ORGANIC
LETTERS
2008
Vol. 10, No. 3
521-524
Gold-Catalyzed [4+3]-Annulation of
Oxabicyclic Benzenes with 2-Substituted
Allylsilanes through Tandem Allylation
and Cyclization
Yu-Chia Hsu, Swarup Datta, Chun-Ming Ting, and Rai-Shung Liu*
Department of Chemistry, National Tsing-Hua UniVersity, Hsinchu, Taiwan, ROC
Received December 18, 2007
ABSTRACT
This work reports new gold-catalyzed [4
cyclization; on the basis of experimental observations, we propose a mechanism involving the opening of the oxacyclic ring by a PPh3Au -
assisted SN2-attack of allylsilanes.
+
3]-annulations of oxacyclic benzenes with 2-substituted allylsilanes through tandem allylation and
+
Additions of allylic organometallics to aldehydes, ketones,1
epoxides,2 and other oxacyclic electrophiles3 provide 1,n-
enols (n ) 4-6) efficiently, which have served widely as
building blocks for complicated bioactive molecules.1-3
Despite their great utility, these electrophiles react with
allylmetal species exclusively through a single-addition
pathway as depicted in eqs 1 and 2. We envisage that the
values of these reactions would become enhanced signifi-
cantly if these electrophiles undergo new annulation with
allylsilanes as depicted in eq 3. Although gold catalysis has
attained a substantial advance in the nucleophilic activations
of alkynes and alkenes,4,5 only limited examples have focused
on the activation of oxygen-containing electrophiles.6,7
Herein, we report an unprecedented gold-catalyzed [4 +
3]-annulation of oxabicyclic benzenes with allylsilanes
through a tandem allylation/cyclization route (eq 3). Before
this work, activations of oxabicyclic benzenes toward nu-
(1) (a) Chemler, S. R.; Roush, W. R. In Modern Carbonyl Chemistry;
Otera, J., Ed.; Wiley-VCH: Weinheim, Germany, 2000; Chapter 10. (b)
Denmark, S. E.; Almstead, N. G. In Modern Carbonyl Chemistry; Otera,
J., Ed.; Wiley-VCH: Weinheim, Germany, 2000; Chapter 11. (c) Ren, H.;
Dunet, G.; Mayer, P.; Knochel, P. J. Am. Chem. Soc. 2007, 129, 5376. (d)
Denmark, S. E.; Fu, J. Chem. ReV. 2003, 103, 2763. (e) Yamamoto, Y.;
Asao, N. Chem. ReV. 1993, 93, 2207. (f) Wadamoto, M.; Ozasa, N.;
Yanagisawa, A.; Yamamoto, H. J. Org. Chem. 2003, 68, 5593. (g) Kruger,
J.; Carreira, E. M. J. Am. Chem. Soc. 1998, 120, 837. (h) Gauthier, D. R.,
Jr.; Carreira, E. M. Angew. Chem. Int. Ed. 1996, 35, 2363. (i) Yasuda, M.;
Hirata, K.; Nishino, M.; Baba, A. J. Am. Chem. Soc. 2002, 124, 13442. (j)
Zhang, W.-C.; Li, C.-J. J. Org. Chem. 1999, 64, 3230.
(2) (a) Tanaka, T.; Inoue, T.; Kamei, K.; Murakami, K.; Iwata, C. J.
Chem. Soc., Chem. Commun. 1990, 906. (b) Reetz, M. T. Organotitanium
Reagents in Organic Synthesis; Springer: Berlin, 1986; pp 218. (c) Tanaka,
T.; Hiramatsu, K.; Kobayashi, Y.; Ohno, H. Tetrahedron 2005, 61, 6726.
(d) Overman, L. E.; Renhowe, P. A. J. Org. Chem. 1994, 59, 4138 and
references therein.
(4) (a) Hashmi, A. S. K. Chem. ReV. 2007, 107, 3180. (b) Fu¨rstner, A.;
Davies, P. W. Angew. Chem., Int. Ed. 2007, 46, 3410. (c) Gorin, D. J.;
Toste, F. D. Nature 2007, 446, 395. (d) Jime´nez-Nu´n˜ez, E.; Echavarren,
A. M. Chem. Commun. 2007, 333. (e) Kim, S. M.; Park, J. H.; Choi, S. Y.;
Chung, Y. K. Angew. Chem., Int. Ed. 2007, 46, 6172. (f) Li, G.; Zhung, L.
Angew. Chem., Int. Ed. 2007, 46, 5156. (g) Lian, J.-J.; Chen, P.-C.; Lin,
Y.-P.; Ting, H.-C.; Liu, R.-S. J. Am. Chem. Soc. 2006, 128, 11372.
(5) (a) Han, X.; Widenhoefer, R. A. Angew. Chem., Int. Ed. 2006, 45,
1747. (b) Yao, X.; Li, C.-J. J. Am. Chem. Soc. 2004, 126, 6884. (c) Zhang,
J.; Yang, C.-G.; He, C. J. Am. Chem. Soc. 2006, 128, 1798. (d) Liu, X.-Y.;
Li, C.-H.; Che, C.-M. Org. Lett. 2006, 8, 2707. (e) Xu, Q.; Imamura, Y.;
Fujiwara, M.; Souma, Y. J. Org. Chem. 1997, 62, 1594.
(6) (a) Schelwies, M.; Dempwolff, A. L.; Rominger, F.; Helmchen, G.
Angew. Chem., Int. Ed. 2007, 46, 5598. (b) Jime´nez-Nu´n˜ez, E.; Claverie,
C. K.; Nieto-Oberhuber, C.; Echavarren, A. M. Angew. Chem., Int. Ed.
2006, 45, 5452. (c) Lin, C.-C.; Teng, T.-M.; Odedra, A.; Liu, R.-S. J. Am.
Chem. Soc. 2007, 129, 3798. (d) Yao, X.; Li, C.-J. Org. Lett. 2006, 8, 1953.
(e) Kuninobu, Y.; Ishii, E.; Takai, K. Angew. Chem., Int. Ed. 2007, 46,
3296. (f) Georgy, M.; Boucard, V.; Campagne, J.-M. J. Am. Chem. Soc.
2005, 127, 14180.
(3) (a) Millward, D. B.; Sammis, G.; Waymouth, R. M. J. Org. Chem.
2000, 65, 3902. (b) Nakamura, M.; Matsuo, K.; Inoue, T.; Nakamura, E.
Org. Lett. 2003, 5, 1373. (c) Lautens, M.; Fagnou, K.; Hiebert, S. Acc.
Chem. Res. 2003, 36. 48. (d) Lautens, M.; Dockendorff, C.; Fagnou, K.;
Malicki, A. Org. Lett. 2002, 4, 1311. (e) Lautens, M.; Ma, S.; Chiu, P. J.
Am. Chem. Soc. 1997, 119, 6478.
10.1021/ol7030334 CCC: $40.75
© 2008 American Chemical Society
Published on Web 01/10/2008