Accessing New 5-α-(3,3-Disubstituted Oxindole)-Benzylamine Derivatives from Isatin: Stereoselective Organocatalytic Three Component Petasis Reaction

A one-step, three-component Petasis reaction of isatin derived 5-arylboronate-3-substituted oxindole derivatives with salicylaldehydes and secondary amines affords new enantiomerically pure structurally diverse 5-α-(3-substituted-oxindole)-benzylamine derivatives. The reaction shows good substrate and reagent scope affording the products with good to excellent yields (up to >99 % yield) and enantioselectivities (up to 99 % ee) using cheap and readily available (R)-BINOL as the organocatalyst. A diastereoselective version of the reaction was also developed where moderate yields (37 to 55 % yield), excellent enantioselectivities (up to 99 % ee) and good diastereoselectivities (up to 86 % de) were obtained for new 5-α-(3-hydroxy-oxindole)-benzylamine derivatives, having two stereocenters. The reaction is also feasible on gram-scale.