A concise synthesis of 2-diarylphosphino-2′-methoxy-1,1′- binaphthalenes (MOPs) by simple resolution

Article abstract of DOI:10.1016/j.tetasy.2003.10.034

A practical synthesis of 2-diarylphosphino-2′-methoxy-1,1′- binaphthalene (MOPs) was provided by employing the etherification of 1,1′-bi-2,2′-naphthol on zeolite; the ring opening of the ether with lithium; the reaction with chlorodiaryl phosphine and the

Full text of DOI:10.1016/j.tetasy.2003.10.034

Tetrahedron:
Asymmetry
Tetrahedron: Asymmetry 15 (2004) 17–19
A concise synthesis of 2-diarylphosphino-20-methoxy-1,10-
binaphthalenes (MOPs) by simple resolution
Yunfei Luo, Feng Wang, Gangguo Zhu and Zhaoguo Zhang*
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Road, Shanghai 200032, China
Received 27 September 2003;accepted 21 October 2003
Abstract—A practical synthesis of 2-diarylphosphino-20-methoxy-1,10-binaphthalene (MOPs) was provided by employing the
etherification of 1,10-bi-2,20-naphthol on zeolite;the ring opening of the ether with lithium;the reaction with chlorodiaryl phosphine
and the resolution with (1S)-(+)-10-camphorsulfonyl chloride as the key steps.
Ó 2003 Elsevier Ltd. All rights reserved.
To develop new chiral ligands that might realize high
enantioselectivity in asymmetric catalytic reactions is an
important area in current research. Based on the chiral
involves a nucleophilic aromatic substitution reaction
of 1-methoxy-2-(diphenylphosphino)naphthalene with
Grignard reagent. However, the monophosphine ligands
made by this method were racemic.
structure of 1,10-binaphthalenyl-2,20-diol,
a
chiral
monophosphine ligand 20-diphenylphosphanyl-1,10-
binaphthalenyl-2-ol was reported by Morgans and
co-workers.1 Later, Hayashi and co-workers2 reported
an improved synthesis enroute to substituted chiral
monophosphine ligands (MOPs) that are efficient for
several types of palladium-catalyzed asymmetric reac-
tions including asymmetric hydrosilylation of olefins,3
asymmetric 1,4-hydroboration of 1,3-enynes to form
allenyl boranes,4 and asymmetric reduction of allylic
esters with formic acid.5 In these reactions, the use of
MOP-type ligands is crucial for obtaining high catalytic
reactivity and regioselectivity as well as high enantiose-
lectivity. Moreover, once the parent structure of chiral
MOP-type ligands was established, it was expanded into
other useful ligands, such as PHEST,6 BINAPHOS,7
BIPPHOS,7 BIPNITE7 etc., which now have been uti-
lized in Pd-catalyzed asymmetric allylic substitution,6a
Rh-catalyzed highly enantioselective hydroformylation
of olefins.7 Besides that the hydroxy group can also be
converted into the thiol to produce another bidentate
Heinicke and co-workers10 reported a facile route to
synthesize biaryl racemic monophosphine ligands from
either dibenzofuran or dinaphthofuran by lithium-
mediated ring opening and a subsequent reaction with
chlorodiphenylphosphine. However, attempts to resolve
the racemic 20-diphenylphosphinoyl-1,10-binaphthal-
enyl-2-ol with camphorsulfonyl chloride failed, with
only oxidized product being obtained.
It could be envisioned that the oxidized product could
undergo further reaction with a chiral acid to form an
ester, and the pair of diastereoisomers would have sig-
nificantly different physical properties that would let
them be separated from each other.
According to the literature procedure,10 we prepared the
dinaphthofuran in high yield by employing HY zeolite
with a SiO2/Al2O3 ratio of about 14. The ring opening of
the dinaphthofuran with lithium at rt in Et2O afforded
the intermediate dilithium salt 3. The dilithium salt 3
was then quenched with chlorodiphenyl phosphine
oxide instead of chlorodiphenyl phosphine to give the
racemic hydroxy phosphine oxide 4, which served as the
precursor to be resolved (Scheme 1).
ligand
thiol.8
20-diphenylphosphanyl-1,10-binaphthalenyl-2-
Another method provided by Miyano et al.9 to pre-
pare
20-diphenylphosphinoyl-1,10-binaphthalenyl-2-ol
Treatment of 20-diphenylphosphinoyl-1,10-binaphthal-
enyl-2-ol 4 with (1S)-(+)-10-camphorsulfonyl chloride in the
presence of triethylamine as a base and dichloromethane
* Corresponding author. Tel.: +86-21-64163300x3435;fax: +86-21-
64163300;e-mail: zhaoguo@mail.sioc.ac.cn
0957-4166/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2003.10.034

18
Y. Luo et al. / Tetrahedron: Asymmetry 15 (2004) 17–19
with the same conditions reported.2 Therefore, chiral
MOPs oxides could easily be derived from the com-
mon starting materials 5a and 5b, and the MOPs oxides
obtained thus conveniently upgraded to >99% ee by
simple recrystallization. The absolute configuration of
the two diasteroisomers can simply be determined by
converting one of them into an identified ligand,
2-diphenylphosphinoyl-20-methoxyl-1,10-binaphthalenes
according to literature.2 For example, 5b was converted
into 2-diphenylphosphinoyl-20-methoxyl-1,10-binaphthal-
ene with 99% yield upon hydrolysis and methyl protec-
tion. The stereochemistry was determined to be (R)- for
the naphthalene moiety after comparing the sign of
specific rotation and spectroscopic data with a reported
sample.2
Scheme 1. Preparation of racemic 20-diphenylphosphinoyl-1,10-
binaphthalenyl-2-ol.
We also made 20-diphenylphosphanyl-1,10-binaphthal-
enyl-2-ol and investigated the direct esterification reac-
tion of it with (1S)-(+)-10-camphorsulfonyl chloride in
the presence of NaH in THF. It was found that no
esterification occurred and that only the oxidized
product 4 could be detected apart from the starting
material. This result is the same as the literature.10
as solvent at room temperature, formed the racemic
ester 5 in high yield (Scheme 2).
However, when the same strategy was applied to resolve
20-di(p-tolyl)phosphinoyl-1,10-binaphthalenyl-2-ol, no
esterification product could be detected and the starting
material was recovered. The reaction also failed to give
product when NaH was used as base and DMF as
solvent.
However, when 20-di(p-tolyl)phosphanyl-1,10-binaph-
thalenyl-2-ol 6, which was prepared by reaction of
chlorodi(p-tolyl)phosphine with dilithium salt 3, and
(1S)-(+)-10-camphorsulfonyl chloride were employed as
the starting materials (Scheme 3), the reaction proceeded
in THF with NaH as the base to give the ester 7 in 50%
yield, accompanied with the oxidized starting material,
20-di(p-tolyl)phosphinoyl-1,10-binaphthalenyl-2-ol and a
little of unreacted 6. It should be mentioned that 7 was
not the direct esterification product;it was the oxidized
product of the direct esterification product. No direct
esterification product was isolated even if less than 1
mole equivalent of (1S)-(+)-10-camphorsulfonyl chlo-
ride was used, and the yield could not be improved
upon, when more (1S)-(+)-10-camphorsulfonyl chloride
was employed.
Scheme 2. Resolution of 20-diphenylphosphinoyl-1,10-binaphthalenyl-
2-ol.
After extensive screening of the common solvents, we
found that the diastereoisomers of 5 could be separated
by chromatography on silica gel with diethyl ether and
diisopropyl ether (5:1) as an eluent. Thus, 5a and 5b
were obtained in decent yields with good diastereomeric
purity (de: P 95%). Both 5a and 5b were easily hydro-
lyzed to (R)- or (S)-20-diphenylphosphinoyl-1,10-bi-
naphthalenyl-2-ol, respectively, in quantitative yield
Scheme 3. Resolution of 20-di(p-tolyl)phosphanyl-1,10-binaphthalenyl-2-ol.

Y. Luo et al. / Tetrahedron: Asymmetry 15 (2004) 17–19
19
1
11. Analytical data for 5a, 5b, 7a, 7b. 5a: H NMR (d, ppm;
CDCl3): 8.18 (dd, 1H, J ¼ 8:4, 2.1 Hz), 7.92 (d, 1H,
J ¼ 8:1 Hz), 7.83 (dd, 1H, J ¼ 11:4, 8.4 Hz), 7.77–7.72 (m,
2H), 7.56–7.11 (m, 16H), 6.96 (d, 1H, J ¼ 8:7 Hz), 2.86 (d,
1H, J ¼ 15:0 Hz), 2.46 (d, 1H, J ¼ 15:0 Hz), 2.28–2.19 (m,
1H), 2.04–1.94 (m, 2H), 1.24 (d, 2H, J ¼ 9:0 Hz), 0.80 (s,
Ester 7 was also separated into 7a and 7b by chroma-
tography on silica gel with Et2O as eluent. Both 7a and
7b serve as key intermediates in monophosphine syn-
thesis.11
In summary, we have provided a novel method for
preparing chiral MOPs. This method involves the simple
resolution of hydroxy monophosphines or their oxides
bearing a naphthalene moiety. The enantiomerically
pure form of 4 and 6 can allow the rapid construction
of a series of chiral monophosphine ligands.
3H), 0.57 (s, 3H); 13C NMR (d, ppm;CDCl ): camphor:
3
213.2, 57.6, 48.9, 47.4, 42.6, 42.1, 26.6, 24.9, 19.4, 19.3,
aryl: 146.0–119.9; 31P NMR (d, ppm;CDCl 3): 29.4;IR
(KBr;wavenumber, cm À1): 3056 (m), 2959 (s), 1746 (vs),
1591 (m), 1509 (m), 1437 (s), 1371 (vs), 1198 (vs), 1168
(vs), 1116 (s), 964 (s), 941 (s), 819 (vs), 749 (s), 699 (vs), 539
(s), 524 (s);MS (ESI): m=z 685.2 [M+1], 686.2 [M+2],
707.1 [M+1]Na, 708.1 [M+2]Na;HRMS m=z calcd for
C42H38O5SP [M+1]þ: 685.2174, found: 685.2172;De: 98%.
5b: 1H NMR (d, ppm;CDCl 3): 8.16 (dd, 1H, J ¼ 8:4,
2.1 Hz), 7.92 (d, 1H, J ¼ 8:1 Hz), 7.84 (dd, 1H, J ¼ 11:4,
8.4 Hz), 7.77–7.72 (m, 2H), 7.56–7.13 (m, 16H), 6.96 (d,
1H, J ¼ 8:4 Hz), 3.1 (d, 1H, J ¼ 15:0 Hz), 2.25–2.16 (m,
1H), 2.08 (d, 1H, J ¼ 15:0 Hz), 1.97–1.88 (m, 2H), 1.82–
1.75 (m, 2H), 1.37–1.20 (m, 2H), 0.68 (s, 3H), 0.41 (s, 3H);
13C NMR (d, ppm;CDCl 3): camphor: 213.4, 57.4, 48.8,
47.4, 42.4, 42.1, 26.6, 24.3, 19.2, 19.0, aryl: 145.7–120.2;
Acknowledgements
We thank the National Natural Science Foundation of
China and the Chinese Academy of Sciences for finan-
cial support.
31P NMR (d, ppm;CDCl ): 29.4;IR (KBr;wavenumber,
References and Notes
3
cmÀ1): 3055 (m), 2959 (s), 1747 (vs), 1591 (m), 1509 (m),
1437 (s), 1362 (vs), 1199 (s), 1168 (vs), 1116 (s), 965 (s), 941
(s), 817 (vs), 749 (s), 699 (vs), 539 (s), 524 (s);MS (ESI):
m=z 685.2 [M+1], 686.2 [M+2], 707.1 [M+1]Na, 708.1
[M+2]Na;HRMS m=z calcd for C42H38O5 SP [M+1]þ:
685.2174, found: 685.2172;De: 95%. 7a: 1H NMR (d,
ppm;CDCl 3): 8.02 (dd, 1H, J ¼ 9:0, 2.1 Hz), 7.94–7.87 (m,
2H), 7.74 (dd, 2H, J ¼ 11:1, 8.7 Hz), 7.52 (dd, 2H, J ¼ 6:9,
8.7 Hz), 7.38–7.25 (m, 7H), 7.17–7.11 (m, 2H), 7.01–6.94
(m, 2H), 6.89 (dd, 2H, J ¼ 7:8, 2.4 Hz), 2.82 (d, 1H,
J ¼ 15:0 Hz), 2.4 (d, 1H, J ¼ 15:0 Hz);2.87 (s, 3H), 2.25
(s, 3.5H), 2.22–2.19 (m, 0.5H), 2.04–1.76 (m, 4H), 1.26–
1.23 (m, 2H), 0.80 (s, 3H), 0.56 (s, 3H); 13C NMR (d, ppm;
CDCl3): 213.2, 57.6, 48.9, 47.4, 42.6, 42.2, 26.6, 25.0,
21.41, 21.40, 21.37, 21.36, 19.5, and 19.3, aryl: 146.0–
120.0; 31P NMR (d, ppm;CDCl 3): 29.8. IR (KBr;
wavenumber, cmÀ1): 2958 (m), 1748 (vs), 1601 (m), 1369
(vs), 1216 (s), 1197 (s), 1168 (vs), 1114 (s), 965 (s), 941 (s),
810 (vs), 749 (s), 681 (s), 659 (s), 526 (vs);MS (ESI): m=z
713.2 [M+1];714.2 [M+2];735.2 [M+1]Na. HRMS calcd
for C44H41O5SPNa [M+1]Naþ: 735.2341, found: 735.2304.
De: 97%. 7b: 1H NMR (d, ppm;CDCl 3): 8.00 (dd, 1H,
J ¼ 8:7, 2.1 Hz), 7.95–7.90 (m, 2H), 7.73 (dd, 2H,
J ¼ 11:1, 8.4 Hz), 7.52–7.45 (m, 2H), 7.38–7.24 (m, 6H),
7.15–7.12 (m, 2H), 7.03 (dd, 2H, J ¼ 8:1, 2.4 Hz), 6.96 (d,
1H, J ¼ 13:8 Hz), 6.90 (dd, 2H, J ¼ 7:8, 2.4 Hz), 3.08 (d,
1H, J ¼ 15:0 Hz), 2.3 (s, 3H), 2.26 (s, 3.5H), 2.19–2.18 (m,
0.5H), 2.06 (d, 1H, J ¼ 15:0 Hz), 2.00–1.76 (m, 4H), 1.34–
1.25 (m, 2H), 0.67 (s, 3H), 0.40 (s, 3H); 13C NMR (d, ppm;
CDCl3): Camphor: 213.3, 57.4, 48.8, 47.4, 42.36, 42.1,
26.6, 24.3, 21.43, 21.41, 21.38, 21.36, 19.2, 19.0, aryl:
1. Kurz, L.;Lee, G.;Morgans, D.;Waldyke, J. M. J.;Ward,
D. Tetrahedron Lett. 1990, 31, 6321–6324.
2. Uozumi, Y.;Tanahashi, A.;Lee, S.-Y.;Hayashi, T.
J. Org. Chem. 1993, 58, 1945–1948.
3. (a) Uozumi, Y.;Hayashi, T. J. Am. Chem. Soc. 1991, 113,
9887–9888;(b) Hayashi, T.;Uozumi, Y. Pure Appl. Chem.
1992, 60, 1911–1916;(c) Uozumi, Y.;Lee, S.-Y.;Hayashi,
T. Tetrahedron Lett. 1992, 33, 7185–7188;(d) Uozumi, Y.;
Hayashi, T. Tetrahedron Lett. 1993, 34, 2335–2338;(e)
Uozumi, Y.;Kitayama, K.;Hayashi, T.
Asymmetry 1993, 4, 2419–2422.
Tetrahedron:
4. Matsumoto, Y.;Naito, M.;Uozumi, Y.;Hayashi, T.
Chem. Soc., Chem. Commun. 1993, 1468–1469.
5. Hayashi, T.;Iwamura, H.;Naito, M.;Matsumoto, Y.;
Uozumi, Y.;Miki, M.;Yanagi, K. J. Am. Chem. Soc.
1994, 116, 775–776.
6. (a) Kodama, H.;Taiji, T.;Ohta, T.;Furukawa, I.
Tetrahedron: Asymmetry 2000, 11, 4009–4015;(b) Uoz-
umi, Y.;Suzuki, N.;Ogiwara, A.;Hayashi, T. Tetrahedron
1994, 50, 4293–4302.
J.
7. (a) Sakai, N.;Mano, S.;Nozaki, K.;Takaya, H.
J. Am.
Chem. Soc. 1993, 115, 7033–7034;(b) Nozaki, K.;Li, W.;
Horiuchi, T.;Takaya, H. J. Org. Chem. 1996, 61, 7658–
7659;(c) Horiachi, T.;Ohata, T.;Shirakawa, E.;Nozaki,
K.;Takaya, H. J. Org. Chem. 1997, 62, 4285–4292;(d)
Nozaki, K.;Sakai, N.;Nanno, T.;Higashijima, T.;Mano,
S.;Horiachi, T.;Takaya, H. J. Am. Chem. Soc. 1997, 119,
4413–4423.
8. (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.
141.5–120.3; 31P NMR (d, ppm;CDCl ): 29.8;IR (KBr;
3
wave number, cmÀ1): 2958 (m), 1748 (vs), 1601 (m), 1362
(vs), 1216 (s), 1197 (s), 1167 (vs), 1114 (s), 965 (s), 941 (s),
811 (vs), 774 (s), 749 (s), 681 (s), 660 (s), 526 (vs);MS (ESI)
m=z 713.2 [M+1], 714.2 [M+2], 715.2 [M+3], 735.2
9. Hattori, I.;Sakamoto, J.;Hayshizaka, N.;Miyano, S.
Synthesis 1994, 199–202.
10. Kadyrov, R.;Heinicke, J.;Kinderman, M. K.;Heller, D.;
Fischer, C.;Selke, R.;Fischer, A. K.;Jones, P. G. Chem.
Ber. 1997, 130, 1663–1670.
[M+1]Na;HRMS
m=z calcd for C44H41O5SPNa
[M+1]Naþ: 735.2328, found: 735.2304;De: 99%.