Quinine as an organocatalytic dual activator for the diastereoselective synthesis of spiro-epoxyoxindoles
摘要:
A highly efficient organocatalytic approach has been developed for the diastereoselective epoxidation of (E)-3-ylidene-indolin-2-one derivatives using readily available natural product quinine and urea-hydrogen peroxide (UHP) in DCM at 10 degrees C to afford trans spiro-epoxyoxindoles which were further utilized to obtain beta-hydroxy-alpha-amino esters by water mediated regioselective ring opening from the less hindered end with aniline derivatives, under sonication. (C) 2013 Elsevier Ltd. All rights reserved.