C O M M U N I C A T I O N S
Table 1. Scope of Ketones 1 for In(0)-Catalyzed Allylation with 2
Acknowledgment. This work was partially supported by a Grant-
in-Aid for Scientific Research from the Japan Society for the Promotion
of Science (JSPS). Dr. Va´clav Jurc˘´ık and Mr. Hiroyuki Miyamura (The
University of Tokyo) are acknowledged for their technical assistance.
in Water19
yield
(%) entry
yield
(%)
entry
ketone 1
ketone 1
1
1a: R1 ) Ph,
92 12 1l: R1,2 ) -(CH2)5-
88
Supporting Information Available: Full experimental details and
NMR spectral reproductions for new compounds. This material is
R2 ) Me
2
3
4
5
6
7
8
9
1b: R1 ) 2-F-C6H4,
R2 ) Me
91 13 1m: R1,2 ) -(CH2)4-
90
References
1c: R1 ) 2-Br-C6H4,
R2 ) Me
98 14 1n: R1,2 ) -CHdCH-(CH2)3- 82
(1) Transition Metal Reagents and Catalysts: InnoVations in Organic Synthesis;
Tsuji, J., Ed.; Wiley: Chichester, U.K., 2000.
(2) Reviews on the stoichiometric use of In(0): (a) Ranu, B. C. Eur. J. Org.
Chem. 2000, 2347–2356. (b) Nair, V.; Ros, S.; Jayan, C. N.; Pillai, B. S.
Tetrahedron 2004, 60, 1959–1982.
1d: R1 ) 2-HO-C6H4,
R2 ) Me
90 15 1o: R1 ) n-pent, R2 ) Me
96 16 1p: R-tetralone
86
90
99
95
1e: R1 ) 2-MeO-C6H4,
R2 ) Me
(3) Indium has been defined as a rare metal; thus catalysis is important: The
Elements, 3rd ed.; Emsley, J., Ed.; Oxford Press: Oxford, U.K., 1998.
(4) Selected examples for allylindium reagents: (a) Chan, T. H.; Yang, Y. J. Am.
Chem. Soc. 1999, 121, 3228–3229. (b) Lee, J. G.; Choi, K. I.; Pae, A. N.;
Koh, H. Y.; Kang, Y.; Cho, Y. S. J. Chem. Soc., Perkin Trans. 1 2002,
1314–1317. (c) Fontana, G.; Lubineau, A.; Scherrmann, M.-C. Org. Biomol.
Chem. 2005, 3, 1375–1380.
1f: R1 ) 4-Me-C6H4,
R2 ) Me
89 17 1q: ꢀ-tetralone
1g: R1 ) 1-naphthyl,
R2 ) Me
87 18 1r: R1 ) 2-thienyl, R2 ) Me
1h: R1 ) Ph,
R2 ) Et
95 19 1s: R1,2 ) -(CH2)2NBn(CH2)2- 88
(5) Reformatsky-type reagents: Babu, S. A.; Yasuda, M.; Shibata, I.; Baba, A.
Org. Lett. 2004, 6, 4475–4478.
(6) Selected examples for alkyl radical reagents: Account: Miyabe, H.; Naito,
T. Org. Biomol. Chem. 2004, 2, 1267-1270. (b) Shen, Z.-L.; Loh, T.-P.
Org. Lett. 2007, 9, 5413–5416.
1i: R1 ) Ph,
92 20 1t: R1 ) 4-pyridyl, R2 ) Me
97 21 1u: R1 ) 3-pyridyl, R2 ) Me
81
87
82
R2 ) n-Pr
(7) In contrast, In(III) complexes are commonly used in catalytic quantities as
Lewis acid catalysts: see ref 10c.
10 1j: R1 ) Ph(CH2)2,
R2 ) Me
11 1k: R1 ) 4-MeO-C6H4(CH2)2, 95 22 1v: R1 ) 2-furyl, R2 ) Me
R2 ) Me
(8) Catalytic use of In(0) for the preparation of “allylgallium” from allyl
bromide: (a) Takai, K.; Ikawa, Y. Org. Lett. 2002, 4, 1727–1729. (b) Takai,
K.; Ikawa, Y.; Ishii, K.; Kumanda, M. Chem. Lett. 2002, 172–173.
(9) Selected examples for the utility of the resulting tertiary homoallylic
alcohols: (a) Hayashi, S.; Hirano, K.; Yorimitsu, H.; Oshima, K. J. Am.
Chem. Soc. 2006, 128, 2210–2211. (b) Zhao, P.; Incarvito, C. D.; Hartwig,
J. F. J. Am. Chem. Soc. 2006, 128, 9642–9643. (c) Ohmura, T.; Furukawa,
H.; Suginome, M. J. Am. Chem. Soc. 2006, 128, 13366–13367.
(10) (a) Waltz, K. M.; Gavenonis, J.; Walsh, P. J. Angew. Chem., Int. Ed. 2002,
41, 3697–3699. (b) Yasuda, M.; Hirata, K.; Nishino, M.; Yamamoto, A.;
Baba, A. J. Am. Chem. Soc. 2002, 124, 13442–13447. (c) Key reference
for asymmetric In(III) catalysis: Lu, J.; Hong, M.-L.; Ji, S.-J.; Teo, Y.-C.;
Loh, T.-P. Chem. Commun. 2005, 4217–4218.
Table 2. In(0)-Catalyzed Formal R-Addition of 4 to Ketones 1 in
Water
(11) (a) Yamasaki, S.; Fujii, K.; Wada, R.; Kanai, M.; Shibasaki, M. J. Am.
Chem. Soc. 2002, 124, 6536–6537. (b) Wadamoto, M.; Yamamoto, H.
J.Am.Chem.Soc.2005,127,14556–14557.(c)Stoichiometricmethod:Burns,
N. Z.; Hackman, B. M.; Ng, P. Y.; Powelson, I. A.; Leighton, J. L. Angew.
Chem., Int. Ed. 2006, 45, 3811–3813.
(12) (a) Wada, R.; Oisaki, K.; Kanai, M.; Shibasaki, M. J. Am. Chem. Soc.
2004, 126, 8910–8911. (b) Lou, S.; Moquist, P. N.; Schaus, S. E. J. Am.
Chem. Soc. 2006, 128, 12660–12661.
entry
ketone 1
yield (%)
R/γ
syn-5/anti-5
1
2
3
4
5
6
1a: R1 ) Ph, R2 ) Me
99
93
90
75
72
91
>99:1
>99:1
>99:1
>99:1
>99:1
>99:1
58:1
32:1
1:65
84:1
32:1
40:1
1b: R1 ) 2-F-C6H4, R2 ) Me
1e: R1 ) 2-MeO-C6H4, R2 ) Me
1g: R1 ) 1-naphthyl, R2 ) Me
1p: R-tetralone
(13) Miller, J. J.; Sigman, M. S. J. Am. Chem. Soc. 2007, 129, 2752–2753.
(14) (a) Schneider, U.; Kobayashi, S. Angew. Chem., Int. Ed. 2007, 46, 5909–
5912. (b) Schneider, U.; Chen, I.-H.; Kobayashi, S. Org. Lett. 2008, 10,
737–740. (c) Kobayashi, S.; Konishi, H.; Schneider, U. Chem. Commun.
2008, 2313–2315. (d) Application of our In(I) catalysis: Selander, N.; Kipke,
A.; Sebelius, S.; Szabo´, K. J. J. Am. Chem. Soc. 2007, 129, 13723–13731.
(15) Review on low oxidation state In: Pardoe, J. A. J.; Downs, A. Chem. ReV.
2007, 107, 2–45.
1u: R1 ) 3-pyridyl, R2 ) Me
Scheme 2. Preliminary Study of Asymmetric In(0) Catalysis in Water
(16) No undesired compounds such as pinacol coupling type or reduction
products were detectable in the crude reaction mixtures.
(17) Proof of In(0) by SEM, EDS, ICP, and XFAS analyses (SI).
(18) Figure 1 shows the reaction system with 10 mol% of In powder before
reaction (left) and recovered In ingot after reaction (right). The recovered
ingot could be reused without loss of activity (SI).
(19) Optimized conditions: 1 (0.5 mmol), 2 (1.5 equiv), In(0) (3 mol%), H2O
(1 M), 30 °C, 24 h. Ga(0) as a catalyst proved to be much less effective
(low yield); the use of allylsilanes did not give any reaction.
(20) n-Hexane, toluene, THF, DCM, MeCN, DMF, MeNO2, DMSO, t-BuOH,
n-BuOH, i-PrOH, EtOH.
(21) In(I) readily decomposed upon contact with water to form In(0), which is
homoallylic alcohol 3a was isolated with 52% ee in 68% yield,
which is to the best of our knowledge the best result so far obtained
for catalytic asymmetric allylation of 1a in water. Other more
effective methods require strictly anhydrous conditions.10a,c,11-13
surmised to be the real catalyst;22 In(III) is stable in water.
(22) Kinetics and selectivity control experiments were also carried out (SI).
(23) Partial electron transfer from the oxygen lone pair of H2O to the In metal
surface may occur (Lewis base activation).
(24) Alternatively, water may be necessary for the stabilization of key
intermediates or the hydrolysis of the assumed O-B bond in the initially
formed allylborated ketone. The size, the H-bonding ability, and the proton
acidity of the solvent might be critical as well.
(25) Single electron transfer (SET) might be facilitated by the low first ionization
(26) Cf. Fujita, M.; Nagano, T.; Schneider, U.; Ogawa, C.; Kobayashi, S. J. Am.
Chem. Soc. 2008, 130, 2914–2915, See also ref 14c.
(27) Account on Lewis and Brønsted acid catalyzed allylboration of carbonyl
compounds: Hall, D. G. Synlett 2007, 1644–1655.
In conclusion, we have discovered an unprecedented catalytic use of
In(0) for C-C bond transformations. Remarkably, water is required for
these general allylations to proceed. Importantly, the In metal catalyst can
be recovered and reused without loss of activity. Moreover, the potential
of this concept has been demonstrated through highly regio- and diaste-
reoselective reactions and its applicability to asymmetric catalysis in water.
Further mechanistic studies on the catalytic activation of B reagents with
In(0) in water and the extension of this strategy to other catalytic bond
transformations will be reported in due course.
(28) Crotylboronates proved to be unreactive in the present reaction system.
(29) The anti-diastereoselectivity for substrate 1e (Table 2, entry 3) might be
explained with bidentate coordination of 1e to the crotylindium species (SI).
JA804182J
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J. AM. CHEM. SOC. VOL. 130, NO. 42, 2008 13825