The reactions of 4-(1,2-dimethylindol-3-yl)butyric acid and of 3-(1,2-dimethylindol-3-yl)propionic acid with trifluoroacetic anhydride
Abstract
Treatment of 4-(1,2-dimethylindol-3-yl)butyric acid (1) with trifluoroacetic anhydride gives either 1-methyl-2-trifluoroacetylmethyleneindoline-3-spirocyclopentan-2′-one (6) or 1,2-dimethyl-6-oxo-3,4,5,6-tetrahydro-1H-cyclohept[c,d]indole (5) depending on the reaction conditions. 3-(1,2-Dimethylindol-3-yl)propionic acid (10;R = OH) reacts with trifluoroacetic anhydride to form 4,4a-dihydro-9-methyl-4a-[2,2,2-trifluoro-1-(2-hydroxy-9-methylcarbazol-3-yl)ethyl]carbazol-2(3H)-one (21).