2000, 191–192;
(b± Yasuike, S.; Okajima, S.; Yamaguchi, K.; Seki, H.;
Kurita, J. Tetrahedron: Asymmetry 2000, 11, 4043–4047;
Consequently, we have accomplished the synthesis of
0
optically active 2 -antimony substituted 2-phosphano-
0
1,1 -binaphthyl derivative BINAPSb, and demonstrated
that this non-C -symmetrical antimony–phosphorous
(
c± Okajima, S.; Yasuike, S.; Kakusawa, N.; Osada, A.;
Yamaguchi, K.; Seki, H.; Kurita, J. J. Organomet. Chem.
002, 656, 234–242; (d± Yasuike, S.; Okajima, S.; Yama-
guchi, K.; Seki, H.; Kurita, J. Tetrahedron 2003, 59, 4959–
966.
2
binaphthyl system should be useful for the enantioselec-
tive hydrosilylation of styrene with trichorosilane.
Details of this reaction as well as further application
of the optically active BINAPSb to other asymmetric
reactions are now in progress.
2
4
9. Yasuike, S.; Okajima, S.; Yamaguchi, K.; Seki, H.;
Kurita, J. Tetrahedron Lett. 2003, 44, 6217–6220.

9138
S. Yasuike et al. / Tetrahedron Letters 45 (2004) 9135–9138
1
1
1
0. Gladiali, S.; Dore, A.; Fabbri, D.; Medici, S.; Pirri, G.;
1993, 4, 2419–2422; (b± Kitayama, K.; Uozumi, Y.;
Hayashi, T. J. Chem. Soc., Chem. Commun. 1995, 1533–
1534; (c± Gladiali, S.; Pulacchini, S.; Fabbri, D.; Manass-
ero, M.; Sansoni, M. Tetrahedron: Asymmetry 1998, 9,
391–395; (d± Hayashi, T.; Hirata, S.; Kitayama, K.; Tsuji,
H.; Torii, A.; Uozumi, Y. Chem. Lett. 2000, 1272–1273;
(e± Hayashi, T.; Hirata, S.; Kitayama, K.; Tsuji, H.; Torii,
A.; Uozumi, Y. J. Org. Chem. 2001, 66, 1441–1449; (f±
Jensen, J. F.; Svendsen, B. Y.; la Cour, T. V.; Pedersen, H.
L.; Johannsen, M. J. Am. Chem. Soc. 2002, 124, 4558–
4559.
Pulacchini, S. Eur. J. Org. Chem. 2000, 2861–2865.
1. Imamoto, T.; Kusumoto, T.; Suzuki, N.; Sato, K. J. Am.
Chem. Soc. 1985, 107, 5301–5301.
2. Selected physical and spectral data for (S±-(–±-3: mp
2
D
4
1
1
(
70–174ꢁC, ½aŠ À 23:8ꢁ (c 1.0, benzene±, H NMR
500MHz, JHz, CDCl ±: d 2.27 (3H, s±, 2.30(3H, s±,
3
6
7
8
8
.85 (1H, d, J 8.2±, 6.92–7.25 (21H, m± 7.30(1H, t, J 6.9±,
.37 (1H, t, J 6.9±, 7.42 (1H, dd, J 3.2, 8.7±, 7.58 (1H, d, J
.7±, 7.79 (1H, d, J 7.8±, 7.80(1H, d, J 8.2±, 7.84 (1H, d, J
3
1
3
.2±, 7.91 (1H, d, J 8.7±; P NMR (202.4MHz, CDCl ±: d
+
À15.2; m/z (FAB± 741 [M + H] . For (R±-(+±-3: mp
16. (a± Tamao, K.; Ishida, N.; Tanaka, T.; Kumada, M.
Organometallics 1983, 2, 1694–1696; (b± Pioda, G.; Togni,
A. Tetrahedron: Asymmetry 1998, 9, 3903–3910.
2
4
1
1
73–176ꢁC, ½aŠ þ 24ꢁ (c 1.03, benzene±. The H and
D
P NMR spectra of (R±-3 were superimposable to those of
3
1
+
S±-3; m/z (FAB± 741 [M + H] .
(
3. Crystal data for (S±-3: C46
3 5 2
17. Typical experiment: To a mixture of [Pd(C H ±Cl]
1
H36PSb, M = 741.51, tetragonal,
a = 9.468(1±, c = 39.759(7± A, V = 3563.8(9± A ,
(3.66mg, 0.01mmol±, (R±-BINAPSb 3A (14.8mg,
0.02mmol± and styrene (1.1ml, 10mmol± was added
trichlorosilane (1.2ml, 12mmol± at 0ꢁC, and the reaction
mixture was stirred for 10h at room temperature. The
reaction mixture was carefully poured into a suspension of
KF (10g± in methanol (80ml± and stirred for 30min. After
removal of the solvent in vacuo, the resulting solid was
˚
˚
3
T = 100K, space group P4 (no.76±, Z = 4, l(MoKa± =
1
À1
8
.5cm , 21632 reflections measured, 5894 reflections
[
I > 2.00r(I±, 2h < 57.33ꢁ] were used in all calculation,
R = 0.070, R = 0.091. The structure was solved by direct
w
methods and expanded using Fourier techniques. The
nonhydrogen atoms were refined anisotropically. Full
details of the crystallographic results have been deposited
with the Cambridge Crystallographic Data Centre [No.
CCDC 252378].
2 2 2
suspended in DMF (100ml± and H O (10ml, 30% H O
solution±, and then the mixture was heated for 1h at 65ꢁC.
The mixture was diluted with CH Cl (100ml± and water
(100ml±. The organic layers were separated and the
aqueous layer was extracted with CH Cl
2
2
1
4. (a± For reviews including transition metal-catalyzed asym-
metric allylic substitution, see Trost, B. M.; Lee, C. In
Catalytic Asymmetric Synthesis; Ojima, I., Ed., 2nd ed.;
Wiley-VCH: New York, 2000; pp 593–649; (b± Sawamura,
M.; Ito, Y. Chem. Rev. 1992, 92, 857–871; (c± Frost, C. G.;
Howarth, J.; Williams, J. M. J. Tetrahedron: Asymmetry
2
2
(50ml · 2±.
The combined organic layer was washed with water
(100ml · 5±, dried, and evaporated in vacuo. The residue
was separated by column chromatography on silica gel
2 2
with CH Cl /AcOEt (10:1± to give (R±-1-phenylethanol 11
(0.91g, 78% yield±. The absolute configuration (R± and the
enantiomeric excess (95% ee± of the product obtained here
were determined by chiral HPLC using commercially
available (R±- and (S±-1-phenylethanols as an authentic
sample [Daicel Chiral OD-H column; eluent, n-heptane:
1992, 3, 1089–1122; (d± Trost, B. M.; Vranken, D. L. V.
Chem. Rev. 1996, 96, 395–422; (e± Trost, B. M. Chem.
Pharm. Bull. 2002, 50, 1–14.
5. For palladium-catalyzed asymmetric hydrosilylation of
1
0
styrene with 1,1 -binaphthyl derivatives, see: (a± Uozumi,
Y.; Kitayama, K.; Hayashi, T. Tetrahedron: Asymmetry
i-PrOH = 95:5; retention times,
15.4min].
t
R
= 13.6min,
S
t =