Tetsuaki Fujihara et al.
COMMUNICATIONS
In conclusion, we have developed the palladium-
catalyzed reduction of carboxylic acids to the corre-
sponding aldehydes in the presence of hydrosilanes as
reducing agent and pivalic anhydride. A simple mix-
1981, 46, 4439–4445; c) J. H. Babler, B. J. Invergo, Tet-
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[
[
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2 3
1
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as a catalyst realized the reduction of various aliphatic
and aromatic carboxylic acids to aldehydes with good
functional group compatibility.
2
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Experimental Section
Typical Procedure for the Palladium-Catalyzed
Reduction of 3-Phenylpropionic acid (1a) with
H SiMePh (Table 1, entry 1)
2
2
281; f) F. Sato, T. Jinbo, M. Sato, Synthesis 1981, 871–
8
71.
Acid 1a (75 mg, 0.50 mmol), Pd
ACHTUNGENTRNUNG( dba) (14 mg, 0.025 mmol)
2
[5] a) K. Miyamoto, Y. Motoyama, H. Nagashima, Chem.
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and P(p-Tol) (15 mg, 0.050 mmol) were added to a 10-mL
ACHTUNGTRENNUNG
3
Schlenk flask with a magnetic stir bar. The flask was evacu-
ated and backfilled with argon three times. Then, toluene
1
0516; c) D. Bezier, S. Park, M. Brookhart, Org. Lett.
(
1.0 mL) was added to the flask and the resultant solution
was stirred at room temperature for 2 min. Pivalic anhydride
120 mL, 0.60 mmol) was added and the mixture was further
2
013, 15, 496–499.
[
6] a) K. Nagayama, I. Shimizu, A. Yamamoto, Chem.
Lett. 1998, 1143–1144; b) K. Nagayama, I. Shimizu, A.
Yamamoto, Bull. Chem. Soc. Jpn. 2001, 74, 1803–1815.
(
stirred for 15 min. Then, H SiMePh (76 mL, 0.55 mmol) was
2
added to the flask and the reaction mixture was stirred at
[
7] Abbreviations: dba: dibenzylideneacetone, PPhCy : di-
2
608C for 20 h under an argon atmosphere. After cooling to
cyclohexylphenylphosphane,
P ACHTUNGTRENNUNG( p-Tol) : tri-para-tolyl-
3
room temperature, the reaction mixture was diluted with di-
ethyl ether (5.0 mL) and tetradecane (50 mL, 0.19 mmol) as
an internal standard was added. The yield of 3-phenylpropa-
nal (2a; 99%) was analyzed by gas chromatography. 2a was
isolated by silica gel column chromatography (hexane:
EtOAc=13:1) as a colorless oil; yield: 50 mg (75%).
phosphane, PCy : tricyclohexylphosphane, P
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(o-Tol) :
3
3
tri-ortho-tolylphosphane, P ACHTUNGETRNN(UNG Mes) : tris(2,4,6-trimethyl-
3
phenyl)phosphane.
[
[
8] a) L. J. Gooßen, B. A. Khan, T. Fett, M. Treu, Adv.
Synth. Catal. 2010, 352, 2166–2170; b) L. J. Gooßen, K.
Ghosh, Chem. Commun. 2002, 836–837.
9] T. Fujihara, C. Cong, J. Terao, Y. Tsuji, Synlett 2012, 23,
2
389–2392.
[
10] a) T. Iwai, T. Fujihara, J. Terao, Y. Tsuji, J. Am. Chem.
Soc. 2012, 134, 1268–1274; b) T. Iwai, T. Fujihara, J.
Terao, Y. Tsuji, J. Am. Chem. Soc. 2009, 131, 6668–
6669.
Acknowledgements
This work was supported by Grant-in-Aid for Scientific Re-
search on Innovative Areas (“Molecular activation directed
toward straightforward synthesis” and “Organic synthesis
based on reaction integration”) from MEXT, Japan.
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3
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Adv. Synth. Catal. 2013, 355, 3420 – 3424