114679-00-4Relevant academic research and scientific papers
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.
Palladium-Catalyzed Chemo- and Enantioselective C?O Bond Cleavage of α-Acyloxy Ketones by Hydrogenolysis
Chen, Jianzhong,Zhang, Zhenfeng,Liu, Delong,Zhang, Wanbin
supporting information, p. 8444 - 8447 (2016/07/19)
A chemoselective C?O bond cleavage of the ester alkyl side-chain of α-acyloxy ketones was realized for the first time by a highly efficient palladium-catalyzed hydrogenolysis (S/C=6000, the highest catalytic efficiency by far). Furthermore, a kinetic resolution of α-acyloxy ketones was first developed by enantioselective hydrogenolysis with good yields and up to 99 % ee.
One-pot, two-step desymmetrization of symmetrical benzils catalyzed by the methylsulfinyl (dimsyl) anion
Ragno, Daniele,Bortolini, Olga,Giovannini, Pier Paolo,Massi, Alessandro,Pacifico, Salvatore,Zaghi, Anna
, p. 5733 - 5744 (2014/07/22)
An operationally simple one-pot, two-step procedure for the desymmetrization of benzils is herein described. This consists in the chemoselective cross-benzoin reaction of symmetrical benzils with aromatic aldehydes catalyzed by the methyl sulfinyl (dimsyl) anion, followed by microwave-assisted oxidation of the resulting benzoylated benzoins with nitrate, avoiding the costly isolation procedure. Both electron-withdrawing and electron-donating substituents may be accommodated on the aromatic rings of the final unsymmetrical benzil. the Partner Organisations 2014.
A New Site Selective Synthesis of Benzoin Esters. Synthesis of Symmetrically and Unsymmetrically Substituted Benzils
Armesto, Diego,Horspool, William M.,Ortiz, Maria J.,Perez-Ossorio, Rafael
, p. 799 - 801 (2007/10/02)
A series of novel benzoin esters has been obtained in high yield, in a site selective synthesis, by the acid hydrolysis of a series of 4-benzoyloxy-2-azabuta-1,3-dienes.The oxidation of the benzoin esters allows the preparation of symmetrically and unsymmetrically substituted benzils by a route that is superior, in some cases, to those previously reported.
