ORGANIC
LETTERS
2011
Vol. 13, No. 23
6192–6195
Dialkylaluminum Hydride-Promoted
Cyclodimerization of Silylated 1,3-Enynes
via Skeletal Rearrangement
Hidenori Kinoshita, Tomoyuki Ishikawa, and Katsukiyo Miura*
Department of Applied Chemistry, Graduate School of Science and Engineering,
Saitma University, 255 Shimo-ohkubo, Sakura-ku, Saitama 338-8570, Japan
Received September 26, 2011
ABSTRACT
The dialkylaluminum hydride-promoted reaction of 1-silylalk-3-en-1-ynes gave symmetrical 1,2,3,5-tetrasubstituted benzenes as single regioisomers. The
novel cyclodimerization via skeletal rearrangement can be rationalized by an unprecedented mechanism involving sequential hydroalumination, alkene
isomerization, carboalumination, carbonꢀcarbon bond cleavage, and retro-hydroalumination.
Regio-controlled synthesis of multisubstituted benzenes
is one of the central fields in synthetic organic chemistry
because polysubstituted arenes are ubiquitous units in func-
tional molecular materials and biologically active com-
pounds.1,2 Sequential substitution on existing benzene rings
is a conventional way of dealing with this subject. However,
this strategy is often accompanied by the problems of incom-
plete regio-selectivity, difficulty in direct introduction of
desired substituents, and low efficiency of the linear multistep
approach. For the last few decades, much attention has been
focused on transition metal-catalyzed cycloaddition of two
or more components, which enables a convergent, efficient
approach to multisubstituted benzenes. So far [2 þ 2 þ 2]
cycloaddition of two or three kinds of alkynes has been
studied intensively.3 Highly selective construction of
multisubstituted benzenes by this method appears in
recent reports, although the scope is still rather limited.4 1,
3-Enynes and 1,3-dicarbonyl compounds as well as alkynes
serve as the components for benzene ring construction.5ꢀ7
Yamamoto, Gevorgyan, and co-workers have demon-
strated that Pd-catalyzed cyclodimerization of 1,3-
enynes and cycloaddition of 1,3-enynes to alkynes form
(4) (a) Tanaka, K.; Shirasaka, K. Org. Lett. 2003, 5, 4697.
(b) Yamamoto, Y.; Ishii, J.; Nishiyama, H.; Itoh, K. J. Am. Chem.
Soc. 2004, 126, 3712. (c) Yamamoto, Y.; Ishii, J.; Nishiyama, H.; Itoh,
K. J. Am. Chem. Soc. 2005, 127, 9625. (d) Saino, N.; Amemiya, F.;
Tanabe, E.; Kase, K.; Okamoto, S. Org. Lett. 2006, 8, 1439. (e) Hara, H.;
Hirano, M.; Tanaka, K. Org. Lett. 2008, 10, 2537.
(5) Pd-catalyzed cyclodimerization of 1,3-enynes: (a) Saito, S.; Salter,
M. S.; Gevorgyan, V.; Tsuboya, N.; Tando, K.; Yamamoto, Y. J. Am.
Chem. Soc. 1996, 118, 3970. (b) Xi, C.; Chen, C.; Lin, J.; Hong, X. Org.
Lett. 2005, 7, 347.
(6) Pd-catalyzed cycloaddition of 1,3-enynes to alkynes: (a) Gevorgyan,
V.; Takeda, A.; Yamamoto, Y. J. Am. Chem. Soc. 1997, 119, 11313.
(b) Gevorgyan, V.; Takeda, A.; Homma, M.; Sadayori, N.; Radhakrishnan,
V.; Yamamoto, Y. J. Am. Chem. Soc. 1999, 121, 6391. (c) Gevorgyan, V.;
Radhakrishnan, U.; Takeda, A.; Rubina, M.; Rubin, M.; Yamamoto, Y.
J. Org. Chem. 2001, 66, 2835. (d) Rubin, M.; Sromek, A. W.; Gevorgyan, V.
Synlett 2003, 2265. (e) Rubina, M.; Conley, M.; Gevorgyan, V J. Am. Chem.
Soc. 2006, 128, 5818.
(7) Regioselective synthesis of multisubstituted benzenes from
alkynes and 1,3-dicarbonyl compounds with Re or Mn catalysts:
(a) Kuninobu, Y.; Nishi, M.; Yudha, S.; Takai, K. Org. Lett. 2008, 10,
3009. (b) Kuninobu, Y.; Takata, H.; Kawata, A.; Takai, K. Org. Lett.
2008, 10, 3133. (c) Yoshikai, N.; Zhang, S.-L.; Yamagata, K.; Tsuji, H.;
Nakamura, E. J. Am. Chem. Soc. 2009, 131, 4099.
(1) For example, see the following book: Perepichka, D. F.; Perepichka,
I. F.; Meng, H.; Wudl, F. Organic Light-Emitting Materials and Devices;
Taylor & Francis: Boca Raton, FL, 2007.
(2) Scott, A. I.; Devon, T. K. Handbook of Naturally Occurring
Compounds; Academic Press: New York, 1972.
(3) (a) Vollhardt, K. P. C. Angew. Chem., Int. Ed. Engl. 1984, 23, 539.
(b) Schore, N. E. In Comprehensive Organic Synthesis; Trost, B. M., Fleming,
I., Eds.; Pergamon Press: New York, 1991; Vol. 5, p 1129. (c) Lautens, M.;
Klute, W.; Tam, W. Chem. Rev. 1996, 96, 49. (d) Saito, S.; Yamamoto, Y.
Chem. Rev. 2000, 100, 2901.
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10.1021/ol202601s
Published on Web 11/01/2011
2011 American Chemical Society