3H-Indoleの研究(第1報)Oxindole, Indolineを経る3,3-ジ置換3H-Indoleの新合成法

抄録

3-Monosubstituted oxindole (4) was converted to 3, 3-disubstituted 1-acetyl-oxindole (1') by acetylation with boiling acetic anhydride followed by alkylation with sodium hydride and alkyl halide in refluxing tetrahydrofuran. The product was saponified in ethanolic potassium hydroxide to 3, 3-disubstituted oxindole (1). 1 was reduced with lithium aluminum hydride or sodium dihydro-bis (2-methoxyethoxy) aluminate to 3, 3-disubstituted indoline (2). To convert the indolines (2) thus obtained to the 3H-indoles (3) ; various oxidizing agents were examined. As a result, dehydrogenation by refluxing with activated manganese dioxide in anhydrous toluene was found to be generally useful for this purpose.