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
. 2018 Nov 22;9(1):4936.
doi: 10.1038/s41467-018-07351-2.

Visible light-promoted CO2 fixation with imines to synthesize diaryl α-amino acids

Xinyuan Fan  1 , Xu Gong  2 , Mengyue Ma  2 , Rui Wang  2 , Patrick J Walsh  3   4
Affiliations

Visible light-promoted CO2 fixation with imines to synthesize diaryl α-amino acids

Xinyuan Fan et al. Nat Commun. .

Abstract

Light-mediated transformations with CO2 have recently attracted great attention, with the focus on CO2 incorporation into C-C double and triple bonds, organohalides and amines. Herein is demonstrated visible light -mediated umpolung imine reactivity capable of engaging CO2 to afford α-amino acid derivatives. By employing benzophenone ketimine derivatives, CO2 fixation by hydrocarboxylation of C=N double bonds is achieved. Good to excellent yields of a broad range of α,α-disubstituted α-amino acid derivatives are obtained under mild conditions (rt, atmospheric pressure of CO2, visible light). A procedure that avoids tedious chromatographic purification and uses sustainable sunlight is developed to highlight the simplicity of this method.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Fixation of CO2 under photoredox catalysis. a Reaction of CO2 with olefins and alkynes. b Reactions of C–X bonds with CO2. c C–H functionalization of amines with CO2. d Past work by our group and Polyzos. e Unpolung hydrocarboxylation of C=N bonds with CO2 (this work)
Fig. 2
Fig. 2
Visible light-mediated catalytic hydrocarboxylation of ketimines using CO2. Reactions were conducted with 1 (0.2 mmol), CO2 (balloon), Ir-7 (0.5 mol%), and Cy2NMe (0.4 mmol) in 2 mL MeCN at RT under 20 W blue LED irradiation. 2 mol% of Ir-7 was used in the case of 3x. Isolated yields
Fig. 3
Fig. 3
Chromatography-free syntheses. Preparation of α-amino acids using CO2 and ketimines without chromatographic purification
Fig. 4
Fig. 4
Upscaling experiments. Gram-scale preparation of α-amino acids via fixation of CO2 promoted by visible light or sunlight
Fig. 5
Fig. 5
Further synthetic applications. Synthesis of enantioenriched iminodiacetic acid derivatives from α-amino acid derivatives
Fig. 6
Fig. 6
Applications of α,α-diaryl α-amino acids. a Potential targets and b deprotection of amino acid derivative 4aa on 2 gram scale
Fig. 7
Fig. 7
Reaction pathway. a Plausible mechanism. b Computational spin density of the radical anion intermediate
See this image and copyright information in PMC

References

    1. Aresta, M. & Dibenedetto, A. Utilisation of CO2 as a chemical feedstock: opportunities and challenges. Dalton Trans. 2975–2992 (2007). - PubMed
    1. Sakakura T, Choi JC, Yasuda H. Transformation of carbon dioxide. Chem. Rev. 2007;107:2365–2387. doi: 10.1021/cr068357u. - DOI - PubMed
    1. Cokoja M, Bruckmeier C, Rieger B, Herrmann WA, Kühn FE. Transformation of carbon dioxide with homogeneous transition-metal catalysts: a molecular solution to a global challenge? Angew. Chem. Int. Ed. 2011;50:8510–8537. doi: 10.1002/anie.201102010. - DOI - PubMed
    1. Aresta M, Dibenedetto A, Angelini A. Catalysis for the valorization of exhaust carbon: from CO2 to chemicals, materials, and fuels. technological use of CO2. Chem. Rev. 2014;114:1709–1742. doi: 10.1021/cr4002758. - DOI - PubMed
    1. Fiorani G, Guo W, Kleij AW. Sustainable conversion of carbon dioxide: the advent of organocatalysis. Green Chem. 2015;17:1375–1389. doi: 10.1039/C4GC01959H. - DOI

Publication types