The hitherto unreported ability of the methylsulfinyl carbanion (dimsyl anion) to generate acyl anion equivalents is described. The dimsyl anion, in fact, efficiently catalyses chemoselective intermolecular cross- benzoin condensations of diaryl α-diketones (benzils) with various aromatic and aliphatic aldehydes to give the corresponding aryl-aryl and aryl-alkyl benzoin benzoates in an atom-economic fashion. The dimsyl anion acts as an environmentally friendly alternative to the toxic cyanide anion and it is obtained by in situ deprotonation of DMSO solvent with a catalytic amount of a strong base, being t- BuOK the optimal promoter. The assumption that the methylsulfinyl carbanion is the active catalyst in the title transformation is supported by electrospray ionization mass spectrometry (ESI-MS) experiments.

Methylsulfinyl (Dimsyl) Anion as Umpolung Catalyst for the Chemoselective Cross Benzoin Reaction of α-Diketones with Aldehydes

BORTOLINI, Olga;FANTIN, Giancarlo;FERRETTI, Valeria;FOGAGNOLO, Marco;GIOVANNINI, Pier Paolo;MASSI, Alessandro;PACIFICO, Salvatore;RAGNO, Daniele
2013

Abstract

The hitherto unreported ability of the methylsulfinyl carbanion (dimsyl anion) to generate acyl anion equivalents is described. The dimsyl anion, in fact, efficiently catalyses chemoselective intermolecular cross- benzoin condensations of diaryl α-diketones (benzils) with various aromatic and aliphatic aldehydes to give the corresponding aryl-aryl and aryl-alkyl benzoin benzoates in an atom-economic fashion. The dimsyl anion acts as an environmentally friendly alternative to the toxic cyanide anion and it is obtained by in situ deprotonation of DMSO solvent with a catalytic amount of a strong base, being t- BuOK the optimal promoter. The assumption that the methylsulfinyl carbanion is the active catalyst in the title transformation is supported by electrospray ionization mass spectrometry (ESI-MS) experiments.
2013
Bortolini, Olga; Fantin, Giancarlo; Ferretti, Valeria; Fogagnolo, Marco; Giovannini, Pier Paolo; Massi, Alessandro; Pacifico, Salvatore; Ragno, Daniel...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/1871738
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