Organometallics
Communication
Finally, it appears to be difficult to correlate the redox potential
(g) Flowers, R. A., II Synlett 2008, 1427−1439. (h) Nicolaou, K. C.;
Ellery, S. P.; Chen, J. S. Angew. Chem. 2009, 121, 7276−7301.
with the reactivity of electrogenerated SmX . However, we have
2
(i) Szostak, M.; Procter, D. J. Angew. Chem., Int. Ed. 2011, 50, 7737−
highlighted that when SmX reagent sare prepared in the
2
7
2
(
739. (j) Beemelmanns, C.; Reissig, H. U. Chem. Soc. Rev. 2011, 40,
199−2210. (k) Harb, H. Y.; Procter, D. J. Synlett 2012, 23, 6−20.
presence of nBu NPF , their reactivity significantly increases and
4
6
remains equivalent for all divalent samarium derivatives. The
supporting electrolyte, thought to be innocent, is in fact a key
3) (a) Namy, J. L.; Girard, P.; Kagan, H. B. Nouv. J. Chim. 1977, 1, 5−
7
. (b) Girard, P.; Namy, J. L.; Kagan, H. B. J. Am. Chem. Soc. 1980, 102,
additive for increasing the reactivity of SmX derivatives studied.
2
2693−2698.
In summary, SmBr , SmCl , and Sm(OTf) complexes were
2
2
2
(4) (a) Bochkarev, M. N. Coord. Chem. Rev. 2004, 248, 835−851.
(b) Evans, W. J. Inorg. Chem. 2007, 46, 3435−3449. (c) Meyer, G.
Angew. Chem., Int. Ed. 2008, 47, 4962−4964. (d) Nief, F. Dalton Trans.
2010, 39, 6589−6598. (e) Procter, D. J.; Szostak, M. Angew. Chem., Int.
Ed. 2012, 51, 9238−9256. (f) Choquette, K. A.; Flowers, R. A. Sm and
Yb Reagents. In Comprehensive Organic Synthesis, 2nd ed.; Molander, G.
A., Knochel, P., Eds.; Elsevier: Oxford, U.K., 2014; Vol. 1, pp 279−343.
synthesized in one step thanks to the use of a sacrificial samarium
anode. This electrosynthetic procedure avoids the presence of
additional metals such as Li and Mg. The combination of a
soluble samarium anode and n-Bu NX salts (X = Cl, Br, OTf) as
4
ligand sources proves to be very reliable for the preparation of
complexes well characterized by electrochemistry and UV−vis
spectroscopy. Attempts to correlate their redox potentials with
their reactivities in the reduction of a recalcitrant substrate such
as 1-chlorododecane showed unexpected results. Additional
(
5) Lebrun, A.; Namy, J. L.; Kagan, H. B. Tetrahedron Lett. 1993, 34,
311−2314.
6) (a) Hel
4, 5507−5510. (b) Dahlen
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2
(
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ion, F.; Lannou, M. I.; Namy, J. L. Tetrahedron Lett. 2003,
, A.; Hilmersson, G. Eur. J. Inorg. Chem.
4
́
experiments demonstrated that the presence of nBu NPF6
4
during the synthesis of Sm(II) complexes is responsible for the
observed increase in reactivity. What is particularly interesting is
that it is only when the nBu NPF was present during the
(7) Miller, R. S.; Sealy, J. M.; Shabangi, M.; Kuhlman, M. L.; Fuchs, J.
R.; Flowers, R. A., II J. Am. Chem. Soc. 2000, 122, 7718−7722.
(8) Fuchs, J. R.; Mitchell, M. L.; Shabangi, M.; Flowers, R. A., II
Tetrahedron Lett. 1997, 38, 8157−8158.
4
6
formation of the SmI complex that reactivity was observed,
2
(9) (a) Matsukawa, S.; Ichikawa, K.; Ogura, Y. Synth. Commun. 2010,
which leads us to assume that the initial structure of the complex
was probably changed, favoring electrostatic interactions needed
for the substrate activation. This ammonium salt effect opens up
very interesting prospects in the field of samarium divalent
reductants, and work is ongoing to understand the mechanism
and to evaluate this effect on more challenging substrates.
4
0, 1345−1349. (b) Matsukawa, S.; Hinakubo, Y. Org. Lett. 2003, 5,
1
(
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10) Rossmanith, K. Monatsh. Chem. 1979, 110, 109−114.
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(
1
(
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981−1984. (b) Fukuzawa, S.; Mutoh, K.; Tsuchimoto, T.; Hiyama, T. J.
Org. Chem. 1996, 61, 5400−5405.
13) (a) Teprovich, J. A., Jr.; Antharjanam, P. K. S.; Prasad, E.;
Pesciotta, E. N.; Flowers, R. A., II Eur. J. Inorg. Chem. 2008, 5015−5019.
b) Maisano, T.; Tempest, K. E.; Sadasivam, D. V.; Flowers, R. A., II Org.
ASSOCIATED CONTENT
Supporting Information
■
*
S
(
Text, figures, and tables giving detailed experimental procedures,
UV−vis analysis, electrochemical analysis, and additional
(
Biomol. Chem. 2011, 9, 1714−1716. See also: (a) Mashima, K.; Oshiki,
T.; Tani, K. J. Org. Chem. 1998, 63, 7114−7116. (b) Collin, J.;
Giuseppone, N.; Machrouhi, F.; Namy, J. L.; Nief, F. Tetrahedron Lett.
1
999, 40, 3161−3164.
AUTHOR INFORMATION
Corresponding Author
■
(14) Gilles, P.; Py, S. Org. Lett. 2012, 14, 1042−1045.
(15) Bond, A. M.; Deacon, G. B.; Newnham, R. H. Organometallics
1986, 5, 2312−2316.
(
16) Evans, W. J.; Gonzales, S. L.; Ziller, J. W. J. Am. Chem. Soc. 1994,
1
(
16, 2600−2608.
Notes
17) (a) Sahloul, K.; Sun, L.; Requet, A.; Chahine, Y.; Mellah, M. Chem.
The authors declare no competing financial interest.
Eur. J. 2012, 18, 11205−11209. (b) Sun, L.; Sahloul, K.; Mellah, M. ACS
Catal. 2013, 3, 2568−2573.
ACKNOWLEDGMENTS
We thank the University Paris-Sud and the CNRS for their
financial support.
■
(18) Shabangi, M.; Sealy, J. M.; Fuchs, J. R.; Flowers, R. A., II
Tetrahedron Lett. 1998, 39, 4429−4432.
(
(
19) Knettle, B. W.; Flowers, R. A., II Org. Lett. 2001, 3, 2321−2324.
20) Inanaga, J.; Ishikawa, M.; Yamaguchi, M. Chem. Lett. 1987, 1485−
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486.
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