The Synthesis of Hydrobenzoin-Based Monoaza Crown Ethers and Their Application as Recyclable Enantioselective Catalysts

Tamás Nemcsok, Zsolt Rapi, Péter Bagi, Attila Oláh, György Keglevich, Péter Bakó

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Abstract

Abstract: New recyclable monoaza-15-crown ethers have been synthesized starting from (R,R)-(+)- and (S,S)-(−)-hydrobenzoin. These macrocycles proved to be efficient and reusable phase transfer catalysts in a few asymmetric reactions under mild conditions. The asymmetric epoxidation of trans-chalcone took place with up to 81% ee, while using other chalcone derivatives, the products were formed with 68–88% ee. The hydrobenzoin-based lariat ethers were also tested in the cyclopropanation of a few electron deficient olefins using diethyl bromomalonate to afford the product with good enantioselectivities (54–75% ee). The catalysts were recovered by salt formation, followed by extraction, and were reused without the loss of the activity and effect on the enantioselectivity. Graphic Abstract: The synthesis of hydrobenzoin-based monaza crown ethers and their application as recyclable enantioselective catalysts.[Figure not available: see fulltext.].

Original languageEnglish
Pages (from-to)930-938
Number of pages9
JournalCatalysis Letters
Volume150
Issue number4
DOIs
Publication statusPublished - Apr 1 2020

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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