New enantiopure binaphthyl-cinchona thiosquaramides: synthesis and application for enantioselective organocatalysis

Sándor Nagy, Gyula Dargó, Péter Kisszékelyi, Zsuzsanna Fehér, András Simon, Júlia Barabás, Tibor Höltzl, Béla Mátravölgyi, Levente Kárpáti, L. Drahos, P. Huszthy, József Kupai

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

This work presents the first successful applications of cinchona-thiosquaramides in asymmetric reactions. Binaphthyl-cinchona squaramides and thiosquaramides were synthesised, and then used as organocatalysts to promote the catalytic enantioselective Michael addition reaction of pentane-2,4-dione to trans-β-nitrostyrene with excellent yields (up to 99%) and enantioselectivities (up to 99% ee) at as low as 0.2 mol% catalyst loadings. Thiosquaramides gave higher enantioselectivities (up to 92% ee) in conjugate addition reaction of lawsone to β,γ-unsaturated α-keto ester than its oxo analogue, with high yields (up to 100%). Also, only thiosquaramide could catalyse the aza-Diels-Alder addition reaction of 2-siloxydiene to benzylideneacetone. Furthermore, quantum chemical computations showed that the geometrical structure of binaphthyl-cinchona thiosquaramide is similar to that of squaramide.

Original languageEnglish
Pages (from-to)5948-5959
Number of pages12
JournalNew Journal of Chemistry
Volume43
Issue number15
DOIs
Publication statusPublished - Jan 1 2019

    Fingerprint

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Materials Chemistry

Cite this

Nagy, S., Dargó, G., Kisszékelyi, P., Fehér, Z., Simon, A., Barabás, J., Höltzl, T., Mátravölgyi, B., Kárpáti, L., Drahos, L., Huszthy, P., & Kupai, J. (2019). New enantiopure binaphthyl-cinchona thiosquaramides: synthesis and application for enantioselective organocatalysis. New Journal of Chemistry, 43(15), 5948-5959. https://doi.org/10.1039/C8NJ06451B