Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• reactive in chloroform solution, while in methanol the corresponding phosphonium phenolate is formed. Keywords: Lewis-base catalysis; Michael acceptor reactivity; phospha-Michael reaction; phosphonium phenolate zwitterion; Introduction Organocatalysis has emerged in recent years as a valuable and

1,5-Phosphonium betaines from N-triflylpropiolamides, triphenylphosphane, and active methylene compounds

• Vito A. Fiore,
• Chiara Freisler and
• Gerhard Maas

Beilstein J. Org. Chem. 2019, 15, 2603–2611, doi:10.3762/bjoc.15.253

• -Michael reaction; propiolamides; Introduction Beside the well-known phosphonium ylides (Wittig ylides, methylenephosphoranes), various other types of zwitterions containing a tetravalent phosphonium moiety (phosphonium betaines) exist. They are often considered as reaction intermediates, but reports on

• fractionating crystallization. Structure determination by X-ray diffraction analysis revealed marked conformational differences around the CH–C(O–) single bond of E and Z-isomers and extended charge delocalization in the anionic part. Keywords: betaines; multi-component reactions; N-triflylamides; phospha