Synthesis of 1,3-Di[alkoxy(aryloxy)carbonyl]-2-oxo-2,3-dihydroindoles

Two protocols have been developed for the synthesis of 1,3-di[alkoxy(aryloxy)carbonyl]-2-oxo-2,3-dihydroindoles starting from the corresponding N,O-diacyl derivatives obtained by treatment of 2-oxindoles with chloroformic acid esters and triethylamine. The first is rearrangement of N,O-diacylated compounds in the presence of 4-dimethylaminopyridine to give N,C(3)-diacylated products with identical acyl groups in the two positions. The second involves O-deacylation of the N,O-diacylated compounds, followed by O-acylation and rearrangement resulting N,C(3)-diacylated 2-oxindoles with different acyl groups in the two positions.