Journal of the American Chemical Society
Communication
Scheme 3. Modifying Catalyst Design To Target Terminal
Alkenes
REFERENCES
■
(1) Beller, M.; Seayad, J.; Tillack, A.; Jiao, H. Angew. Chem., Int. Ed.
2004, 43, 3368.
(2) For a review of hydroamination, see: Muller, T. E.; Hultzsch, K.
̈
C.; Yus, M.; Foubelo, F.; Tada, M. Chem. Rev. 2008, 108, 3795 and
references therein.
(3) For a review of hydroaminoalkylation, see: Roesky, P. W. Angew.
Chem., Int. Ed. 2009, 48, 4892.
(4) For Ti catalysts, see: (a) Muller, C.; Saak, W.; Doye, S. Eur. J.
̈
Org. Chem. 2008, 2731. (b) Kubiak, R.; Prochnow, I.; Doye, S. Angew.
Chem., Int. Ed. 2009, 48, 1153. (c) Prochnow, I.; Kubiak, R.; Frey, O.
N.; Beckhaus, R.; Doye, S. ChemCatChem 2009, 1, 162. (d) Kubiak,
R.; Prochnow, I.; Doye, S. Angew. Chem., Int. Ed. 2010, 49, 2626.
a
b
Reaction conditions same as Table 1. Isolated yield.
(e) Prochnow, I.; Zark, P.; Muller, T.; Doye, S. Angew. Chem., Int. Ed.
̈
2011, 50, 6401. (f) Jaspers, D.; Saak, W.; Doye, S. Synlett 2012, 23,
However, the easily prepared and more sterically congested
complex 2, realizes full conversion to product 10 at only 110 °C
in 24 h. This result compares favorably with our known amidate
complex 5.6e These reactivity trends suggest that steric bulk/
congestion about the reactive metal center is required for
hydroaminoalkylation catalytic turnover. When working with
sterically less demanding terminal alkenes, more sterically
demanding ligand sets are required for efficient catalytic
turnover, while the more sterically accessible reactive complex
1 requires bulky substrates for good reactivity. Most
importantly, these results show how the easily varied ligand
environment of Ta can be used to advantage to prepare related
complexes to address complementary classes of substrates.
In summary, we have developed the first precatalyst for the
catalytic hydroaminoalkylation of unactivated, sterically de-
manding E- and Z-internal alkenes. Here we show that the
combination of sterically less demanding and electron-with-
drawing 2-pyridonate and chloride ligands on tantalum are
preferred for accommodating such bulky substrates. Complex 1
also exhibits good amine substrate scope and excellent
diastereoselectivities. Most importantly, these investigations
illustrate how the easily varied ligand environment of Ta can be
used to advantage in the design of mixed ligated complexes to
access improved substrate scope. On-going work focuses on
organometallic mechanistic investigations and catalyst develop-
ment efforts toward enantioselective and regioselective trans-
formations.
2098. (g) Dorfler, J.; Doye, S. Angew. Chem., Int. Ed. 2013, 52, 1806.
̈
(h) Preuß, T.; Saak, W.; Doye, S. Chem.Eur. J. 2013, 19, 3833.
(i) Chong, E.; Schafer, L. L. Org. Lett. 2013, 15, 6002.
(5) For Zr catalyst, see: Bexrud, J. A.; Eisenberger, P.; Leitch, D. C.;
Payne, P. R.; Schafer, L. L. J. Am. Chem. Soc. 2009, 131, 2116.
(6) For group 5 metal catalysts, see: (a) Clerici, M. G.; Maspero, F.
Synthesis 1980, 305. (b) Nugent, W. A.; Ovenall, D. W.; Holmes, S. J.
Organometallics 1983, 2, 161. (c) Herzon, S. B.; Hartwig, J. F. J. Am.
Chem. Soc. 2007, 129, 6690. (d) Herzon, S. B.; Hartwig, J. F. J. Am.
Chem. Soc. 2008, 130, 14940. (e) Eisenberger, P.; Ayinla, R. O.;
Lauzon, J. M. P.; Schafer, L. L. Angew. Chem., Int. Ed. 2009, 48, 8361.
(f) Eisenberger, P.; Schafer, L. L. Pure Appl. Chem. 2010, 82, 1503.
(g) Zi, G.; Zhang, F.; Song, H. Chem. Commun. 2010, 46, 6296.
(h) Zhang, F.; Song, H.; Zi, G. Dalton Trans. 2011, 40, 1547.
(i) Reznichenko, A. L.; Emge, T. J.; Audorsch, S.; Klauber, E. G.;
̈
Hultzsch, K. C.; Schmidt, B. Organometallics 2011, 30, 921.
(j) Reznichenko, A. L.; Hultzsch, K. C. J. Am. Chem. Soc. 2012, 134,
3300. (k) Payne, P. R.; Garcia, P.; Eisenberger, P.; Yim, J. C.-H.;
Schafer, L. L. Org. Lett. 2013, 15, 2182. (l) Garcia, P.; Payne, P. R.;
Chong, E.; Webster, R. L.; Barron, B. J.; Behrle, A. C.; Schmidt, J. A.
R.; Schafer, L. L. Tetrahedron 2013, 69, 5737. (m) Garcia, P.; Lau, Y.
Y.; Perry, M. R.; Schafer, L. L. Angew. Chem., Int. Ed. 2013, 52, 9144.
(n) Zhang, Z.; Hamel, J.-D.; Schafer, L. L. Chem.Eur. J. 2013, 19,
8751. (o) Dorfler, J.; Doye, S. Eur. J. Org. Chem. 2014, 2790.
̈
(7) Strained norbornene is the only internal alkene that has been
commonly reported to date.
(8) For Ru and Ir catalysts, see: (a) Jun, C.-H.; Hwang, D.-C.; Na, S.-
J. Chem. Commun. 1998, 1405. (b) Chatani, N.; Asaumi, T.; Yorimitsu,
S.; Ikeda, T.; Kakiuchi, F.; Murai, S. J. Am. Chem. Soc. 2001, 123,
10935. (c) Pan, S.; Endo, K.; Shibata, T. Org. Lett. 2011, 13, 4692.
(d) Pan, S.; Matsuo, Y.; Endo, K.; Shibata, T. Tetrahedron 2012, 68,
ASSOCIATED CONTENT
■
́
9009. (e) Bergman, S. D.; Storr, T. E.; Prokopcova, H.; Aelvoet, K.;
S
* Supporting Information
Diels, G.; Meerpoel, L.; Maes, B. U. W. Chem.Eur. J. 2012, 18,
10393. (f) Schmitt, D. C.; Lee, J.; Dechert-Schmitt, A.-M. R.;
Yamaguchi, E.; Krische, M. J. Chem. Commun. 2013, 49, 6096.
(g) Schinkel, M.; Wang, L.; Bielefeld, K.; Ackermann, L. Org. Lett.
2014, 16, 1876.
Experimental procedures, compound characterization (1H and
13C NMR spectra), and crystallographic data (CIF). This
material is available free of charge via the Internet at http://
(9) (a) Atinolo, A.; Carrillo-Hermosilla, F.; Fernan
́
dez-Baeza, J.;
dez de Toro, A. M.; García-Yuste, S.; Otero, A.; Perez-Flores, J.
C.; Rodríguez, A. M. Inorg. Chim. Acta 2000, 300, 131. (b) Fandos, R.;
Hernandez, C.; Otero, A.; Rodríguez, A.; Ruiz, M. J.; Terreros, P. Eur.
̃
Fernan
́
́
AUTHOR INFORMATION
Corresponding Author
■
́
J. Inorg. Chem. 2003, 493. (c) Nagy, S.; Cribbs, L. V.; Etherton, B. P.;
Cocoman, M.; Krishnamurti, R.; Tyrell, J. A. U.S. Patent 6,759,493 B1,
July 6, 2004.
Notes
The authors declare no competing financial interest.
(10) See Supporting Information.
(11) In the reaction of 1 and an excess of E-3-hexene (no amine
substrate), dialkylation of dimethylamido ligands was observed,6n but
no CC bond isomerization was observed with the remaining E-3-
hexene.
(12) Longer reaction times do not significantly improve the yield.
(13) Attempts to react other N-heterocycles, such as pyrrolidine,
piperidine, and N-substituted piperazines, with E-3-hexene have been
unsuccessful.
ACKNOWLEDGMENTS
■
Dedicated to Dr. Howard C. Clark, Professor of Chemistry at
the University of British Columbia from 1957−1965. The
authors thank NSERC for financial support of this work and
postgraduate scholarships to E.C. and J.W.B. We thank Jacky
C.-H. Yim (UBC) for assistance with X-ray crystallography.
This research was undertaken, in part, thanks to funding from
the Canada Research Chairs program.
10901
dx.doi.org/10.1021/ja506187m | J. Am. Chem. Soc. 2014, 136, 10898−10901