Deacylative alkylation (DaA) of N-methyl-3-acetyl-2-oxindole for the synthesis of symmetrically 3,3-disubstituted 2-oxindoles. An access gate to anticancer agents and natural products

The synthesis of 3,3-disubstituted N-methyloxindoles, starting from 3-acetyl-2-hydroxy-1-methyloxindole employing a sequential one-pot synthesis, is studied. The process involves a first alkylation in the presence of 1 equiv. of both organic halide and Triton B and the second one employs another 1.5 equiv. of each in moderate to high yields. This procedure is compared with the results obtained from the direct dialkylation of N-methyloxindole. The metathesis of one of the corresponding diallylated product was also studied obtaining the spiranic oxindole. All these methodologies are directed towards the access to anticancer agents and natural biologically active products.