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-oxindoles01775nas a2200157   4500008004100000022001400041245017300055210006900228260001100297300001400308490000700322520110800329100002401437700002601461856013001487       2021                        eng d  a1477-052000aFacile synthesis of indolizinoindolone, indolylepoxypyrrolooxazole, indolylpyrrolooxazolone and isoindolopyrazinoindolone heterocycles from indole and imide derivatives0 aFacile synthesis of indolizinoindolone indolylepoxypyrrolooxazol  cJUL 21  a6160-61690 v193 aChemo-, regio- and diastereoselective coupling reactions of indole with imide derivatives leading to unique heterocyclic systems are demonstrated. Acid-induced 3-position coupling reactions of indole with cyclic imide derived lactamols followed by acid promoted 2-position cyclizations with the corresponding aldehydes are described to obtain the indolizinoindolones and benzoindolizinoindolones. Base induced 2-position coupling reactions of N-tosylindole with N-(2-iodoethyl)imides and the subsequent cyclizations provide indolylepoxypyrrolooxazole, indolylpyrrolooxazolone and indolyloxazoloisoindolone. Reductive cleavage of indolyloxazoloisoindolone to the corresponding alcohol followed by mesylation and base promoted N-cyclization affords the in situ air-oxidized pentacyclic product hydroxyisoindolopyrazinoindolone. A regioisomeric structural revision of the natural product from 1,2,5,6,7,11c-hexahydro-3H-indolizino[7,8-b]indol-3-one to 1,2,5,6,11,11b-hexahydro-3H-indolizino(8,7-b)indol-3-one is also reported in the present studies focussed on the methodologies for heterocyclic synthesis.1 aShelar, Santosh, V.1 aArgade, Narshinha, P.  uhttps://library.ncl.res.in/content/facile-synthesis-indolizinoindolone-indolylepoxypyrrolooxazole-indolylpyrrolooxazolone-and01361nas a2200229   4500008004100000022001400041245013800055210006900193260000900262490000700271520053600278653001500814653001800829653002800847653001400875653002000889653002000909653002000929100002400949700002600973856013200999       2021                        eng d  a0039-788100aWittig reactions of maleimide-derived stabilized ylides with alkyl pyruvates: concise approach to methyl ester of (+/-)-chaetogline A0 aWittig reactions of maleimidederived stabilized ylides with alky  cAPR 0 v533 a<p>A facile synthesis of methyl ester of chaetogline A is reported starting from the corresponding methyl 1-methyltryptophanate-derived- maleimide. A stereoselective Wittig olefination with a carbonyl function in methyl pyruvate followed by phosphorous pentoxide-induced- regioselective dehydrative cyclization are the essential reactions. An acid-induced thermodynamically driven stereoselective beta- to alpha-position migration of the exocyclic C=C bond unit in ethyl tetrahydroindolizinoindolylidenepropanoate is described.</p>10aAmino acid10achaetogline A10adehydrative cyclization10amaleimide10amethyl pyruvate10aNatural product10aWittig reaction1 aShelar, Santosh, V.1 aArgade, Narshinha, P.  uhttps://library.ncl.res.in/content/wittig-reactions-maleimide-derived-stabilized-ylides-alkyl-pyruvates-concise-approach-methyl01076nas a2200145   4500008004100000245013700041210006900178260000800247300001600255490000700271520047500278100002600753700002400779856012700803       2021                        eng d00aWittig reactions of maleimide-derived stabilized ylides with alkyl pyruvates: concise approach to methyl ester of (±)-chaetogline A0 aWittig reactions of maleimidederived stabilized ylides with alky  cAPR  a2897–29020 v533 aA facile synthesis of methyl ester of chaetogline A is reported starting from the corresponding methyl 1-methyltryptophanate-derived­ maleimide. A stereoselective Wittig olefination with a carbonyl function in methyl pyruvate followed by phosphorous pentoxide-induced­ regioselective dehydrative cyclization are the essential reactions. An acid-induced thermodynamically driven stereoselective β- to α-position migration of the exocyclic C=C bond unit in ethyl… 
1 aArgade, Narshinha, P.1 aShelar, Santosh, V.  uhttps://library.ncl.res.in/content/wittig-reactions-maleimide-derived-stabilized-ylides-alkyl-pyruvates-concise-approach-0