Membrane-Grafted Asymmetric Organocatalyst for an Integrated Synthesis-Separation Platform

Christos Didaskalou; Jozsef Kupai; Levente Cseri; Julia Barabas; Elemer Vass; Tibor Holtzl; Gyorgy Szekely

doi:10.1021/acscatal.8b01706

Membrane-Grafted Asymmetric Organocatalyst for an Integrated Synthesis-Separation Platform

Christos Didaskalou, Jozsef Kupai, Levente Cseri, Julia Barabas, Elemer Vass, Tibor Holtzl, Gyorgy Szekely^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

89 Scopus citations

Abstract

In this work we introduce a sustainable membrane-based synthesis-separation platform for enantioselective organocatalysis. An azido derivatized cinchona-squaramide bifunctional catalyst was synthesized and subsequently grafted to the surface of a polybenzimidazole-based nanofiltration membrane. The favorable effect of the covalent grafting - due to the change in geometry and increased secondary interactions - on the catalytic activity due to conformational changes was confirmed by quantum chemical calculations. Asymmetric Michael and aza-Michael reactions of 1,3-dicarbonyl and indole, pyrazole, and triazole derivatives to β-nitrostyrene were performed with as high as 99% enantiomeric excess. This report on the enantioselective aza-Michael reaction of pyrazoles and triazoles opens new frontiers in the application of squaramide-based cinchona catalysts. A catalytic membrane cascade reactor was developed for an integrated synthesis-purification process allowing at least 98% product and substrate recovery, and quantitative in situ solvent recycling. The sustainability of the synthetic methodology was assessed through E-factor and carbon footprint.

Original language	English (US)
Pages (from-to)	7430-7438
Number of pages	9
Journal	ACS Catalysis
Volume	8
Issue number	8
DOIs	https://doi.org/10.1021/acscatal.8b01706
State	Published - Aug 3 2018
Externally published	Yes

Bibliographical note

Funding Information:
The authors would like to express their gratitude to Mr. Gareth David Smith and the MS laboratory (The University of Manchester) for the MS measurements. The authors are grateful to Mr. Fan Fei (The University of Manchester) for the technical assistance with the AFM-IR. The authors wish to thank the Reviewers for their valuable and insightful comments shaping the final version of this article. J.K. is grateful for the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences. This work was supported by the Biotechnology and Biological Sciences Research Council [BB/L013770/1] and the Central Hungarian Operational Programme (KMOP-4.2.1/B-10-2011-0002).

Publisher Copyright:
Copyright © 2018 American Chemical Society.

Keywords

Michael addition
catalytic membrane reactor
cinchona-squaramide
enantioselective catalysis
organic solvent nanofiltration
polybenzimidazole
recycling
surface modification

ASJC Scopus subject areas

Catalysis
Chemistry(all)

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10.1021/acscatal.8b01706

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title = "Membrane-Grafted Asymmetric Organocatalyst for an Integrated Synthesis-Separation Platform",

abstract = "In this work we introduce a sustainable membrane-based synthesis-separation platform for enantioselective organocatalysis. An azido derivatized cinchona-squaramide bifunctional catalyst was synthesized and subsequently grafted to the surface of a polybenzimidazole-based nanofiltration membrane. The favorable effect of the covalent grafting - due to the change in geometry and increased secondary interactions - on the catalytic activity due to conformational changes was confirmed by quantum chemical calculations. Asymmetric Michael and aza-Michael reactions of 1,3-dicarbonyl and indole, pyrazole, and triazole derivatives to β-nitrostyrene were performed with as high as 99% enantiomeric excess. This report on the enantioselective aza-Michael reaction of pyrazoles and triazoles opens new frontiers in the application of squaramide-based cinchona catalysts. A catalytic membrane cascade reactor was developed for an integrated synthesis-purification process allowing at least 98% product and substrate recovery, and quantitative in situ solvent recycling. The sustainability of the synthetic methodology was assessed through E-factor and carbon footprint.",

keywords = "Michael addition, catalytic membrane reactor, cinchona-squaramide, enantioselective catalysis, organic solvent nanofiltration, polybenzimidazole, recycling, surface modification",

author = "Christos Didaskalou and Jozsef Kupai and Levente Cseri and Julia Barabas and Elemer Vass and Tibor Holtzl and Gyorgy Szekely",

note = "Funding Information: The authors would like to express their gratitude to Mr. Gareth David Smith and the MS laboratory (The University of Manchester) for the MS measurements. The authors are grateful to Mr. Fan Fei (The University of Manchester) for the technical assistance with the AFM-IR. The authors wish to thank the Reviewers for their valuable and insightful comments shaping the final version of this article. J.K. is grateful for the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences. This work was supported by the Biotechnology and Biological Sciences Research Council [BB/L013770/1] and the Central Hungarian Operational Programme (KMOP-4.2.1/B-10-2011-0002). Publisher Copyright: Copyright {\textcopyright} 2018 American Chemical Society.",

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doi = "10.1021/acscatal.8b01706",

language = "English (US)",

volume = "8",

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AU - Didaskalou, Christos

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AU - Cseri, Levente

AU - Barabas, Julia

AU - Vass, Elemer

AU - Holtzl, Tibor

AU - Szekely, Gyorgy

N1 - Funding Information: The authors would like to express their gratitude to Mr. Gareth David Smith and the MS laboratory (The University of Manchester) for the MS measurements. The authors are grateful to Mr. Fan Fei (The University of Manchester) for the technical assistance with the AFM-IR. The authors wish to thank the Reviewers for their valuable and insightful comments shaping the final version of this article. J.K. is grateful for the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences. This work was supported by the Biotechnology and Biological Sciences Research Council [BB/L013770/1] and the Central Hungarian Operational Programme (KMOP-4.2.1/B-10-2011-0002). Publisher Copyright: Copyright © 2018 American Chemical Society.

PY - 2018/8/3

Y1 - 2018/8/3

N2 - In this work we introduce a sustainable membrane-based synthesis-separation platform for enantioselective organocatalysis. An azido derivatized cinchona-squaramide bifunctional catalyst was synthesized and subsequently grafted to the surface of a polybenzimidazole-based nanofiltration membrane. The favorable effect of the covalent grafting - due to the change in geometry and increased secondary interactions - on the catalytic activity due to conformational changes was confirmed by quantum chemical calculations. Asymmetric Michael and aza-Michael reactions of 1,3-dicarbonyl and indole, pyrazole, and triazole derivatives to β-nitrostyrene were performed with as high as 99% enantiomeric excess. This report on the enantioselective aza-Michael reaction of pyrazoles and triazoles opens new frontiers in the application of squaramide-based cinchona catalysts. A catalytic membrane cascade reactor was developed for an integrated synthesis-purification process allowing at least 98% product and substrate recovery, and quantitative in situ solvent recycling. The sustainability of the synthetic methodology was assessed through E-factor and carbon footprint.

AB - In this work we introduce a sustainable membrane-based synthesis-separation platform for enantioselective organocatalysis. An azido derivatized cinchona-squaramide bifunctional catalyst was synthesized and subsequently grafted to the surface of a polybenzimidazole-based nanofiltration membrane. The favorable effect of the covalent grafting - due to the change in geometry and increased secondary interactions - on the catalytic activity due to conformational changes was confirmed by quantum chemical calculations. Asymmetric Michael and aza-Michael reactions of 1,3-dicarbonyl and indole, pyrazole, and triazole derivatives to β-nitrostyrene were performed with as high as 99% enantiomeric excess. This report on the enantioselective aza-Michael reaction of pyrazoles and triazoles opens new frontiers in the application of squaramide-based cinchona catalysts. A catalytic membrane cascade reactor was developed for an integrated synthesis-purification process allowing at least 98% product and substrate recovery, and quantitative in situ solvent recycling. The sustainability of the synthetic methodology was assessed through E-factor and carbon footprint.

KW - Michael addition

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KW - recycling

KW - surface modification

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JF - ACS Catalysis

IS - 8

ER -

Membrane-Grafted Asymmetric Organocatalyst for an Integrated Synthesis-Separation Platform

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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