Electrostatic Repulsion and Hydrogen‐Bonding Interactions in a Simple N‐Aryl‐L‐valinamide Organocatalyst Control the Stereoselectivity in Asymmetric Aldol Reactions. Issue 29 (2nd September 2013) - Tanimura, Yuya
Abstract: A novel stereocontrol method for asymmetric aldol reactions of aldehydes with ketones is described. The stereoselectivity of the products is controlled by the electrostatic repulsion and hydrogen‐bonding interactions of an N ‐aryl‐L ‐valinamide catalyst. The use of this catalyst in a cross‐aldol reaction allows easy access to bioactive 3‐cyclohexanone‐3‐hydroxy‐2‐oxindole with excellent diastereo‐ ( syn / anti = >99:1) and enantioselectivity (>99 % ee ). Abstract : Small, simple, and flexible N ‐(2, 6‐difluorophenyl)‐L ‐valinamide controls the stereoselectivity in asymmetric aldol and cross‐aldol reactions under environmentally friendly conditions. The use of this catalyst in a cross‐aldol reaction allows easy access to bioactive 3‐hydroxy‐3‐(2‐oxocyclohexyl)indolin‐2‐one with excellent diastereo‐ and enantioselectivities.