Chemistry Letters 2002
13
group of 21 was also partially cleaved affording an equilibrium
mixture of keto alcohol 23 and its hemiacetal in 20% yield along
with major product 22 in 71% yield. Hydrolysis of 24 is a slow
reaction and it required 48 h even by using 0.2eq of catalyst to
give ketone 25 (83% yield) along with keto alcohol 26 in 10%
yield.
(1963).
2H. Schick, B. Roatsch, S. Schramm, H. -D. Gilsing, M.
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3
4
When the reaction of 6-acetoxyhexyne (13) with 0.05 eq of
Hg(OTf)2Á(TMU)2 and 3 eq of H2O in CD3CN was monitored by
400 MHz NMR, we detected only the decrease of the starting 13
and increase of ketone 14, reflecting the slow but very clean
reaction. Thus the procedure is simple enough to apply to medium
scale synthesis. Following is a challenge to prepare unstable
benzyl methyl ketone (4) in a gram scale by using 1 mol% of
catalyst. A solution of Hg(OTf)2Á(TMU)2 prepared by mixing
HgO (40 mg, 0.19 mmol) and Tf2O (52mg, 0.19 mmol), and
then TMU (43 mg, 0.38 mmol) in acetonitrile (10 mL) was
added to 3-phenyl-1-propyne (3) (2.15 g, 19 mmol). After
addition of H2O (1 g, 57 mmol) and then dichloromethane
(4 mL), the resulting nearly-homogeneous mixture was stirred at
room temperature for 24 h. An aqueous sodium hydrogenecar-
bonate-sodium chloride solution was added and the organic
material were extracted with ethyl acetate. Dried and concen-
trated material was purified through short pass column chroma-
tography on silica gel by using hexane and ethyl acetate to give 4
(2.42 g, 97% yield).
5
6
Y. Fukuda and K. Uchimoto, J. Org. Chem., 56, 3729 (1991).
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Mercuric triflate is instantaneously prepared in situ by mixing
yellow mercuric oxide and triflic anhydride in CH3CN at
room temperature. see M. Nishizawa, E. Morikuni, K. Asoh,
Y. Kan, K. Uenoyama, and H. Imagawa, Synlett, 1995, 169.
7
8
9
10 a) M. Nishizawa, H. Takenaka, and Y. Hayashi, J. Org.
Chem., 51, 806 (1986). b) M. Nishizawa, H. Yamada, and Y.
Hayashi, J. Org. Chem., 52, 4878 (1987). c) M. Nishizawa, H.
Takao, Y. Iwamoto, H. Yamada, and H. Imagawa, Synlett,
1998, 76. d) M. Nishizawa, H. Imagawa, I. Hyodo, M. Takeji,
E. Morikuni, K. Asoh, and H. Yamada, Tetrahedron Lett., 39,
389 (1989).
11 N. J. Newcombe, F. Ya, R. J. Vijn, H. Hiemstra, and W. N.
Speckamp, J. Chem. Soc., Chem. Commun., 1994, 767.
12H. Imagawa, T. Shigaraki, T. Suzuki, H. Takao, H. Yamada,
T. Sugihara, and M. Nishizawa, Chem. Pharm. Bull., 46, 1341
(1998); M. Nishizawa, T. Kashima, M. Sakakibara, A.
Wakabayashi, K. Takahashi, H. Takao, H. Imagawa, and T.
Sugihara, Heterocycles, 54, 629 (2001).
This research was supported by a Grant-in-Aid for Scientific
Research on Priority Areas (A) ‘‘Exploitation of Multi-Element
Cyclic Molecules’’ from the Ministry of Education, Culture,
Sports, Science and Technology, Japan.
Dedicated to Professor Teruaki Mukaiyama on the occasion
of his 75th birthday.
13 M. Nishizawa, T. Shigaraki, H. Takao, H. Imagawa, and T.
Sugihara, Tetrahedron Lett., 40, 1153 (1999).
References and Notes
1
14 The addition of a large quantity of CH2Cl2 caused Hg(OTf)2
to precipitate.
G. W. Stacy and R. A. Mikulec, Org. Syn., Coll. Vol. IV, 13