Abstract
In connection with studies on pyrolysis of 3, 3-disubstituted 1-acyl-indolin-2-ylpyridinium chloride, 1) 2, 3, 3-trisubstituted 1-acyl-indolin-2-ylpyridinium chlorides (Ia-c) were analogously pyrolyzed in boiling pyridine. Of the compounds treated, only derivatives holding a methyl substituent at position 2 (Ib, c) underwent pyrolysis giving 3, 3-disubstituted 1-(p-chlorobenzoyl)-2-methylene-indoline (IIb, c). During the isolation of IIb and IIc, 1-(p-chlorobenzoyl)-2, 3-dimethyl-3-phenylindolin-2-ol (IVb) and 3-[2-(p-chlorobenzoyl-anilino)]-3-methyl-2-butanone (IIIc) were respectively found in the reaction mixture. The tautomeric character of these compounds (IVb and IIIc) existing in the indolin-2-ol and its ring opening structures in solution was discussed. Additionally, this report involves a correction of the product in the Friedel-Crafts reaction of 1-benzoyl-2-chloro-3, 3-dimethyl-indoline with benzene reported by Leuchs.3)
