A m-quaterphenyl probe for absolute configurational assignments of primary and secondary amines

• Yuka Takeuchi,
• Mutsumi Kobayashi,
• Yuuka Gotoh,
• Mari Ikeda,
• Yoichi Habata,
• Tomohiko Shirai and
• Shunsuke Kuwahara

Beilstein J. Org. Chem. 2025, 21, 2211–2219, doi:10.3762/bjoc.21.168

• conformers, obtained via DFT calculations, show a correlation with both the sign and intensity of the experimentally observed CD spectra. Keywords: absolute configuration; chiral amine; chiral quaternary ammonium salt; circular dichroism; DFT calculation; Introduction Determining the absolute

Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines

• Michał Błauciak,
• Dominika Andrzejczyk,
• Błażej Dziuk and
• Rafał Kowalczyk

Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198

• reactivity by chiral quaternary ammonium salt in the asymmetric variant of the phase-transfer catalysis. Nevertheless, no product was formed despite several conditions being examined. Finally, an attempt to activate the electrophile was performed. We chose iminium salt catalysis particularly employing chiral

Towards an asymmetric β-selective addition of azlactones to allenoates

• Behzad Nasiri,
• Ghaffar Pasdar,
• Paul Zebrowski,
• Katharina Röser,
• David Naderer and
• Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1504–1509, doi:10.3762/bjoc.20.134

• , Iran 10.3762/bjoc.20.134 Abstract We herein report the asymmetric organocatalytic addition of azlactones to allenoates. Upon using chiral quaternary ammonium salt catalysts, i.e., Maruoka’s binaphthyl-based spirocyclic ammonium salts, the addition of various azlactones to allenoates proceeds in a β

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• sequence including protection/deprotection steps for the benzyl groups. The catalytic efficiency of calix[4]arene-based phase-transfer catalyst 7 was evaluated in the benchmark reaction (Scheme 3) and compared with that of the chiral quaternary ammonium salt 8. The results obtained when 7 used as

Enantioselective nucleophilic difluoromethylation of aromatic aldehydes with Me₃SiCF₂SO₂Ph and PhSO₂CF₂H reagents catalyzed by chiral quaternary ammonium salts

• Chuanfa Ni,
• Fang Wang and
• Jinbo Hu

Beilstein J. Org. Chem. 2008, 4, No. 21, doi:10.3762/bjoc.4.21

• imines has been realized with PhSO2CF2H and related reagents, there are still no reports on the enantioselective nucleophilic reactions. Results With a chiral quaternary ammonium salt as the catalyst and KOH as the base, we describe the first enantioselective difluoromethylation of aromatic aldehydes

• difluoromethylation reaction of aromatic aldehydes with Me3SiCF2SO2Ph or PhSO2CF2H in the presence of a cinchona alkaloid-based chiral quaternary ammonium salt. Results and Discussion Enantioselective nucleophilic difluoromethylation of aromatic aldehydes with Me3SiCF2SO2Ph We started our investigation with the

• the ability of known chiral ammonium salts to promote the enantioselective difluoromethylation of aldehydes with PhSO2CF2H. In a preliminary study, we examined the reaction with the chiral quaternary ammonium salt 6a (see Scheme 1) as the phase transfer catalyst at room temperature, with 30% NaOH as