Tightly convoluted polymeric phosphotungstate catalyst: An oxidative cyclization of alkenols and alkenoic acids

Article abstract of DOI:10.1021/ol070258v

Equation Presented A tightly convoluted polymeric phosphotungstate catalyst was prepared via ionic assembly of H₃PW₁₂O₄₀ and poly(alkylpyridinium). An oxidative cyclization of various alkenols and alkenoic acids was efficiently promoted by the polymeric catalyst in aq H ₂O₂ in the absence of organic solvents to afford the corresponding cyclic ethers and lactones in high yield. The catalyst was reused four times without loss of catalytic activity.

Full text of DOI:10.1021/ol070258v

ORGANIC
LETTERS
2007
Vol. 9, No. 8
1501-1504
Tightly Convoluted Polymeric
Phosphotungstate Catalyst: An
Oxidative Cyclization of Alkenols and
Alkenoic Acids
Yoichi M. A. Yamada, Haiqing Guo, and Yasuhiro Uozumi*
Institute for Molecular Science (IMS), Myodaiji, Okazaki, Aichi 444-8787, Japan
uo@ims.ac.jp
Received February 1, 2007
ABSTRACT
A tightly convoluted polymeric phosphotungstate catalyst was prepared via ionic assembly of H3PW12O40 and poly(alkylpyridinium). An oxidative
cyclization of various alkenols and alkenoic acids was efficiently promoted by the polymeric catalyst in aq H2O2 in the absence of organic
solvents to afford the corresponding cyclic ethers and lactones in high yield. The catalyst was reused four times without loss of catalytic
activity.
The development of immobilized catalysts exhibiting high
aquacatalytic activity1 and recyclability2 has become an
important topic in organic chemistry today.3,4 We have
developed amphiphilic polymer resin-supported transition-
metal complexes and nanoparticles that catalyze various
organic transformations in water under heterogeneous
conditions.5-7 Recently, we have also presented a novel self-
assembling protocol for the preparation of solid-phase
catalysts where metal species served as cross-linkers of non-
cross-linked polymeric ligands as well as catalytically active
centers.8,9 Thus, for example, an ionically cross-linked
polymeric phosphotungstate catalyst PWAA was prepared
via salt formation of PW12O403- with poly{{[3-(acryolylami-
no)propyl]dodecyldimethylammonium nitrate}-co-(N-iso-
(1) For reviews, see: (a) Li, C.-J.; Chan, T.-H. Organic Reactions in
Aqueous Media; Wiley-VCH: New York, 1997. (b) Grieco, P. A. Organic
Synthesis in Water; Kluwer Academic Publishers: Dordrecht, 1997. (c)
Herrmann, W. A.; Kohlpaintner, C. W. Angew. Chem., Int. Ed. Engl. 1993,
32, 1524.
(2) For reviews, see: (a) Bailey, D. C.; Langer, S. H. Chem. ReV. 1981,
81, 109. (b) Shuttleworth, S. J.; Allin, S. M.; Sharma, P. K. Synthesis 1997,
1217. (c) Shuttleworth, S. J.; Allin, S. M.; Wilson, R. D.; Nasturica, D.
Synthesis 2000, 1035. (d) Do¨rwald, F. Z. Organic Synthesis on Solid Phase;
Wiley-VCH: Weinheim, 2000. (e) Ley, S. V.; Baxendale, I. R.; Bream, R.
N.; Jackson, P. S.; Leach, A. G.; Longbottom, D. A.; Nesi, M.; Scott, J. S.;
Storer, R. I.; Taylor, S. J. J. Chem. Soc., Perkin Trans. 1 2000, 3815. (f)
Leadbeater, N. E.; Marco, M. Chem. ReV. 2002, 102, 3217. (g) McNamara,
C. A.; Dixon, M. J.; Bradley, M. Chem. ReV. 2002, 102, 3275. (h) Frenzel,
T.; Solodenko, W.; Kirschning, A. In Polymeric Materials in Organic
Synthesis and Catalysis; Buchmeiser, M. R., Ed.; Wiley-VCH: Weinheim,
2003; p 201. (i) Leadbeater, N. E. Chem. Commun. 2005, 2881. (j) Bai, L.;
Wang, J.-X. Curr. Org. Chem. 2005, 9, 535. (k) Nicolaou, K. C.; Bulger,
P. G.; Sarlah, D. Angew. Chem., Int. Ed. 2005, 44, 4442.
(3) For general reviews on green chemistry, see: (a) Anastas, P. T.;
Warner, J. C. Green Chemistry: Theory and Practice; Oxford Univ.
Press: Oxford, 1998. (b) Green Chemical Syntheses and Processes: Recent
AdVances in Chemical Processing; Anastas, P. T., Heine, L. G., Williamson,
T. C., Ed.; Am. Chem. Soc.: Ohio, 2001. (c) Tundo, P.; Anastas, P.; Black,
D. S.; Breen, J.; Collins, T.; Memoli, S.; Miyamoto, J.; Polyakoff, M.;
Tumas, W. Pure Appl. Chem. 2000, 72, 1207.
(4) For reviews on polymeric aquacatalysts, see: (a) Uozumi, Y. J. Synth.
Org. Chem. Jpn. 2002, 60, 1063. (b) Uozumi, Y. Top. Curr. Chem. 2004,
242, 77.
10.1021/ol070258v CCC: $37.00
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propylacrylamide)12}, a main chain of poly(N-isopropylacryl-
amide) bearing branched ammonium cation parts (Figure 1,
top).10 The polymeric phosphotungstate PWAA catalyzed the
oxidation of alkenes, amines, and sulfides; however, it could
not be sufficiently recycled presumably due to its physical
fragility. More rigid assembling of the cationic polymer with
the phosphotungstate anion might provide more stable
polymeric catalysts. Here we would like to report the
amphiphilic pyridinium polymer 1 bearing main-chain cat-
ionic groups constructed with a tightly convoluted pyridinium
phosphotungstate salt which exhibited high catalytic activity
and recyclability for oxidative cyclization of alkenols and
alkenoic acids (Figure 1, bottom). The polymeric pyridinium
phosphotungstate was found to catalyze the oxidative cy-
clization of a wide variety of (E)- and (Z)-alkenols as well
as (E)- and (Z)-alkenoic acids with high stereospecificity in
aqueous hydrogen peroxide under organic solvent-free condi-
tions and was reused four times without loss of catalytic
activity.
A polymeric tungsten catalyst was readily prepared from
poly[1,8-dibromooctane-co-1,3-di(4-pyridyl)propane] (1)11
with H3PW12O40 (2)12 according to the preparation of
(5) For aquacatalytic reactions with amphiphilic resin-supported transi-
tion-metal complexes, see: (a) Uozumi, Y.; Danjo, H.; Hayashi, T.
Tetrahedron Lett. 1997, 38, 3557. (b) Danjo, H.; Tanaka, D.; Hayashi, T.;
Uozumi, Y. Tetrahedron 1999, 55, 14341. (c) Uozumi, Y.; Danjo, H.;
Hayashi, T. J. Org. Chem. 1999, 64, 3384. (d) Uozumi, Y.; Watanabe, T.
J. Org. Chem. 1999, 64, 6921. (e) Shibatomi, K.; Nakahashi, T.; Uozumi,
Y. Synlett 2000, 1643. (f) Uozumi, Y.; Nakai, Y. Org. Lett. 2002, 4, 2997.
(g) Uozumi, Y.; Nakazono, M. AdV. Synth. Catal. 2002, 344, 274. (h)
Uozumi, Y.; Kimura, T. Synlett 2002, 2045. (i) Uozumi, Y.; Kobayashi,
Y. Heterocycles 2003, 59, 71. (j) Nakai, Y.; Uozumi, Y. Org. Lett. 2005,
7, 291. (k) Uozumi, Y.; Kikuchi, M. Synlett 2005, 1775. (l) Nakai, Y.;
Kimura, T.; Uozumi, Y. Synlett 2006, 3065. (m) Uozumi, Y.; Suzuka, T.;
Kawade, R.; Taknaka, H. Synlett 2006, 2109.
(6) For aquacatalytic reactions with amphiphilic resin-supported nano-
metal particles, see: (a) Uozumi, Y.; Nakao, R. Angew. Chem., Int. Ed.
2003, 42, 194. (b) Nakao, R.; Rhee, H.; Uozumi, Y. Org. Lett. 2005, 7,
163. (c) Yamada, Y. M. A.; Uozumi, Y. Org. Lett. 2006, 8, 1375. Yamada,
Y. M. A.; Arakawa, T.; Hocke, H.; Uozumi, Y. Angew. Chem., Int. Ed.
2007, 46, 704.
(7) For asymmetric aquacatalytic reactions with chiral amphiphilic resin-
supported transition-metal complexes, see: (a) Uozumi, Y.; Danjo, H.;
Hayashi, T. Tetrahedron Lett. 1998, 39, 8303. (b) Uozumi, Y.; Shibatomi,
K. J. Am. Chem. Soc. 2001, 123, 2919. (c) Hocke, H.; Uozumi, Y. Synlett
2002, 2049. (d) Uozumi, Y.; Tanaka, H.; Shibatomi, K. Org. Lett. 2004, 6,
281. (e) Hocke, H.; Uozumi, Y. Tetrahedron 2003, 59, 619. (f) Heiko, H.;
Uozumi, Y. Tetrahedron 2004, 60, 9297. (g) Uozumi, Y.; Kimura, M.
Tetrahedron: Asymmetry 2006, 17, 161. (h) Kobayashi, Y.; Tanaka, D.;
Danjo, H.; Uozumi, Y. AdV. Synth. Catal. 2006, 348, 1561. (i) Uozumi,
Y.; Suzuka, T. J. Org. Chem. 2006, 71, 8644.
Figure 1. Assembly of H3PW12O40 and an amphiphilic copolymer
with a branched ligand (top) and a tight assembly of H3PW12O40
and a main-chain pyridinium polymer (bottom).
[π-C5H5N(CH2)15CH3]3PW12O40.13 Thus, when an aqueous
solution of 2 was added to an aqueous solution of 1 at 25
°C, the ionic components assembled to give the polymeric
salt 3 as a white powder (83% yield), which was insoluble
in water, ethanol, ethyl acetate, tetrahydrofuran, dichlo-
romethane, toluene, and hexane (Scheme 1).14
The polymeric phosphotungstate 3 was unambiguously
characterized by spectro- and microscopic studies (MAS 31P-
{1H} NMR, IR spectroscopy, elemental analysis, TEM, SEM,
and EDS). Typical data are shown in Figure 2. MAS 31P-
{1H} NMR of the polymeric 3 showed a narrow singlet
resonance at -16.5 ppm that was identical to a phosphorus
resonance of PW12O40 .
3- 15,16 High-resolution TEM analysis
(8) For a review, see: Yamada, Y. M. A. Chem. Pharm. Bull. 2005, 53,
723.
of 3 revealed that the phosphotungstate clusters were
uniformly dispersed throughout the polymer matrix having
a diameter of ca. 1 nm, which is consistent with the size of
(9) (a) Yamada, Y. M. A.; Ichinohe, M.; Takahashi, H.; Ikegami, S.
Tetrahedron Lett. 2002, 43, 3431. (b) Yamada, Y. M. A.; Takeda, K.;
Takahashi, H.; Ikegami, S. Org. Lett. 2002, 4, 3371. (c) Yamada, Y. M.
A.; Takeda, K.; Takahashi, H.; Ikegami, S. Tetrahedron Lett. 2003, 44,
2379. (d) Yamada, Y. M. A.; Takeda, K.; Takahashi, H.; Ikegami, S. J.
Org. Chem. 2003, 68, 7733. (e) Yamada, Y. M. A.; Takeda, K.; Takahashi,
H.; Ikegami, S. Tetrahedron 2004, 60, 4087. (f) Yamada, Y. M. A.; Maeda,
Y.; Uozumi, Y. Org. Lett. 2006, 8, 4259.
(10) (a) Yamada, Y. M. A.; Ichinohe, M.; Takahashi, H.; Ikegami, S.
Org. Lett. 2001, 3, 1837. (b) Yamada, Y. M. A.; Tabata, H.; Takahashi,
H.; Ikegami, S. Synlett 2002, 2031. (c) Yamada, Y. M. A.; Tabata, H.;
Ichinohe, M.; Takahashi, H.; Ikegami, S. Tetrahedron 2004, 60, 4097. (d)
Hamamoto, H.; Suzuki, H.; Yamada, Y. M. A.; Tabata, H.; Takahashi, H.;
Ikegami, S. Angew. Chem., Int. Ed. 2005, 44, 4536.
(13) Ishii, Y.; Yamawaki, K.; Ura, T.; Yamada, H.; Yoshida, T.; Ogawa,
M. J. Org. Chem. 1988, 53, 3587.
(14) Preparation of 3: To an aqueous solution (30 mL) of poly[1,8-
dibromooctane-co-1,3-di(4-pyridyl)propane] (1) (148 mg, 0.63 mmol of a
pyridinium unit) was added an aqueous solution (70 mL) of H3PW12O40
2
(608 mg, 0.21 mmol) at 25 °C, and the resulting colorless suspension was
stirred for 3 days at the same temperature. The precipitates were collected
by filtration, washed with water, and dried at 5 Pa for 12 h to give 3 (624
mg, 83%) as a colorless powder.
(11) Jegal, J.; Kim, J.-H.; Park, Y.-I.; Lee, K.-H. J. Appl. Polym. Sci.
1994, 54, 65.
(12) (a) Misono, M. Chem. Commun. 2001, 1141. (b) Mizuno, N.;
Misono, M. Chem. Lett. 1987, 967. (c) Okuhara, T. Chem. ReV. 2002, 102,
3641.
(15) Okuhara, T.; Watanabe, H.; Nishimura, T.; Inumaru, K.; Misono,
M. Chem. Mater. 2000, 12, 2230.
(16) (a) Ishii, Y.; Tanaka, H.; Nishiyama, Y. Chem. Lett. 1994, 1. (b)
Massart, R.; Contant, R.; Fruchart, J.-M.; Ciabrini, J.-P.; Fournier, M. Inorg.
Chem. 1977, 16, 2916.
1502
Org. Lett., Vol. 9, No. 8, 2007

Scheme 1. Preparation of a New-Generation Self-Assembled
Table 1. Oxidative Cyclization of Alkenols and Alkenoic
Acids Catalyzed by 3a
Polymeric Tungsten Catalysta
a 1 (3 mol equiv of a pyridinium), 2 (1 mol equiv), water, 25
°C, 3 days.
monomeric PW12O40 .
3- 17 The NMR and TEM observations
3-
indicate the integrity of the monomeric structure of PW12O40
,
whereas a similar phosphotungstate Cs2.5H0.5PW12O40 is
known to form an aggregated tertiary structure ((Cs2.5H0.5-
PW12O40)n; φ ) 100-500 nm).12 An SEM image of 3
confirmed its dendroidal surface. The polymeric phospho-
tungstate 3 was expected to exhibit good catalytic perfor-
mance owing to the immense surface area of the convoluted
composite 3 and the monomeric structure of the phospho-
tungstate cluster.
a All reactions were performed in the presence of 4 (1 mol equiv), 30%
aq H2O2 (2.5 mol equiv), and 3 (0.2 mol % of phosphotungstate) at 50 °C
for 24 h. b The catalyst was reused after being stored for 6 months. c3 (0.4
d
mol %); aq H2O2 (3.5 mol equiv); reaction time, 35 h. Diastereomeric
ratio.
of alkenols with aqueous hydrogen peroxide (Table 1)
producing furanyl and pyranyl carbinols, which are the key
components of biologically active compounds.18,19 Although
only homogeneous transition-metal catalysts have been
developed for oxidative cyclizations so far,20 the development
of immobilized solid-phase catalysts still remains a major
(18) Alali, F. Q.; Liu, X.-X.; Mclaughlin, J. L. J. Nat. Prod. 1999, 62,
504.
(19) (a) Nakata, T.; Schmid, G.; Vranesic, B.; Okigawa, M.; Smith-
Palmer, T.; Kishi, Y. J. Am. Chem. Soc. 1978, 100, 2933. (b) Fukuyama,
T.; Wang, C.-L. J.; Kishi, Y. J. Am. Chem. Soc. 1979, 101, 260. (c) Wuts,
P. G. M.; D’Costa, R.; Butler, W. J. Org. Chem. 1984, 49, 2582. (d) Still,
W. C.; Romero, A. G. J. Am. Chem. Soc. 1986, 108, 2105. (e) Evans, D.
A.; Polniaszek, R. P.; Devries, K. M.; Guinn, D. E.; Mathre, D. J. J. Am.
Chem. Soc. 1991, 113, 7613. (f) Sinha, S.; Sinha-Bagchi, A.; Keinan, E. J.
Am. Chem. Soc. 1995, 117, 1447. (g) Towne, T. B.; McDonald, F. E. J.
Am. Chem. Soc. 1997, 119, 6022. (h) Wang, Z.-M.; Tian, S.-K.; Shi, M.
Tetrahedron Lett. 1999, 40, 977.
(20) For reviews, see: (a) Hartung, J.; Greb, M. J. Organomet. Chem.
2002, 661, 67. (b) Koert, U. Synthesis 1995, 115. (c) Boivin, T. L. B.
Tetrahedron 1987, 43, 3309. Ishii and co-authors reported one entry of the
oxidative cyclization catalyzed by ([C5H5N+(CH2)15CH3]3{PO4[W(O)--
(O2)2]4}3-), where the 5-exo/6-endo cyclization selectivity was 2:1. See:
(d) Sakaguchi, S.; Nishiyama, Y.; Ishii, Y. J. Org. Chem. 1996, 61, 5307.
Figure 2. MAS 31P{1H} NMR (top, left), SEM (top, right; bar
length ) 10 µm), and TEM (bottom; left, bar length ) 20 nm;
right, bar length ) 5 nm) images of the solid-phase catalyst 3.
The aquacatalytic potential of the novel polymeric phos-
photungstate 3 was examined for the oxidative cyclization
(17) (a) Keggin, J. F. Proc. R Soc. London, Ser. A 1934, 144, 75. (b)
Brown, G. M.; Noe-Spirlet, M.-R.; Busing, W. R.; Levy, H. A. Acta. Cryst.
B 1977, 33, 1038.
Org. Lett., Vol. 9, No. 8, 2007
1503

challenge in terms of catalytic activity and recyclability.21
When the oxidations of the cis-alkenols, (Z)-4-hexen-1-ol
(4a), (Z)-4-hepten-1-ol (4b), and (Z)-4-decen-1-ol (4c), were
carried out with 3 (0.2 mol % of PW12O403-) in 30% aqueous
H2O2 at 50 °C, we were pleased to find that the threo-1-(2-
tetrahydrofuranyl)alkanols 5a-c were obtained in 92-98%
yield with complete diastereoselectivity (entries 1-3). The
cyclization of (Z)-5-octen-1-ol (4d) proceeded smoothly to
give the threo-tetrahydropyranyl alcohol 5d in 74% yield
(entry 9). (E)-4-Decen-1-ol (4e) also underwent the cycliza-
tion to give the erythro-product 5e in 82% yield (entry 10).
These stereochemical observations indicate that the cycliza-
tion involves a stereospecific reaction pathway. The second-
ary alcohols 4f and 4g were converted to the corresponding
threo-tetrahydrofuranols 5f and 5g in 86% and 82% yield,
respectively, without control of the stereochemistry at the
C5-position of the tetrahydrofuran (entries 11 and 12).22
Recycling experiments of the insoluble catalyst 3 were
examined in the oxidative cyclization of 4c (entries 3-7).
Thus, the first use of the catalyst afforded 5c in 92% yield.
After being recovered by filtration, washed with water, and
dried in vacuo, the catalyst was reused to give 5c in
quantitative yield. To our delight, the third, fourth, and fifth
uses of the recovered catalyst also provided 5c in 99%, 94%,
and 99% yields, respectively. After the fifth use (entry 7),
the recovered catalyst was stored for 6 months under
atmospheric conditions at ambient temperature and then
subjected to the sixth run (entry 8) to give 94% yield of 5c.
Alkenoic acids were also suitable substrates for the
oxidative cyclization (Scheme 2). Thus, the oxidative cy-
clization of (Z)-4-heptenoic acid (6a), (Z)-6b, and (E)-4-
decenoic acid 6c under similar conditions proceeded ste-
reospecifically to afford the corresponding lactones 7a-c
in 75-85% yield. By using this catalytic system, L-factor
Scheme 2
(leucomycin-inducing factor) 7b, isolated from Streptomyces
griseus,23 was obtained in 85% yield.
In conclusion, the novel tightly convoluted polymeric
phosphotungstate cluster catalyst 3 was readily prepared via
the ionic self-assembly process of a main-chain polypyri-
dinium and phosphotungstic acid. It is noteworthy that this
polymeric catalyst effectively catalyzed the oxidative cy-
clization of a variety of alkenols and alkenoic acids in
aqueous H2O2 under organic solvent-free conditions. The
insoluble catalyst was reused without any loss of catalytic
activity. Extension of this catalytic system to other organic
transformations as well as its application to the synthesis of
natural products are currently in progress.
Acknowledgment. This work was supported by the
CREST program, sponsored by the JST. We also thank the
JSPS (Grant-in-Aid for Scientific Research, no. 15205015
and no. 16790025) and the MEXT (Scientific Research on
Priority Areas, no. 460) for partial financial support of this
work. We are thankful to Dr. Satoru Nakao (IMS) for his
help in measuring SEM, which is supported by the Nano-
technology Support Project (MEXT) and managed by the
IMS.
(21) For recent examples of development, see: (a) Bhaumik, A.; Tatsumi,
T. J. Catal. 2000, 189, 31. (b) Ichihara, J.; Kambara, A.; Iteya, K.; Sugimoto,
E.; Shinkawa, T.; Takaoka, A.; Yamaguchi, S.; Sasaki, Y. Green Chem.
2003, 5, 491.
(22) According to Mizuno and Misono’s studies (ref 12), we speculate
the reaction pathway of the present oxidative cyclization should proceed
via the epoxidation of the alkene (4 or 6) with peroxotungstate generated
in situ and subsequent oxirane ring opening with the intramolecular oxygen
nucleophile to afford the product (5 or 7).
Supporting Information Available: Experimental de-
tails, as well as NMR, SEM, and GC-MS data. This material
is available free of charge via the Internet at http://pubs.acs.org.
(23) Grafe, U.; Eritt, I. J. Antibiot. 1983, 36, 1592.
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