Palladium-Catalyzed Synthesis of 3,3-Disubstituted Oxindoles

Significance

Formation of a minor product during optimization of a palladium-catalyzed stereoselective synthesis of 3-(alkoxyalkylidene)oxindoles (T. Miura, T. Toyoshima, Y. Ito, M. Murakami Chem. Lett. 2009, 38, 1174) led to the present work. Using the same starting materials, for example, 2-(alkynyl)arylisocyanates 1 and benzyl alcohols, the synthesis of 3,3-disubstituted oxindoles 2 has been achieved in moderate to good yield using CpPd(π-allyl) as catalyst and toluene as solvent. The reaction was extended to allyl alcohols, for which the reaction times and temperature were respectively shorter and lower. When the equivalents of allylic alcohol and the reaction time are increased, N-allylated 3,3-disubstituted oxindoles 4 are obtained in good yields.