Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2012:3:887-891.
doi: 10.1039/C1SC00724F. Epub 2011 Oct 31.

Direct Aerobic α, β-Dehydrogenation of Aldehydes and Ketones with a Pd(TFA)(2)/4,5-Diazafluorenone Catalyst()

Tianning Diao  1 , Tyler J Wadzinski, Shannon S Stahl
Affiliations

Direct Aerobic α, β-Dehydrogenation of Aldehydes and Ketones with a Pd(TFA)(2)/4,5-Diazafluorenone Catalyst()

Tianning Diao et al. Chem Sci. 2012.

Abstract

The direct α, β-dehydrogenation of aldehydes and ketones represents an efficient alternative to stepwise methods to prepare enal and enone products. Here, we describe a new Pd(TFA)(2)/4,5-diazafluorenone dehydrogenation catalyst that overcomes key limitations of previous catalyst systems. The scope includes successful reactivity with pharmaceutically important cyclopentanone and flavanone substrates, as well as acyclic ketones. Preliminary mechanistic studies compare the reactivity of this catalyst to previously reported dehydrogenation catalysts and reveal that cleavage of the α-C-H bond of the ketone is the turnover-limiting step of the catalytic mechanism.

PubMed Disclaimer

Figures

Scheme 1
Scheme 1
Palladium-catalyzed dehydrogenation of cyclohexanones
Scheme 2
Scheme 2
Attempted dehydrogenation of a pharmaceutically important cyclopentanone derivative
Scheme 3
Scheme 3
Dehydrogenation of β-aryl carbonyl compounds
Scheme 4
Scheme 4
Aerobic dehydrogenation of naringenin with the Pd(TFA)2/diazafluorenone catalyst system.
Scheme 5
Scheme 5
Kinetic isotope effects based on independent initial-rate measurements
Scheme 6
Scheme 6
Proposed catalytic cycle for Pd-catalyzed α,β-dehydrogenation of carbonyl compounds
See this image and copyright information in PMC

References

    1. For reviews of methods for α,β-dehydrogenation of carbonyl compounds, see: Buckle DR, Pinto IL. In: Comprehensive Organic Synthesis. Trost BM, Fleming I, editors. Vol. 7. Oxford; 1991. p. 119.Larock RC. Comprehensive Organic Transformations. John Wiley & Sons; New York: 1999. p. 251.

    1. Miller B, Wong H. Tetrahedron. 1972;28:2369.
    2. Stotter PL, Hill KA. J Org Chem. 1973;38:2576.

    1. For a leading reference and review of selenium based reagents, see: Sharpless KB, Lauer RF, Teranishi AY. J Am Chem Soc. 1973;95:6137.Reich HJ. Acc Chem Res. 1979;12:22.

    1. Related sulfoxide elimination reactions are also used. For a leading reference, see: Trost BM, Salzmann TN, Hiroi K. J Am Chem Soc. 1976;98:4887.

    1. The original report and many subsequent applications of the Saegusa oxidation protocol use 0.5–1 equiv of PdII, but catalytic examples have also been reported. See the following leading references: Ito Y, Hirao T, Saegusa T. J Org Chem. 1978;43:1011.Larock RC, Hightower TR, Kraus GA, Hahn P, Zheng D. Tetrahedron Lett. 1995;36:2423.Yu JQ, Wu HC, Corey EJ. Org Lett. 2005;7:1415.