Organic Letters
Letter
(f) Spasyuk, D.; Smith, S.; Gusev, D. G. Angew. Chem., Int. Ed. 2013,
52, 2538. (g) Chakraborty, S.; Dai, H.; Bhattacharya, P.; Fairweather,
N. T.; Gibson, M. S.; Krause, J. A.; Guan, H. J. Am. Chem. Soc. 2014,
136, 7869. (h) Filonenko, G. A.; Cosimi, E.; Lefort, L.; Conley, M. P.;
5 and 6). The hydrogenation of more sterically congested ethyl
and tert-butyl esters also furnished benzyl alcohol as the alcohol
as well (entries 7 and 8). The substrates need not be aromatic
for the hydrogenation to be successfulmethyl heptanoate was
completely reduced to 1-heptanol in 94% yield (entry 9). In the
case of γ-butyrolactone, although hydrolysis proceeded
competitively, the desired 1,4-diol was obtained in 73% yield
(entry 10).
In summary, the incorporation of NHC ligands into the
bifunctional PNP−ruthenium complex results in an outstanding
ester hydrogenation catalyst, compared to the catalyst systems
based on the well-defined Ru-pincer complexes that have
emerged to date. The atmospheric hydrogenation of esters was
achieved by the isolable NHC-coordinated PNP−ruthenium
complex in THF at a nonsevere temperature of 50 °C. The
hydrogenation can be conducted using glassware reactors such
as a Schlenk flask equipped with a balloon containing H2 and
thus provides a practical protocol for reduction of esters.
Further studies are in progress to evaluate the utility of this
catalyst in other challenging hydrogenations.
́
Coperet, C.; Lutz, M.; Hensen, E. J. M.; Pidko, E. A. ACS Catal. 2014,
4, 2667. (i) Li, W.; Xie, J.-H.; Yuan, M.-L.; Zhou, Q.-L. Green Chem.
2014, 16, 4081. (j) Tan, X.; Wang, Y.; Liu, Y.; Wang, F.; Shi, L.; Lee,
K.-H.; Lin, Z.; Lv, H.; Zhang, X. Org. Lett. 2015, 17, 454. (k) Dub, P.
A.; Scott, B. L.; Gordon, J. C. Organometallics 2015, 34, 4464.
(l) Werkmeister, S.; Neumann, J.; Junge, K.; Beller, M. Chem. - Eur. J.
2015, 21, 12226. (m) Srimani, D.; Mukherjee, A.; Goldberg, A. F. G.;
Leitus, G.; Diskin-Posner, Y.; Shimon, L. J. W.; David, Y. B.; Milstein,
D. Angew. Chem., Int. Ed. 2015, 54, 12357. (n) Filonenko, G. A.;
Aguila, M. J. B.; Schulpen, E. N.; van Putten, R.; Wiecko, J.; Muller, C.;
̈
Lefort, L.; Hensen, E. J. M.; Pidko, E. A. J. Am. Chem. Soc. 2015, 137,
7620. (o) Kim, D.; Le, L.; Drance, M. J.; Jensen, K. H.; Bogdanovski,
K.; Cervarich, T. N.; Barnard, M. G.; Pudalov, N. J.; Knapp, S. M. M.;
Chianese, A. R. Organometallics 2016, 35, 982. (p) Elangovan, S.;
Wendt, B.; Topf, C.; Bachmann, S.; Scalone, M.; Spannenberg, A.;
Jiao, H.; Baumann, W.; Junge, K.; Beller, M. Adv. Synth. Catal. 2016,
358, 820.
(6) Recent reports on the Ru-catalyzed transfer hydrogenation of
esters using alcohols as hydrogen donors: (a) Dubey, A.; Khaskin, E.
ACS Catal. 2016, 6, 3998−4002. (b) Lee, S.-H.; Nikonov, G. I.
ChemCatChem 2015, 7, 107−113.
(7) (a) Herrmann, W. A. Angew. Chem., Int. Ed. 2002, 41, 1290.
(b) Dorta, R.; Stevens, E. D.; Hoff, C. D.; Nolan, S. P. J. Am. Chem.
Soc. 2003, 125, 10490. (c) Dorta, R.; Stevens, E. D.; Scott, N. M.;
Costabile, C.; Cavallo, L.; Hoff, C. D.; Nolan, S. P. J. Am. Chem. Soc.
2005, 127, 2485. (d) Gusev, D. G. Organometallics 2009, 28, 6458.
ASSOCIATED CONTENT
* Supporting Information
■
S
The Supporting Information is available free of charge on the
Experimental section, characterization data, X-ray data
Crystallographic data for 7 (CIF)
(e) del Pozo, C.; Iglesias, M.; San
2180. (f) Fernandez, F. E.; Puerta, M. C.; Valerga, P. Organometallics
2012, 31, 6868.
́
chez, F. l. Organometallics 2011, 30,
́
(8) Friedrich, A.; Drees, M.; Kass, M.; Herdtweck, E.; Schneider, S.
Inorg. Chem. 2010, 49, 5482.
̈
AUTHOR INFORMATION
■
(9) (a) Lin, I. J. B.; Vasam, C. S. Coord. Chem. Rev. 2007, 251, 642.
(b) Wang, H. M. J.; Lin, I. J. B. Organometallics 1998, 17, 972.
(10) Holbrey, J. D.; Reichert, W. M.; Tkatchenko, I.; Bouajila, E.;
Walter, O.; Tommasi, I.; Rogers, R. D. Chem. Commun. 2003, 28.
(11) Roberts, G. M.; Pierce, P. J.; Woo, L. K. Organometallics 2013,
32, 2033.
(12) (a) Zhang, Y.; Chen, C.; Ghosh, S. C.; Li, Y.; Hong, S. H.
Organometallics 2010, 29, 1374. (b) Voutchkova, A. M.; Appelhans, L.
N.; Chianese, A. R.; Crabtree, R. H. J. Am. Chem. Soc. 2005, 127,
17624.
Corresponding Authors
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This study was financially supported by JSPS KAKENHI Grant
Numbers 24350079 and 26621043. The authors thank our
analytical technology research team for 13C NMR and mass
spectroscopic data.
(13) The results of the hydrogenation conducted at 0.4 MPa of
REFERENCES
■
(1) Seyden-Penne, J. Reductions by the Alumino- and Borohydrides in
Organic Synthesis; VCH Publishers: New York, 1997.
(2) Rieke, R. D.; Thakur, D. S.; Roberts, B. D.; White, G. T. J. Am.
Oil Chem. Soc. 1997, 74, 333.
(3) Zhang, J.; Leitus, G.; Ben-David, Y.; Milstein, D. Angew. Chem.,
Int. Ed. 2006, 45, 1113.
(4) (a) Dub, P.; Ikariya, T. ACS Catal. 2012, 2, 1718.
(b) Werkmeister, S.; Junge, K.; Beller, M. Org. Process Res. Dev.
2014, 18, 289. (c) Saudan, L. A.; Saudan, C. M.; Debieux, C.; Wyss, P.
Angew. Chem., Int. Ed. 2007, 46, 7473. (d) Khusnutdinova, J. R.;
Milstein, D. Angew. Chem., Int. Ed. 2015, 54, 12236.
(5) (a) Kuriyama, W.; Matsumoto, T.; Ogata, O.; Ino, Y.; Aoki, K.;
Tanaka, S.; Ishida, K.; Kobayashi, T.; Sayo, N.; Saito, T. Org. Process
Res. Dev. 2012, 16, 166. (b) Clarke, M. L.; Diaz-Valenzuela, M. B.;
Slawin, A. M. Z. Organometallics 2007, 26, 16. (c) Fogler, E.;
Balaraman, E.; Ben-David, Y.; Leitus, G.; Shimon, L. J. W.; Milstein, D.
Organometallics 2011, 30, 3826. (d) Sun, Y.; Koehler, C.; Tan, R.;
Annibale, V. T.; Song, D. Chem. Commun. 2011, 47, 8349. (e) Spasyuk,
D.; Smith, S.; Gusev, D. G. Angew. Chem., Int. Ed. 2012, 51, 2772.
D
Org. Lett. XXXX, XXX, XXX−XXX