Highly enantioselective aldol reaction of acetaldehyde and isatins only with 4-hydroxydiarylprolinol as catalyst: concise stereoselective synthesis of (R)-convolutamydines B and E, (-)-donaxaridine and (R)-chimonamidine

A highly enantioselective aldol reaction of acetaldehyde and a wide scope of isatins has been presented only using readily available 4-hydroxydiarylprolinol as catalyst, affording various desired 3-substituted 3-hydroxyindolin-2-one adducts with moderate to high yield (up to 95%) and good enantioselectivities (up to 98% ee). This method not only represents an example of concise stereoselective synthesis of enantiopure (R)-convolutamydines B and E, but also firstly exhibits expedient asymmetric synthesis optically active (-)-donaxaridine and (R)-chimonamidine. (C) 2009 Elsevier Ltd. All rights reserved.