114679-01-5Relevant articles and documents
Electron-transfer-initiated benzoin- and Stetter-like reactions in packed-bed reactors for process intensification
Zaghi, Anna,Ragno, Daniele,Di Carmine, Graziano,De Risi, Carmela,Bortolini, Olga,Giovannini, Pier Paolo,Fantin, Giancarlo,Massi, Alessandro
, p. 2719 - 2730 (2016)
A convenient heterogeneous continuous-flow procedure for the polarity reversal of aromatic α-diketones is presented. Propaedeutic batch experiments have been initially performed to select the optimal supported base capable to initiate the two electron-tra
Cross-benzoin and Stetter-type reactions mediated by KO: T Bu-DMF via an electron-transfer process
Ragno, Daniele,Zaghi, Anna,Di Carmine, Graziano,Giovannini, Pier Paolo,Bortolini, Olga,Fogagnolo, Marco,Molinari, Alessandra,Venturini, Alessandro,Massi, Alessandro
, p. 9823 - 9835 (2016/10/31)
The condensation of aromatic α-diketones (benzils) with aromatic aldehydes (benzoin-type reaction) and chalcones (Stetter-type reaction) in DMF in the presence of catalytic (25 mol%) KOtBu is reported. Both types of umpolung processes proceed with good efficiency and complete chemoselectivity. On the basis of spectroscopic evidence (MS analysis) of plausible intermediates and literature reports, the occurrence of different ionic pathways have been evaluated to elucidate the mechanism of a model cross-benzoin-like reaction along with a radical route initiated by an electron-transfer process to benzil from the carbamoyl anion derived from DMF. This mechanistic investigation has culminated in a different proposal, supported by calculations and a trapping experiment, based on double electron-transfer to benzil with formation of the corresponding enediolate anion as the key reactive intermediate. A mechanistic comparison between the activation modes of benzils in KOtBu-DMF and KOtBu-DMSO systems is also described.
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
, p. 3244 - 3252 (2013/12/04)
The hitherto unreported ability of the methylsulfinyl carbanion (dimsyl anion) to generate acyl anion equivalents is described. The dimsyl anion, in fact, efficiently catalyzes 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 dimethyl sulfoxide (DMSO) solvent with a catalytic amount of a strong base, potassium tert-butoxide (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. Copyright