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
. 2016 Feb 1;7(2):984-988.
doi: 10.1039/c5sc03597j. Epub 2015 Oct 30.

Synergistic catalysis: cis-cyclopropanation of benzoxazoles

Marta Meazza  1 , Mark E Light  1 , Andrea Mazzanti  2 , Ramon Rios  1
Affiliations

Synergistic catalysis: cis-cyclopropanation of benzoxazoles

Marta Meazza et al. Chem Sci. .

Abstract

In the present paper we report our latest efforts in pushing the boundaries of synergistic catalysis. We propose the use of 3 different catalytic cycles working in concert for the formation of cis cyclopropane derivatives of benzoxazoles with excellent stereoselectivities. This is the proof of concept that synergistic catalysis could be successfully used in cascade reactions.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1. Proposed catalytic cycles.
Fig. 2
Fig. 2. Proposed mechanism.
Scheme 1
Scheme 1. Scope of the reaction with several enals (d.r. determined by 1H NMR of the crude mixture, ee determined by chiral HPLC analysis of the isolated product).
Fig. 3
Fig. 3. Proposed mechanism for epimerization of 4i.
Fig. 4
Fig. 4. X-ray structure of compound 4d′ (minor diastereomer). The displacement ellipsoids are drawn at the 50% probability level.
Fig. 5
Fig. 5. TDDFT simulation of the ECD spectra for the two diastereomers of 4d [(S)-catalyst] and 4d′ [(R)-catalyst]. Shown simulations were obtained with TD-DFT at the M06-2X/6-311++G(2d,p) level of theory.
Scheme 2
Scheme 2. Scope of the reaction with several azaarenes (d.r. determined by 1H NMR of the crude mixture, ee determined by chiral HPLC analysis of the isolated product).
See this image and copyright information in PMC

References

    1. ; for a pioneering examples in multicatalysis using Rh and Pd see:

    2. Ibrahem I., Cordova A. Angew. Chem., Int. Ed. 2006;45:1952. - PubMed
    3. Sawamura M., Sudoh M., Ito Y. J. Am. Chem. Soc. 1996;118:3309.
    4. Sammis G. M., Danjo H., Jacobsen E. N. J. Am. Chem. Soc. 2004;126:9928. - PubMed
    1. Zhao X., Liu D., Xie F., Liu Y., Zhang W. Org. Biomol. Chem. 2011;9:1871. - PubMed

    1. See for example:

    2. Ding Q., Wu J. Org. Lett. 2007;9:4959. - PubMed
    3. Allen A. E., MacMillan D. W. C. J. Am. Chem. Soc. 2010;132:4986. - PMC - PubMed
    4. Ikeda M., Miyake Y., Nishibayashi Y. Angew. Chem., Int. Ed. 2010;49:7289. - PubMed
    5. Yoshida A., Ikeda M., Hattori G., Miyake Y., Nishibayashi Y. Org. Lett. 2011;13:592. - PubMed
    6. Sibi M. P., Hasegawa M. J. Am. Chem. Soc. 2007;129:4124. - PMC - PubMed
    7. Allen A. E., MacMillan D. W. C. J. Am. Chem. Soc. 2011;133:4260. - PMC - PubMed
    8. Nicewicz D. A., MacMillan D. W. C. Science. 2008;322:77. - PMC - PubMed
    1. Ibrahem I., Breistein P., Cordova A. Angew. Chem., Int. Ed. 2011;50:12036–12041. - PubMed
    2. Ibrahem I., Ma G., Afewerki S., Cordova A. Angew. Chem., Int. Ed. 2013;52:878–882. - PubMed
    3. Ibrahem I., Santoro S., Himo F., Cordova A. Adv. Synth. Catal. 2011;353:245–252.
    1. Jiang G., List B. Angew. Chem., Int. Ed. 2011;50:9471. - PubMed
    2. Jiang G., Halder R., Fang Y., List B. Angew. Chem., Int. Ed. 2011;50:9752. - PubMed
    3. Mukherjee S., List B. J. Am. Chem. Soc. 2007;129:11336. - PubMed
    4. Liao S., List B. Angew. Chem., Int. Ed. 2010;49:628. - PubMed
    5. Jiang G., List B. Adv. Synth. Catal. 2011;353:1667.
    6. Jiang G., List B. Chem. Commun. 2011;47:10022. - PubMed

LinkOut - more resources