ChemComm
Communication
4 For C–O bond formation: (a) L. Chen, E. Shi, Z. Liu, S. Chen, W. Wei,
H. Li, K. Xu and X. Wan, Chem. – Eur. J., 2011, 17, 4085; (b) W. Wei,
C. Zhang, Y. Xu and X. Wan, Chem. Commun., 2011, 47, 10827;
(c) Q. Xue, J. Xie, P. Xu, K. Hu, Y. Cheng and C. Zhu, ACS Catal.,
2013, 3, 1365; (d) W. Wang, J. Xue, T. Tian, J. Zhang, L. Wei, J. Shao,
Z. Xie and Y. Li, Org. Lett., 2013, 15, 2402; (e) C. Zhu and Y. Wei,
ChemSusChem, 2011, 8, 1082.
5 For C–N bond formation: (a) T. Froehr, C. P. Sindlinger,
U. Kloeckner, P. Finkbeiner and B. J. Nachtsheim, Org. Lett., 2011,
13, 3754; (b) L. Ma, X. Wang, W. Yu and B. Han, Chem. Commun.,
2011, 47, 11333; (c) Y. Lv, Y. Li, T. Xiong, Q. Liu and Q. Zhang, Chem.
Commun., 2014, 50, 2367.
6 For C–C bond formation: (a) A. Rodrguez and W. J. Moran, Org. Lett.,
2011, 13, 2220; (b) Y.-C. Wong, C.-T. Tseng, T.-T. Kao, Y.-C. Yeh and
K.-S. Shia, Org. Lett., 2012, 14, 6024.
7 (a) S. M. Johnson, S. Connelly, I. A. Wilson and J. W. Kelly, J. Med.
Chem., 2008, 51, 260; (b) A. D. Rodriguez, C. Ramirez, I. Rodriguez and
E. Gonzalez, Org. Lett., 1999, 1, 527; (c) J. P. Davidson and E. J. Corey,
J. Am. Chem. Soc., 2003, 125, 13486; (d) M. Ueki, K. Ueno, S. Miyadoh,
K. Abe, K. Shibata, M. Taniguchi and S. Oi, J. Antibiot., 1993, 46, 1089;
(e) S. Park, S. Kim, J. Seo and S. Y. Park, Macromolecules, 2005,
38, 4557; ( f ) H. Razavi, S. K. Palaninathan, E. T. Powers,
R. L. Wiseman, H. E. Purkey, N. N. Mohamedmohaideen,
S. Deechongkit, K. P. Chiang, M. T. A. Dendle, J. C. Sacchettini and
J. W. Kelly, Angew. Chem., Int. Ed., 2003, 42, 2758.
8 (a) D. L. Boger, H. Sato, A. E. Lerner, M. P. Hedrick, R. A. Fecik,
H. Miyauchi, G. D. Wilkie, B. J. Austin, M. P. Patricelli and
B. F. Cravatt, Proc. Natl. Acad. Sci. U. S. A., 2000, 97, 5044;
(b) M. Seierstad and J. G. Breitenbucher, J. Med. Chem., 2008,
51, 7327; (c) M. E. Mcgrath, P. A. Sprengeler, C. M. Hill,
V. Martichonok, H. Cheung, J. R. Somoza, J. T. Palmer and
J. W. Janc, Biochemistry, 2003, 42, 15018; (d) D. C. Tully, A. Vidal,
A. K. Chatterjee, J. A. Williams, M. J. Roberts, H. M. Petrassi,
G. Sparggon, B. Bursulaya, R. Pacoma, A. Shipway,
A. M. Schumacher, H. Danahay and J. L. Harris, Bioorg. Med. Chem.
Lett., 2008, 51, 23; (e) B. E. Maryanoff and M. J. Costanzo, Bioorg.
Med. Chem., 2008, 16, 1562; ( f ) M. J. Myllymakiki, S. M. Saario,
A. O. Kataja, J. A. Castillo-Melendez, T. Nevalainen, R. O. Juvonen,
T. Jarvinen and A. M. P. Koskinen, J. Med. Chem., 2007, 50, 4236.
9 (a) N. K. Harn, C. J. Gramer and B. A. Anderson, Tetrahedron Lett.,
1995, 36, 9453; (b) P. Lassalas, F. Marsais and C. Hoarau, Synlett,
2013, 2233; (c) Q. Y. Toh, A. McNally, S. Vera, N. Erdmann and
M. J. Gaunt, J. Am. Chem. Soc., 2013, 135, 3772; (d) X.-F. Wu,
P. Anbarasan, H. Neumann and M. Beller, Angew. Chem., Int. Ed.,
2010, 49, 7316; (e) X. Fan, Y. He, X. Zhang, S. Guo and Y. Wang,
Tetrahedron, 2011, 67, 6369; ( f ) S. Sharma, I. A. Khan and
A. K. Saxena, Adv. Synth. Catal., 2013, 355, 673.
Scheme 3 Proposed catalytic pathway.
and regenerates the catalyst for the next cycle.12 Finally, inter-
mediate E undergoes detosylation in the presence of base to
give the final product 2.
In conclusion, we have demonstrated a practical one-pot
approach to prepare a-ketobenzoxazoles under mild and tran-
sition metal-free conditions. Moreover, the key features of
this work include an inexpensive catalytic system, exceptional
functional group tolerance, easily accessible starting materials,
and scalability. Studies on evaluation of biological activity of
synthesized compounds and further investigations to extend
the strategy to various useful heterocycles are now underway.
The authors gratefully acknowledge the Ministry of Science
and Technology (MOST), Taiwan for financial support.
Notes and references
1 (a) P. J. Stang and V. V. Zhdankin, Chem. Rev., 1996, 96, 1123;
(b) V. V. Zhdankin and P. J. Stang, Chem. Rev., 2008, 108, 5299;
(c) E. A. Merritt and B. Olofsson, Angew. Chem., Int. Ed., 2009,
48, 9052; (d) M. Kirihara, Y. Asai, S. Ogawa, T. Noguchi, A. Hatano 10 A series of starting materials (1a–1u) were synthesized in moderate
and Y. Hirai, Synthesis, 2007, 3286.
2 (a) M. Uyanik, H. Okamoto, T. Yasui and K. Ishihara, Science, 2010,
to good yields (41–71%). For experimental procedures, please see
the ESI†.
328, 1376; (b) M. Uyanik, T. Yasui and K. Ishihara, Angew. Chem., Int. 11 CCDC 991635 (2s) contains the supplementary crystallographic data
Ed., 2010, 49, 2175. for this paper.
3 (a) M. Uyanik and K. Ishihara, ChemCatChem, 2012, 4, 177; 12 The intermediate ‘‘E’’ can be isolable in the absence of base (see the
(b) P. Fenkbeiner and B. J. Nachtsheim, Synthesis, 2013, 979.
ESI†).
This journal is ©The Royal Society of Chemistry 2014
Chem. Commun.