Journal of the American Chemical Society
Communication
Ru(II) complexes, see: (b) Balaraman, E.; Gunanathan, C.; Zhang, J.;
Shimon, L. J. W.; Milstein, D. Nat. Chem. 2011, 3, 609. (c) Balaraman,
E.; Ben-David, Y.; Milstein, D. Angew. Chem., Int. Ed. 2011, 50, 11702.
(7) (a) Ito, M.; Koo, L. W.; Himizu, A.; Kobayashi, C.; Sakaguchi, A.;
Ikariya, T. Angew. Chem., Int. Ed. 2009, 48, 1324. (b) Ito, M.; Ootsuka,
T.; Watari, R.; Shiibashi, A.; Himizu, A.; Ikariya, T. J. Am. Chem. Soc.
2011, 133, 4240. For a review, see: (c) Dub, P. A.; Ikariya, T. ACS Catal.
2012, 2, 1718.
ASSOCIATED CONTENT
* Supporting Information
Experimental procedures and compound characterization data.
This material is available free of charge via the Internet at http://
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S
AUTHOR INFORMATION
Corresponding Authors
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(8) John, J. M.; Bergens, S. H. Angew. Chem., Int. Ed. 2011, 50, 10377.
(9) Krackl, S.; Someya, C. I.; Enthaler, S. Chem.Eur. J. 2012, 18,
15267.
(10) For reviews of metal-mediated radical reactions, see: (a) Gansauer,
̈
Author Contributions
A.; Bluhm, H. Chem. Rev. 2000, 100, 2771. (b) Szostak, M.; Procter, D. J.
Angew. Chem., Int. Ed. 2012, 51, 9238. (c) Streuff, J. Synthesis 2013, 45,
†M. Spain and A. J. Eberhart contributed equally.
281. (d) Radicals in Synthesis I and II; Gansauer, A., Ed.; Topics in
̈
Notes
Current Chemistry, Vols. 263−264; Springer: Berlin, 2006. For recent
reviews of SmI2, see: (e) Molander, G. A.; Harris, C. R. Chem. Rev. 1996,
96, 307. (f) Krief, A.; Laval, A. M. Chem. Rev. 1999, 99, 745. (g) Kagan,
H. B. Tetrahedron 2003, 59, 10351. (h) Nicolaou, K. C.; Ellery, S. P.;
Chen, J. S. Angew. Chem., Int. Ed. 2009, 48, 7140. (i) Szostak, M.; Spain,
M.; Procter, D. J. Chem. Soc. Rev. 2013, 42, 9155.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
We acknowledge the EPSRC and GSK for financial support.
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(11) For selected studies of cyclizations of acyl-type radicals, see:
(a) Parmar, D.; Duffy, L. A.; Sadasivam, D. V.; Matsubara, H.; Bradley, P.
A.; Flowers, R. A., II; Procter, D. J. J. Am. Chem. Soc. 2009, 131, 15467.
(b) Parmar, D.; Matsubara, H.; Price, K.; Spain, M.; Procter, D. J. J. Am.
Chem. Soc. 2012, 134, 12751. (c) Sautier, B.; Lyons, S. E.; Webb, M. R.;
Procter, D. J. Org. Lett. 2012, 14, 146. (d) Szostak, M.; Sautier, B.; Spain,
M.; Behlendorf, M.; Procter, D. J. Angew. Chem., Int. Ed. 2013, 52, 12559.
(12) A study of the mechanism of ester reduction using SmI2/amine/
H2O will be reported separately.
(13) (a) Szostak, M.; Spain, M.; Procter, D. J. Chem. Commun. 2011,
47, 10254. (b) Szostak, M.; Spain, M.; Procter, D. J. Org. Lett. 2012, 14,
840. For other studies of SmI2/amine/H2O, see: (c) Cabri, W.;
Candiani, I.; Colombo, M.; Franzoi, L.; Bedeschi, A. Tetrahedron Lett.
REFERENCES
■
(1) (a) Hudlicky, M. Reductions in Organic Chemistry; Ellis Horwood
Ltd.: Chichester, U.K., 1984. (b) Seyden-Penne, J. Reductions by the
Alumino- and Borohydrides in Organic Synthesis; Wiley: New York, 1997.
(c) Modern Reduction Methods; Andersson, P. G., Munslow, I. J., Eds.;
Wiley-VCH: Weinheim, Germany, 2008. (d) Addis, D.; Das, S.; Junge,
K.; Beller, M. Angew. Chem., Int. Ed. 2011, 50, 6004.
(2) (a) Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.;
Pergamon Press: Oxford, U.K., 1991. (b) Modern Amination Methods;
Ricci, A., Ed.; Wiley-VCH: Weinheim, Germany, 2000. (c) Carey, J. S.;
Laffan, D.; Thomson, C.; Williams, M. T. Org. Biomol. Chem. 2006, 4,
2337.
(3) For selected recent examples, see: (a) Das, S.; Addis, D.; Zhou, S.;
Junge, K.; Beller, M. J. Am. Chem. Soc. 2010, 132, 1770. (b) Das, S.;
1995, 36, 949. (d) Dahlen
1123. (e) Dahlen, A.; Hilmersson, G. J. Am. Chem. Soc. 2005, 127, 8340.
(f) Ankner, T.; Hilmersson, G. Tetrahedron 2009, 65, 10856. (g) Ankner,
́
, A.; Hilmersson, G. Chem.Eur. J. 2003, 9,
́
Wendt, B.; Moller, K.; Junge, K.; Beller, M. Angew. Chem., Int. Ed. 2012,
̈
51, 1662. (c) Das, S.; Join, B.; Junge, K.; Beller, M. Chem. Commun.
2012, 48, 2683. (d) Das, S.; Addis, D.; Junge, K.; Beller, M. Chem.Eur.
J. 2011, 17, 12186. (e) Zhou, S.; Junge, K.; Addis, D.; Das, S.; Beller, M.
Angew. Chem., Int. Ed. 2009, 48, 9507. For an excellent review, see:
(f) Das, S.; Zhou, S.; Addis, D.; Junge, K.; Enthaler, S.; Beller, M. Top.
Catal. 2010, 53, 979. (g) Barbe, G.; Charette, A. B. J. Am. Chem. Soc.
2008, 130, 18. (h) Pelletier, G.; Bechara, W. S.; Charette, A. B. J. Am.
Chem. Soc. 2010, 132, 12817. For an elegant application of
chemoselective amide bond activation, see: (i) Bechara, W. S.;
Pelletier, G.; Charette, A. B. Nat. Chem. 2012, 4, 228. (j) Reeves, J.
T.; Tan, Z.; Marsini, M. A.; Han, Z. S.; Xu, Y.; Reeves, D. C.; Lee, H.; Lu,
B. Z.; Senanayake, C. H. Adv. Synth. Catal. 2013, 355, 47. (k) Stein, M.;
Breit, B. Angew. Chem., Int. Ed. 2013, 52, 2231. (l) Cheng, C.; Brookhart,
M. J. Am. Chem. Soc. 2012, 134, 11304. (m) Park, S.; Brookhart, M. J.
Am. Chem. Soc. 2012, 134, 640. (n) Hanada, S.; Tsutsumi, E.;
Motoyama, Y.; Nagashima, H. J. Am. Chem. Soc. 2009, 131, 15032.
(o) Motoyama, Y.; Mitsui, K.; Ishida, T.; Nagashima, H. J. Am. Chem.
Soc. 2005, 127, 13150. (p) Sunada, Y.; Kawakami, H.; Imaoka, T.;
Motoyama, Y.; Nagashima, H. Angew. Chem., Int. Ed. 2009, 48, 9511.
(q) White, J. M.; Tunoori, A. R.; Georg, G. I. J. Am. Chem. Soc. 2000, 122,
11995. (r) Spletstoser, J. T.; White, J. M.; Tunoori, A. R.; Georg, G. I. J.
Am. Chem. Soc. 2007, 129, 3408.
T.; Stalsmeden, A. S.; Hilmersson, G. Chem. Commun. 2013, 49, 6867.
̊
(14) Kamochi and Kudo described the reduction of aryl carboxylic acid
derivatives using SmI2, but this process is low-yielding and/or limited in
scope. See: (a) Kamochi, Y.; Kudo, T. Chem. Lett. 1993, 1495.
(b) Kamochi, Y.; Kudo, T. Bull. Chem. Soc. Jpn. 1992, 65, 3049.
Electrochemical methods for the reduction of amides have been
reported. See: (c) Benkeser, R. A.; Watanabe, H.; Mels, S. J.; Sabol, M. A.
J. Org. Chem. 1970, 35, 1210. (d) Shono, T.; Masuda, H.; Murase, H.;
Shimomura, M.; Kashimura, S. J. Org. Chem. 1992, 57, 1061.
(15) Cyclic carboxylic acid derivatives are more reactive towards
Sm(II) because of anomeric stabilization of the radical anion.11a
(16) Szostak, M.; Spain, M.; Choquette, K. A.; Flowers, R. A., II;
Procter, D. J. J. Am. Chem. Soc. 2013, 135, 15702.
(17) Complete recovery of the staring material was observed. In
contrast, lithium amidotrihydroborate affords mixtures of C−N/C−O
cleavage products with similar substrates.5d This divergent reactivity
should prove useful in the selective reduction of this class of amides.
(18) Newcomb, M. Tetrahedron 1993, 49, 1151.
́
(19) (a) Dahlen, A.; Hilmersson, G. Eur. J. Inorg. Chem. 2004, 3393.
(b) Flowers, R. A., II. Synlett 2008, 1427. (c) Szostak, M.; Spain, M.;
Parmar, D.; Procter, D. J. Chem. Commun. 2012, 48, 330.
(20) (a) Tsuruta, H.; Yamaguchi, K.; Imamoto, T. Chem. Commun.
1999, 1703. (b) Evans, W. J. Inorg. Chem. 2007, 46, 3435.
(21) (a) Laurence, C.; Gal, J.-F. Lewis Basicity and Affinity Scales: Data
and Measurement; Wiley-Blackwell: Chichester, U.K., 2009. (b) Cox, C.;
Lectka, T. Acc. Chem. Res. 2000, 33, 849.
(4) Brown, H. C.; Kim, S. C. Synthesis 1977, 635.
(5) (a) Hutchins, R. O.; Learn, K.; El-Telbany, F.; Stercho, Y. P. J. Org.
Chem. 1984, 49, 2438. (b) Fisher, G. B.; Fuller, J. C.; Harrison, J.;
Alvarez, S. G.; Burkhardt, E. R.; Goralski, C. T.; Singaram, B. J. Org.
Chem. 1994, 59, 6378. For an excellent overview, see: (c) Pasumansky,
L.; Goralski, C. T.; Singaram, B. Org. Process Res. Dev. 2006, 10, 959.
(d) Myers, A. G.; Yang, B. H.; Kopecky, D. J. Tetrahedron Lett. 1996, 37,
3623. (e) Myers, A. G.; Yang, B. H.; Chen, H.; McKinstry, L.; Kopecky,
D. J.; Gleason, J. L. J. Am. Chem. Soc. 1997, 119, 6496.
(6) (a) Balaraman, E.; Gnanaprakasam, B.; Shimon, L. J. W.; Milstein,
D. J. Am. Chem. Soc. 2010, 132, 16756. For other elegant applications of
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