Enantioselective Rearrangement of Proline Sulfonamides: An Easy Entry to Enantiomerically Pure [alpha]-Aryl Quaternary Prolines
Written by Francesca Foschi, Dario Landini, Vittoria Lupi, Voichi[tcedil]a Mihali, Michele Penso, Tullio Pilati, Aaron Tagliabue on July 30, 2010 – 1:59 am -Enantiopure quaternary prolines have been prepared by stereoselective rearrangement of N-(arylsulfonyl)proline tert-butyl esters under basic conditions (see scheme), without any external source of stereochemical information. The sulfonamide aromatic ring must contain an electron-withdrawing group (EWG), which stabilizes an intermediate Meisenheimer complex. The overall process provides easy entry to a series of optically pure [alpha]-aromatic prolines.
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