Abstract
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.
Highlights
Sophisticated (Zhang et al 2017, Nadege et al 2016) or simple (Trost and Zhang 2006) natural compounds incorporating a 3,3-disubstituted 2-oxindole are frequently found (Kaur et al 2016, Saraswat et al 2016, Fonseca and Cook 2016, Ziarani et al 2013)
Continuing with our research looking for applications of this deacylative alkylation (DaA) for the synthesis of 3,3-dialkyloxindoles we describe here the synthesis of symmetrical 3,3-disubstituted analogues
After 4 h another addition of the same electrophile and base (1.5 equiv. each reagent) took place in order to complete the double alkylation mediated by the deacylative process, allowing the reaction to proceed at room temperature overnight
Summary
Sophisticated (Zhang et al 2017, Nadege et al 2016) or simple (Trost and Zhang 2006) natural compounds incorporating a 3,3-disubstituted 2-oxindole are frequently found (Kaur et al 2016, Saraswat et al 2016, Fonseca and Cook 2016, Ziarani et al 2013). It was recently demonstrated by our group than the monoalkylation of 3-acetyl-2-oxindoles 4 (Ortega-Martínez et al 2017) could be performed using alkyl halides and benzyltrimethylammonium hydroxide (Triton B) as base at room temperature in good yields. We have compared the results obtained through this DaA methodology versus the direct double alkylation of oxindole.
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