Mild and chemoselective synthesis of lactones from diols using a novel metal-ligand bifunctional catalyst.

Article abstract of DOI:10.1021/ol026091h

[reaction: see text] A novel amino alcohol-based Ir bifunctional complex acts as an efficient catalyst for oxidative lactonization of 1,4- or 1,5-diols with a substrate-to-catalyst molar ratio of 200-1000 in acetone or butanone. The reaction proceeds with broad functional group tolerance to give lactone in high yield at room temperature. The catalyst precursor Cp*IrCl[OCH(2)C(C(6)H(5))(2)NH(2)] is isolated and characterized by a single-crystal X-ray analysis.

Full text of DOI:10.1021/ol026091h

ORGANIC
LETTERS
2
002
Vol. 4, No. 14
361-2363
Mild and Chemoselective Synthesis of
Lactones from Diols Using a Novel
Metal−Ligand Bifunctional Catalyst
2
Takeyuki Suzuki, Kenji Morita, Mika Tsuchida, and Kunio Hiroi*
Department of Synthetic Organic Chemistry, Tohoku Pharmaceutical UniVersity,
4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi 981-8558, Japan
khiroi@tohoku-pharm.ac.jp
Received April 27, 2002
ABSTRACT
A novel amino alcohol-based Ir bifunctional complex acts as an efficient catalyst for oxidative lactonization of 1,4- or 1,5-diols with a substrate-
to-catalyst molar ratio of 200−1000 in acetone or butanone. The reaction proceeds with broad functional group tolerance to give lactone in
high yield at room temperature. The catalyst precursor Cp*IrCl[OCH C(C H ) NH ] is isolated and characterized by a single-crystal X-ray analysis.
2 6 5 2 2
The oxidative lactonization of diols is useful for the synthesis
of a variety of natural products.1,2 The reaction is considered
to proceed via two steps: the initial chemoselective oxidation
to hydroxy aldehyde, which is in equilibrium with the lactol,
and then oxidation of the lactol to lactone (Scheme 1).
however, is not free of problems, as often a large excess
(10-26 equiv) of expensive silver salts is required and the
3
reagent is inhibited by sulfide groups. To date, several
4
catalytic reactions have been developed, and the reactions
4a,f
required high temperatures (>180 °C) or co-oxidants such
4
b
4c
4d,e,j,k
as tolane, PhBr, R,â-unsaturated ketone,
allyl methyl
4
g
4h,i
carbonate, or N-methylmorpholine N-oxide to be per-
formed under lower temperature. During the past decade,
some catalytic reactions using clean cooxidants such as
Scheme 1
5
(
76.
3) Fetizon, M.; Golfier, M.; Louis, J.-M. Tetrahedron 1975, 31, 171-
1
(
4) (a) 2CuO‚Cr2O3: Kyrides, J. P.; Zienty, F. B. J. Am. Chem. Soc.
1
946, 68, 1385-1385. (b) Ru3(CO)12-tolane: Shvo, Y.; Blum, Y.; Reshef,
D.; Menzin, M. J. Organomet. Chem. 1982, 226, C21-C25. (c) Pd(OAc)2-
PhBr: Tamaru, Y.; Yamada, Y.; Inoue, K.; Yamamoto, Y.; Yoshida, Z. J.
Org. Chem. 1983, 48, 1286-1292. (d) RhH(PPh3)4-R,â-unsaturated
ketone: Ishii, Y.; Suzuki, K.; Ikariya, T.; Saburi, M.; Yoshikawa, S. J.
Org. Chem. 1986, 51, 1, 2822-2824. (e) RuH2(PPh3)4-R,â-unsaturated
ketone: Ishii, Y.; Osakada, K.; Ikariya, T.; Saburi, M.; Yoshikawa, S. J.
Org. Chem. 1986, 51, 2034-2039. (f) RuH2(PPh3)4-acetone: Murahashi,
S.-I.; Naota, T.; Ito, K.; Maeda, Y.; Taki, H. J. Org. Chem. 1987, 52, 4319-
4327. (g) RuH2(PPh3)4-allyl methyl carbonate: Minami, I.; Tsuji, J.
A common approach for this reaction is to use a stoichio-
metric amount of silver carbonate on Celite.1,3 This reagent,
(
1) (a) Procter, G. In ComprehensiVe Organic Synthesis; Trost, B. M.,
Fleming. I., Ley, S. V., Eds.; Pergamon: Oxford, 1991; Vol. 7, pp 312-
18. (b) Kano, S.; Shibuya, S.; Ebata, T. Heterocycles 1980, 14, 661-711.
2) For recent examples of the natural product synthesis, see: (a) Suzuki,
3
+
(
Tetrahedron 1987, 43, 3903-3915. (h) n-Pr4N RuO4-NMO: Block, R.;
T.; Ohmori, K.; Suzuki, K. Org. Lett. 2001, 3, 1741-1744. (b) Zhu, X.;
Yu, B.; Hui, Y.; Higuchi, R.; Kusano, T.; Miyamoto, T. Tetrahedron Lett.
Brillet, C. Synlett 1991, 829-830. (i) Ley, S. V.; Norman, J.; Griffith, W.
P.; Marsden, S. P. Synthesis 1994, 639-666. For enantioselective reac-
tions: (j) Ishii, Y.; Osakada, K.; Ikariya, T.; Saburi, M.; Yoshikawa, S.
Chem. Lett. 1982, 1179-1182. (k) Nozaki, K.; Yoshida, M.; Takaya, H. J.
Organomet. Chem. 1994, 473, 253-256.
2000, 41, 717-719. (c) Amaike, M.; Mori, K. Liebigs Ann. 1995, 1451-
1454. (d) Ley, S. V.; Norman, J.; Pinel, C. Tetrahedron Lett. 1994, 35,
2095-2098.
1
0.1021/ol026091h CCC: $22.00 © 2002 American Chemical Society
Published on Web 06/12/2002

acetone,5a,7b,c hydrogen peroxide,5b or molecular oxygen5c
were reported; however, there is much room for improvement
of the catalytic activity and selectivity. We now disclose a
new efficient method using a novel metal-ligand bifunc-
tional catalyst and acetone or 2-butanone as a cooxidant.
This method is high-yielding, clean, operationally simple,
and chemoselective. Therefore, it meets the standards for
the contemporary of organic synthesis.
Table 1. Oxidative Lactonization of Diols Catalyzed by an Ir
Catalyst 4a
6
,7
Treatment of a mixture of pentamethylcyclopentadienyl-
8
9
iridium chloride dimer [Cp*IrCl
2 2
] and 2,2-diphenylglycinol
in CH Cl with aqueous KOH solution at room temperature
2
2
for 30 min under argon afforded the dark red Ir catalyst in
quantitative yield. Thus, when a 1 M solution of 1,2-bis-
(hydroxymethyl)benzene (1a) in dry acetone (13.6 mol equiv)
containing the Ir catalyst (S/C ) 200) was stirred at room
temperature for 4 h, phthalide (2a) was obtained in quantita-
10
tive yield. The reaction of 1a using reagent grade of acetone
proceeds equally well, giving the lactone quantitatively
(Scheme 2).
Scheme 2
A variety of 1,4- or 1,5-diols can be transformed to the
corresponding lactones in high yield (Table 1). The reactions
of 1b-d gave corresponding lactones without epimerization.
In the case of unsymmetrical diol 1g and 1h, the less hindered
(
5) (a) Metal polyhydrides-acetone: Lin, Y.; Zhu, X.; Zhou, Y. J.
Organomet. Chem. 1992, 429, 269-274. (b) Heteropolyacid-H2O2: Ishii,
Y.; Yoshida, T.; Yamawaki, K.; Ogawa, M. J. Org. Chem. 1988, 53, 5549-
5
552. (c) Pd(OAc)2-O2: Nishimura, T.; Onoue, T.; Ohe, K.; Uemura, S.
J. Org. Chem. 1999, 64, 6750-6755.
a
(
6) For asymmetric transfer hydrogenation using a metal-ligand bifunc-
Unless otherwise stated, the reaction was carried out at room
6
tional catalyst, see: RuCl(Tsdpen)(µ -arene): (a) Hashiguchi, S.; Fujii, A.;
temperature using a 1.0 M solution of diol (1.0 mmol) in acetone. Diol/Ir
) 200:1. Isolated yield. c Reaction using 50 g of 1e in 140 mL of
b
Takehara, J.; Ikariya, T.; Noyori, R. J. Am. Chem. Soc. 1995, 117, 7562-
d
7
563. (b) Takehara, J.; Hashiguchi, S.; Fujii, A.; Inoue, S.; Ikariya, T.;
2-butanone (4.0 M) under reflux with S/C ) 1000. Reaction using a 2.0
M acetone solution. e The reaction was carried out using a 0.25 M solution
Noyori, R. Chem. Commun. 1996, 233-234. (c) Fujii, A.; Hashiguchi, S.;
f
1
Uematsu, N.; Ikariya, T.; Noyori, R. J. Am. Chem. Soc. 1996, 118, 2521-
of 1g in CH3CN containing 4 molar equiv of acetone. Determined by H
2
522. (d) Uematsu, N.; Fujii, A.; Hashiguchi, S.; Ikariya, T.; Noyori, R. J.
Am. Chem. Soc. 1996, 118, 4916-4917. (e) Haack, K.-J.; Hashiguchi, S.;
NMR.
Fujii, A.; Ikariya, T.; Noyori, R. Angew. Chem., Int. Ed. Engl. 1997, 36,
2
85-288. (f) Hashiguchi, S.; Fujii, A.; Haack, K.-J.; Matsumura, K.; Ikariya,
T.; Noyori, R. Angew. Chem., Int. Ed. Engl. 1997, 36, 288-290. (g)
Matsumura, K.; Hashiguchi, S.; Ikariya, T.; Noyori, R. J. Am. Chem. Soc.
hydroxyl groups were oxidized selectively to give 2g and
2
h. The reaction of 1,4-pentanediol (1f) gave γ-valerolactone
1
1
3
997, 119, 8738-8739. (h) Noyori, R.; Hashiguchi, S. Acc. Chem. Res.
997, 30, 97-102. (i) Yamada, I.; Noyori, R. Org. Lett. 2000, 2, 3425-
427. (j) Yamakawa, M.; Yamada, I.; Noyori, R. Angew. Chem., Int. Ed.
(2f) in 88% yield. 2-(3-Hydroxypropyl)phenol (1j) also
afforded 2j in 95% yield.
Since transfer hydrogenation of ketones is reversible, a
substrate concentration as low as 0.1 M is required for ob-
taining high yield in the transfer hydrogenation of aceto-
phenone in 2-propanol (2-propanol/ketone substrate )
Engl. 2001, 40, 2818-2821. (k) Noyori, R.; Yamakawa, M.; Hashiguchi,
S. J. Org. Chem. 2001, 66, 7931-7944. Cp*MCl(Tsdiamine) (M ) Rh,
Ir): (l) Mashima, K.; Abe, T.; Tani, K. Chem. Lett. 1998, 1199-1200. (m)
Mashima, K.; Abe, T.; Tani, K. Chem. Lett. 1998, 1201-1202. (n) Murata,
K.; Ikariya, T.; Noyori, R. J. Org. Chem. 1999, 64, 2186-2187. (o) Mao,
J.; Baker, D. C. Org. Lett. 1999, 1, 841-843.
2362
Org. Lett., Vol. 4, No. 14, 2002

1
36:1).6a On the other hand, the reaction using a 0.27 M
solution of 1a in toluene proceeds quantitatively in the
presence of a slight excess of acetone and the Ir catalyst 4
(acetone/diol substrate/4 ) 2.5:1:0.005), while 2 molar equiv
of oxidant is required by the stoichiometry for the oxidative
lactonization of diols. Therefore, a 50 g scale reaction can
be performed easily with high concentration with S/C ) 1000
to give 2e in 89% yield after distillation (Table 1, entry 6).
To test the tolerance of functional groups, 1a was oxidized
in acetone containing an equimolar amount of coordinative
compound. The reaction proceeded without problems in
>
92% yield in the presence of 1-tetradecene, methyl
decanoate, di-n-hexyl ether, benzyl cyanide, thioanisole, or
N-methylpyrrolidinone. Moreover the acid-sensitive additive
such as styrene oxide or the trimethylsilyl ether of 4-bromo-
benzyl alcohol also remains intact during the reaction.
However, the addition of pyrrolidinone or 1-dodecyne
completely retarded the reaction.
Having succeeded in catalytic lactonization, we then turned
our attention to the elucidation of the catalyst structure. A
catalyst precursor Ir(III) complex 3 that was prepared from
a 1:2 mixture of [Cp*IrCl
]
2 2
and 2,2-diphenylglycinol in
Figure 1. ORTEP plot (50% probability ellipsoids) of the
molecular structure of Cp*IrCl[OCH C(C NH ] (3).
2
6 5
H )
2
2
CH Cl with triethyamine was isolated as a yellow crystal
2
2
after recrystallization from chloroform. The single-crystal
X-ray analysis illustrated in Figure 1 indicates that the 18
electron Ir(III) complex has a distorted octahedral coordina-
tion environment with Cp*, amino, alkoxide, and chloro
ligands. Noteworthy is the very short Cl‚‚‚HN distance of
In summary, we have accomplished the practical synthesis
of lactones from diols catalyzed by a novel Ir catalyst. Further
investigation for enantioselective reaction is ongoing.11
2
.71 Å, which is ascribed from intramolecular hydrogen
bonding. Although this preformed mononuclear Ir complex
does not possess catalytic activities by itself, treating the
complex 3 with aqueous KOH in CH Cl gave the active
Acknowledgment. This work was financially supported
by the Uehara Memorial Foundation. We thank Professor
Ryoji Noyori of Nagoya University and Professor Takao
Ikariya of Tokyo Institute of Technology for helpful dis-
cussions and Dr. Motoo Shiro of Rigaku Cooperation for
the single-crystal X-ray analysis of 3.
3
2
2
catalyst 4, which catalyzed the lactonization of 1a in acetone
to give 2a quantitatively at room temperature for 4 h.
(
7) Kinetic resolution of secondary alcohols using a metal-ligand
bifunctional catalyst: (a) Hashiguchi, S.; Fujii, A.; Haack, K.-J.; Ikariya,
Supporting Information Available: The experimental
procedure for the oxidative lactonization and the single-
crystal X-ray information for 3. This material is available
free of charge via the Internet at http://pubs.acs.org.
T.; Matsumura, K.; Noyori, R. Angew. Chem., Int. Ed. Engl. 1997, 36, 288-
2
90. Lactonization using Cp*Ru complex: (b) Ito, M.; Osaku, A.; Ikariya,
T. Abstracts of Papers. 79th National Meeting of the Chemical Society of
Japan, Kobe, Mar 28-31, 2001; Chemical Society of Japan: Tokyo, 2001;
Abstract 1H326. (c) Ito, M.; Osaku, A.; Ikariya, T. Abstracts of Papers.
4
8th Symposium on Organometallic Chemistry, Yokohama, Sep 18-19,
2
001; Kinki Chemical Society: Osaka, 2001; Abstract PB142.
OL026091H
(
8) Kang, J. W.; Moseley, K.; Maitlis, P. M. J. Am. Chem. Soc. 1969,
1, 1, 5970-5977.
9) Newman, M. S.; Edwards, W. M. J. Am. Chem. Soc. 1954, 76, 1840-
845.
10) The use of other ligands such as 2-aminoethanol and N-tosylethyl-
9
(
(11) For recent examples of oxidative desymmetrization, see: (a) Jensen,
D. R.; Pugsley, J. S.; Sigman, M. S. J. Am. Chem. Soc. 2001, 123, 7475-
7476. (b) Ferreira E. M.; Stoltz B. M. J. Am. Chem. Soc. 2001, 123, 7725-
7726.
1
(
endiamine instead of 2,2-diphenylglycinol showed lower reactivity.
Org. Lett., Vol. 4, No. 14, 2002
2363