A Mild and Efficient Synthesis of Oxindoles: Progress Towards the Synthesis of Welwitindolinone A Isonitrile

Abstract

The complete carbon skeleton of welwitindolinone A isonitrile has been prepared by using a [2+2] cycloaddition to establish the bicyclo[4.2.0]octane core and a SmI2-mediated intramolecular reductive cyclization between an enone and an aryl isocyanate to stereoselectively install the spiro-oxindole (see scheme; DBU=1,8-diazabicyclo[5.4.0]undec-7-ene).