An Arginine‐Mediated Protocol for the Aldol Addition of Methyl Vinyl Ketone in Water.

Abstract: An aldolisation protocol for methyl vinyl ketone has been developed using an arginine mediated reaction in water. The reaction brought out an interesting contrast to the reactivity of methyl vinyl ketone with two different amino acids proline and arginine under nearly identical conditions. The aldolisation was only moderately effective with aromatic aldehydes as acceptors, but proved quite efficient when isatins were used. The latter underwent a rapid aldol addition with methyl vinyl ketone at room temperature under aqueous conditions to provide an expedient access to the corresponding 3‐substituted‐3‐hydroxyindolin‐2‐ones in good yields. These adducts were further transformed in ways characteristic to the β‐unsubstituted activated olefin moiety. The method also helped access a spirooxindole pyranone in reasonable yield. [ABSTRACT FROM AUTHOR]