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- Title
Synthesis and Catalytic Activity of Bifunctional Phase-Transfer Organocatalysts Based on Camphor.
- Authors
Ciber, Luka; Požgan, Franc; Brodnik, Helena; Štefane, Bogdan; Svete, Jurij; Waser, Mario; Grošelj, Uroš
- Abstract
Ten novel bifunctional quaternary ammonium salt phase-transfer organocatalysts were synthesized in four steps from (+)-camphor-derived 1,3-diamines. These quaternary ammonium salts contained either (thio)urea or squaramide hydrogen bond donor groups in combination with either trifluoroacetate or iodide as the counteranion. Their organocatalytic activity was evaluated in electrophilic heterofunctionalizations of β-keto esters and in the Michael addition of a glycine Schiff base with methyl acrylate. α-Fluorination and chlorination of β-keto esters proceeded with full conversion and low enantioselectivities (up to 29% ee). Similarly, the Michael addition of a glycine Schiff base with methyl acrylate proceeded with full conversion and up to 11% ee. The new catalysts have been fully characterized; the stereochemistry at the C-2 chiral center was unambiguously determined.
- Subjects
CATALYTIC activity; QUATERNARY ammonium salts; AMMONIUM salts; SCHIFF bases; CHIRAL centers; STEREOCHEMISTRY; NITROALKENES; DIAMINES
- Publication
Molecules, 2023, Vol 28, Issue 3, p1515
- ISSN
1420-3049
- Publication type
Article
- DOI
10.3390/molecules28031515