Paper
Dalton Transactions
hexanes. Then the mixture of imine and ClSiMe2Ph was hydro-
lysed by adding 1 M HCl solution. The organic products (alde-
hyde and PhMe2SiOSiMe2Ph) were then extracted with CH2Cl2
and the solution was dried over MgSO4. In a representative
example of the reduction of F3CC6H4vN(i-Pr), 3-F3CC6H4CHO
was isolated by chromatography over silica using 15 : 1 hexane–
ethyl acetate as eluent to give the product as a colourless oil
(89 mg, 64% yield).
2001, 40, 2129; (b) K. Rangareddy, K. Selvakumar and
J. F. Harrod, J. Org. Chem., 2004, 69, 6843.
8 (a) A. C. Fernandes and C. C. Romão, J. Mol. Catal. A:
Chem., 2007, 272, 60; (b) R. Arias-Ugarte, H. K. Sharma,
A. L. C. Morris and K. H. Pannell, J. Am. Chem. Soc., 2012,
134, 848; (c) For reductive cleavage of the C–N bond, see:
S. Krackl, C. I. Someya and S. Enthaler, Chem. – Eur. J.,
2012, 18, 15267.
1H NMR (CH2Cl2): δ 10.02 (s, 1, CHO), 8.10 (s, 1, C6H4), 8.03
(d, J (H–H) = 8.15 Hz, 1, C6H4), 7.84 (d, J (H–H) = 8.15 Hz, 1,
C6H4), 7.64 (t, J (H–H) = 7.72 Hz, 1, C6H4). 19F NMR (CDCl3): δ
−62.94 (s, 1,3-CF3PhCHO). 1H–13C HSQC (CDCl3): δ 186.3
(CHO) 132.4 (C6H4), 131.0 (C6H4), 129.7 (C6H4), 126.5 (C6H4).
9 (a) Y. Sunada, H. Kawakami, T. Imaoka, Y. Motoyama and
H. Nagashima, Angew. Chem., Int. Ed., 2009, 48, 9511;
(b) S. Zhou, K. Junge, D. Addis, S. Das and M. Beller,
Angew. Chem., Int. Ed., 2009, 48, 9507; (c) A. Volkov,
E. Buitrage and H. Adolfsson, Eur. J. Org. Chem., 2013,
2066; (d) D. Bézier, G. T. Venkanna, J.-B. Sortais and
C. Darcel, ChemCatChem, 2011, 3, 1747.
10 (a) Y. Motoyama, K. Mitsui, T. Ishida and H. Nagashima,
J. Am. Chem. Soc., 2005, 127, 13150; (b) H. Sasakuma,
Y. Motoyama and H. Nagashima, Chem. Commun., 2007,
4916; (c) Y. Motoyama, S. Itonaga, T. Ishida, M. Takasaki
and H. Nagashima, Org. Synth., 2005, 82, 188.
Conclusions
We have developed a two-stage catalytic reduction of secondary
amides by silane HSiMe2Ph mediated by the Ru complex 1.
Alkyl and aryl amides bearing halogen, ketone, and ester
groups were converted with moderate to good yields to the 11 T. Dombray, C. Helleu, C. Darcel and J.-B. Sortais, Adv.
corresponding imines and aldehydes under mild reaction con- Synth. Catal., 2013, 355, 3358.
ditions. This procedure does not work for substrates bearing 12 (a) R. Kuwano, M. Takahashi and Y. Ito, Tetrahedron Lett.,
the nitro-group and fails for heteroaromatic amides. In the
case of cyano substituted amides, the cyano group is reduced
to imine.
1998, 39, 1017; (b) For earlier work, see: M. Igarashi
and T. Fuchikami, Tetrahedron Lett., 2001, 42, 1945;
(c) G. Gerona-Navarro, A. Bonache, M. Alías, J. Pérez de
Vega, T. García-López, P. López, C. Cativiela and
R. González-Muñiz, Tetrahedron Lett., 2004, 45, 2193.
13 S. Park and M. Brookhart, J. Am. Chem. Soc., 2012, 134, 640.
14 (a) L. I. Kopylova, N. D. Ivanova and M. G. Voronkov, Zh.
Obshch. Khim., 1985, 55, 1649; (b) S. Hanada, Y. Motoyama
and H. Nagashima, Tetrahedron Lett., 2006, 47, 6173;
(c) S. Hanada, E. Tsutsumi, Y. Motoyama and H. Nagashima,
J. Am. Chem. Soc., 2009, 131, 15032.
Acknowledgements
We are very grateful to Prof. J. Williams for inspiring discus-
sions. This work was supported by a DG NSERC grant to G.I.N.
We thank CIF and OIF for an equipment grant and
R. Simionescu for his help with NMR.
15 (a) S. Das, D. Addis, S. Zhou, K. Junge and M. Beller, J. Am.
Chem. Soc., 2010, 132, 1770; (b) S. Das, D. Addis, K. Junge
and M. Beller, Chem. – Eur. J., 2011, 17, 12186.
16 N. Sakai, K. Fujii and T. Konokahara, Tetrahedron Lett.,
2008, 49, 6873.
Notes and references
1 The Amide Linkage: Structural Significance in Chemistry, Bio-
chemistry, and Materials Science, ed. A. Greenberg, 17 (a) J. A. Fernández-Salas, S. Manzini and S. P. Nolan, Chem.
C. M. Breneman and J. F. Liebman, John Wiley & Sons,
New York, 2000.
Commun., 2013, 49, 9758; (b) W. Xie, M. Zhao and C. Cui,
Organometallics, 2013, 32, 7440.
2 (a) M. Hudlicky, Reductions in Organic Chemistry, ACS 18 Y. Li, J. A. Molina de La Torre, K. Grabow, U. Bentrup,
monograph, 1996, vol. 118; (b) Modern Reduction Methods,
ed. P. G. Andersson and I. J. Munslow, Wiley, NY, 2008.
K. Junge, S. Zhou, A. Brückner and M. Beller, Angew. Chem.,
Int. Ed., 2013, 52, 11577.
3 J. Seyden-Penne, Reduction by Alumino- and Borohydrides in 19 Related metal-free reduction of tertiary amides was accom-
Organic Synthesis, Wiley, NY, 2nd edn, 1997.
4 R. C. Larock, Comprehensive Organic Transformations: a
Guide to Functional Group Preparation, Wiley-VCH, NY, 2nd
edn, 1999.
5 N. Umino, T. Iwakuma and N. Itoh, Tetrahedron Lett., 1976,
17, 763.
plished with the Hantsch ester by using substrate pre-acti-
vation with Tf2O: G. Barbe and A. Charette, J. Am. Chem.
Soc., 2008, 130, 18.
20 (a) S. Hanada, T. Ishida, Y. Motoyama and H. Nagashima,
J. Org. Chem., 2007, 72, 7551; (b) H. Sasakuma,
Y. Motoyama and H. Nagashima, Chem. Commun., 2007,
4916; (c) For earlier work, see: E. Frainnet, A. Bazouin and
R. Calas, Compt. Rend., 1963, 257, 1304.
6 Advances in Silicon Science, in Hydrosilylation, ed. B. Marciniec,
Springer, 2009.
7 For reduction accompanied by C–C coupling, see: 21 S. Das, B. Join, K. Junge and M. Beller, Chem. Commun.,
(a) K. Selvakumar and J. F. Harrod, Angew. Chem., Int. Ed.,
2012, 48, 2683.
8892 | Dalton Trans., 2014, 43, 8888–8893
This journal is © The Royal Society of Chemistry 2014