01154nas a2200157   4500008004100000022001400041245005500055210005400110260000800164300001400172490000700186520066900193100002400862700002600886856008400912       2019                        eng d  a1477-052000aRegioselective oxidation of indoles to 2-oxindoles0 aRegioselective oxidation of indoles to 2oxindoles  cJUL  a6671-66770 v173 a<p>Facile regioselective oxidation of indoles to 2-oxindoles promoted by sulfuric acid adsorbed on silica gel is reported. The demonstrated practical site-selective heterogeneous oxidation reactions conveniently take place with a broad substrate scope and functional group tolerances. The present oxidation strategy is also employed to accomplish the total synthesis of natural products donaxaridine and donaxarine. On the basis of analytical and spectral data it is evidenced that donaxarine stays in equilibrium with its hydrated ring opened form. The structural features essential for this type of oxidation and plausible mechanism are discussed in brief.</p>
1 aShelar, Santosh, V.1 aArgade, Narshinha, P.  uhttps://library.ncl.res.in/content/regioselective-oxidation-indoles-2-oxindoles