Abstract
Treatment of 2-acetylindolinone (II) with acetic anhydride gives 1-acetyl-3-(1-acetyloxyethylidene)-2-indolinone (IV) whose catalytic reduction over palladium carbon affords 1-acetyl-3-ethyl-2-indolinone (V). Treatment of IV with ethanolic hydrochloric acid gives 3-(1-alkyloxyethylidene)-2-indolinone (VI) which reacts with acetic anhydride to produce 1-acetyl-3-(1-alkyloxyethylidene)-2-indolinone (VII). Reaction of VII with N-bromosuccinimide gives 1-acetyl-3-(1-methoxy-2-bromoethylidene)-2-indolinone (VIII). Catalytic reduction of VI affords 3-ethyl-2-indolinone (IX) which is also obtained on the reduction of II with lithium aluminum hydride. Catalytic reduction of II with platinum in acetic acid results in the formation of 3-ethyl-hexahydro-2-indolinone (XI). Exchange-decomposition of the acetyl group in II with alkyl group was carried out, and 3-ethyl compound (IX) and 3-ethoxycarbonylmethyl compound (XVI) were obtained but not isopropyl and tert-butyl compounds.
