Morales-Ríos, M. S., Rivera-Becerril, E., López-Camacho, P. Y., Pérez-Rojas, N. A., Suárez-Castillo, O. R. (2012). Preparation of O-Methyl Substituted 2-Oxofuro- and 2-Oxopyrrolidinoindolines by Reductive Lactonization of Oxindol-3-ylacetic Acids. Nat. Prod. Commun. 7, 1445-1451.
A practical procedure for the preparation of O-methyl substituted 3a,8-dialkyl-2-oxofuroindolines is described. Reductive lactonization of the corresponding oxindol-3-ylacetic acids provides a route for the formation of this class of compounds. Further transformation of 2-oxofuroindolines into 2-oxopyrrolidinoindolines, and then to pyrrolidinoindolines demonstrates their versatility as key intermediates in natural products synthesis. The results of single-crystal X-ray crystallographic analyses are given for five of the studied compounds.