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. 2020 Jul 28;25(15):3420.
doi: 10.3390/molecules25153420.

Chiral Amphiphilic Secondary Amine-Porphyrin Hybrids for Aqueous Organocatalysis

Aitor Arlegui  1 , Pol Torres  1 , Victor Cuesta  1 , Joaquim Crusats  1   2 , Albert Moyano  1
Affiliations

Chiral Amphiphilic Secondary Amine-Porphyrin Hybrids for Aqueous Organocatalysis

Aitor Arlegui et al. Molecules. .

Abstract

Two chiral proline-derived amphiphilic 5-substituted-10,15,20-tris(4-sulfonatophenyl)porphyrins were prepared, and their pH-dependent supramolecular behavior was studied. In neutral aqueous solutions, the free-base form of the hybrids is highly soluble, allowing enamine-based organocatalysis to take place, whereas under acidic conditions, the porphyrinic protonated core of the hybrid leads to the formation of self-assembled structures, so that the hybrids flocculate and their catalytic activity is fully suppressed. The low degree of chirality transfer observed for aqueous Michael and aldol reactions strongly suggests that these reactions take place under true "in water" organocatalytic conditions. The highly insoluble catalyst aggregates can easily be separated from the reaction products by centrifugation of the acidic reaction mixtures, and after neutralization and desalting, the sodium salts of the sulfonated amine-porphyrin hybrids, retaining their full catalytic activity, can be recovered in high yield.

Keywords: J-aggregates; Michael reaction; aldol reaction; aqueous organocatalysis; porphyrins; switchable catalysis.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Scheme 1
Scheme 1
pH-switchable aminocatalysts based on in situ aggregation/dissociation of amphiphilic porphyrins.
Scheme 2
Scheme 2
Attempted preparation of 5-(N-Boc-2-(S)-pyrrolidinyl)-10,15,20-triphenylporphyrin 3.
Scheme 3
Scheme 3
Preparation of the (S)-5-[(pyrrolidin-1-ium-2-yl)methyl]-10,15,20-tris(4-sulfonatophenyl)porphyrin disodium salt 8.
Scheme 4
Scheme 4
Synthesis of N-Boc-(S)-2-[(4-formylpiperidin-1-yl)methyl]pyrrolidine 11.
Scheme 5
Scheme 5
Preparation of (S)-5-[1-(pyrrolidin-1-ium-2-ylmethyl)piperidin-1-ium-4-yl]-10,15,20-tris(4-sulfonatophenyl)porphyrin sodium salt 13.
Scheme 6
Scheme 6
Aqueous aldol reaction of cyclohexanone 14 with 4-nitrobenzaldehyde 15.
Scheme 7
Scheme 7
Preparation of compound 17.
Scheme 8
Scheme 8
Aqueous aldol reaction between acetone 18 and 4-nitrobenzaldehyde 15.
Scheme 9
Scheme 9
Aqueous Michael addition of cyclohexanone 14 to 2-nitrostyrene 20.
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References

    1. Blanco V., Leigh D.A., Marcos V. Artificial switchable catalysts. Chem. Soc. Rev. 2015;44:5341–5370. doi: 10.1039/C5CS00096C. - DOI - PubMed
    1. Guler M.O., Stupp S.I. A Self-Assembled Nanofiber Catalyst for Ester Hydrolysis. J. Am. Chem. Soc. 2007;129:12082–12083. doi: 10.1021/ja075044n. - DOI - PubMed
    1. Rodríguez-Llansola F., Escuder B., Miravet J.F. Switchable Performance of an L-Proline-Derived Basic Catalyst Controlled by Supramolecular Gelation. J. Am. Chem. Soc. 2009;131:11478–11484. doi: 10.1021/ja902589f. - DOI - PubMed
    1. Zhang C., Xue X., Luo Q., Li Y., Yang K., Zhuang X., Jiang Y., Zhang J., Liu J., Zou G., et al. Self-Assembled Peptide Nanofibers Designed as Biological Enzymes for Catalyzing Ester Hydrolysis. ACS Nano. 2014;8:11715–11723. doi: 10.1021/nn5051344. - DOI - PubMed
    1. Huerta E., van Genabeek B., Lamers B.A.G., Koenigs M.M.E., Meijer E.W., Palmans A.R.A. Triggering Activity of Catalytic Rod-Like Supramolecular Polymers. Chem. Eur. J. 2015;21:3682–3690. doi: 10.1002/chem.201405410. - DOI - PubMed