Studies on Tertiary Amine Oxides. XL. Reactions of Aromatic N-Oxides with Oxindoles in the Presence of Acylating Agents

Abstract

1-Methyloxindole (II) reacted as an active methylene compound with acyl-adducts of quinoline 1-oxides (I, IX and VIII), forming 1-methyl-3-(2- or 4-quinolyl)oxindoles (III, XV or XI). The reaction with I in the presence of acetic anhydride or benzoyl chloride further proceeded and gave bis-quinolyl compound (IV) besides mono-quinolyl one (III). The order of effectiveness of acylating agents was acetic anhydride>benzoyl chloride>tosyl chloride. Pyridine 1-oxide (XVII) itself was also able to react with II in hot acetic anhydride to give four kinds of products, 2-pyridyl- (XX), bis-2-pyridyl- (XIX), 4-pyridyl-product (XXI) and acetate of XXI (XVIII). The reaction of oxindole (XXVI) with I progressed similarly and 3-(2-quinolyl)-oxindole (XXVII) was obtained.