ORGANIC
LETTERS
2011
Vol. 13, No. 23
6236–6239
Gaining Absolute Control of the
Regiochemistry in the Cobalt-Catalyzed
1,4-Hydrovinylation Reaction
†
Marion Arndt, Mehmet Dindaroglu, Hans-Gunther Schmalz, and Gerhard Hilt*
‡
‡
,†
ꢀ
€
€
Fachbereich Chemie, Philipps-Universitat Marburg, Hans-Meerwein-Str., 35043
€
€
Marburg, Germany, and Department fu€r Chemie, Universitat zu Koln, Greinstr. 4,
50939 Cologne, Germany
Received October 7, 2011
ABSTRACT
The absolute control of the regiochemistry of a cobalt-catalyzed 1,4-hydrovinylation reaction is achieved by alternation of the ligands applied.
While the dppe/dppp ligands led to the formation of the branched product, the herein described application of the SchmalzPhos ligand generates
the corresponding linear product in both excellent yields and regioselectivities. The catalyst system exhibits a high tolerance toward functional
groups, and the very mild reaction conditions allow the synthesis of 1,4-dienes without isomerization into conjugated systems.
The control of the regiochemistry of organic transfor-
mations is a great challenge for organic chemists in acade-
mia as well as in industry.1 Regiocontrol can be achieved in
many cases by employing selectively functionalized start-
ing materials, e.g. in transition metal catalyzed cross-
coupling reactions where the sites of the halide and metal
groups determine the product constitution. In atom economic
transformations of olefins, for instance in cobalt-catalyzed
cycloaddition reactions, good levels of regioselectivity can
often be achieved by a proper choice of ligands.2 In certain
cases it is even possible to selectively synthesize two different
products from the same starting material.
a formal 1,4-hydrovinylation3 inspired us to search for
alternative ligands eventually inducing the formation of
the regioisomeric hydrovinylation products. Our first gen-
eration of catalyst system A [CoBr2(dppe), Zn, ZnI2] ap-
plied in the 1,4-hydrovinylation of a terminal alkene (1) with
(3) (a) Hilt, G.; Roesner, S. Synthesis 2011, 662. (b) Arndt, M.;
Reinhold, A.; Hilt, G. J. Org. Chem. 2010, 75, 5203. (c) Hilt, G.; Arndt,
M.; Weske, D. F. Synthesis 2010, 1321. (d) Kersten, L.; Roesner, S.; Hilt,
€
G. Org. Lett. 2010, 12, 4920. (e) Hilt, G.; Luers, S.; Schmidt, F. Synthesis
€
2004, 634. (f) Hilt, G.; Luers, S. Synthesis 2002, 609. (g) Hilt, G.; du
€
Mesnil, F.-X.; Luers, S. Angew. Chem., Int. Ed. 2001, 40, 387. For 1,2-
hydrovinylation reactions, see: (h) Sharma, R. K.; RajanBabu, T. V.
J. Am. Chem. Soc. 2010, 132, 3295. (i) Saha, B.; Smith, C. R.; RajanBabu,
T. V. J. Am. Chem. Soc. 2008, 130, 9000. (j) Shirakura, M.; Suginome, M.
J. Am. Chem. Soc. 2008, 130, 5410. (k) Saha, B.; RajanBabu, T. V. J. Org.
The recent application of cobalt catalysis in the synthesis
of acyclic 1,4-dienes (and some follow-up products) through
ꢁ
Chem. 2007, 72, 2357. (l) Lassauque, N.; Francio, G.; Leitner, W. Adv.
ꢁ
Synth. Catal. 2009, 351, 3133. (m) Lassauque, N.; Francio, G.; Leitner, W.
€
Eur. J. Org. Chem. 2009, 3199. (n) Grutters, M. M. P.; Muller, C.; Vogt,
†
€
Philipps-Universitat Marburg.
D. J. Am. Chem. Soc. 2006, 128, 7414.
(4) For a very recent application of the SchmalzPhos ligand, see:
‡
€
€
Universitat zu Koln.
(1) (a) Kumar, R. R.; Kagan, H. B. Adv. Synth. Catal. 2010, 352, 231.
(b) Dehli, J. R.; Gotor, V. Chem. Soc. Rev. 2002, 31, 365. (c) Bausch,
C. C.; Patman, R. L.; Breit, B.; Krische, M. J. Angew. Chem., Int. Ed.
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Org. Lett. 2010, 12, 5418. (e) Wu, B.; Parquette, J. R.; RajanBabu, T. V.
Science 2009, 326, 1662. (f) Jana, C. K.; Studer, A. Angew. Chem., Int.
ꢀ
(a) Bohn, M. A.; Schmidt, A.; Hilt, G.; Dindaroglu, M.; Schmalz, H.-
G. Angew. Chem., Int. Ed. 2011, 50, 9689. See also: (b) Kranich, R.; Eis,
K.; Geis, O.; Muhle, S.; Bats, J. W.; Schmalz, H.-G. Chem.;Eur. J. 2000,
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H.-G.; Reek, J. N. H. Organometallics 2010, 29, 478. (g) Robert, T.; Abiri,
Z.; Sandee, A. J.; Schmalz, H.-G.; Reek, J. N. H. Tetrahedron:Asymmetry
€
€
€
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Chem.;Eur. J. 2007, 13, 8084. (h) Pineschi, M.; Del Moro, F.; Crotti, P.;
Di Bussolo, V.; Macchia, F. J. Org. Chem. 2004, 69, 2099. (i) Tanaka, K.;
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(2) (a) Hilt, G.; Janikowski, J. Org. Lett. 2009, 11, 773. (b) Hilt, G.;
Janikowski, J.; Hess, W. Angew. Chem., Int. Ed. 2006, 45, 5204.
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r
10.1021/ol202696n
Published on Web 10/31/2011
2011 American Chemical Society