Stereoselective Oxidative Rearrangement of 2-Aryl Tryptamine Derivatives

The oxidation of 2-aryl tryptamines followed by a stereoselective rearrangement provides a versatile strategy for the synthesis of C3-quaternary oxindoles bearing a C3-aryl group. Treatment of optically active 2-aryl hydroxyindolenines with scandium trifluoromethanesulfonate in toluene at 110 °C leads to complete and stereoselective isomerization to the corresponding C3-aryl oxindoles which represent versatile intermediates for the synthesis of C3a-aryl hexahydropyrroloindoles.