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

Abstract

A one-step, three-component Petasis reaction of isatin derived 5-arylboronate-3-substituted oxindole derivatives with salicylaldehydes and secondary amines affords new enan- tiomerically pure structurally diverse 5-α-(3-substituted-oxind- ole)-benzylamine derivatives. The reaction shows good sub- strate and reagent scope affording the products with good to excellent yields (up to >99 % yield) and enantioselectivities (upto 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), excel- lent enantioselectivities (up to 99 % ee) and good diastereo- selectivities (up to 86 % de) were obtained for new 5-α-(3- hydroxy-oxindole)-benzylamine derivatives, having two stereo- centers. The reaction is also feasible on gram-scale.