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 journalArticlepeer-review

89 Scopus citations


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 languageEnglish (US)
Pages (from-to)7430-7438
Number of pages9
JournalACS Catalysis
Issue number8
StatePublished - Aug 3 2018
Externally publishedYes

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.


  • 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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