1,2-nucleophilic addition on 2-phenyl-3H-indol-3-one and 2-phenyl-3-phenylimino-3H-indole and their corresponding 1-oxides. An attempt to synthesize water-soluble aminoxyls. Crystal structure of 3-ethoxycarbonyl-2,3,3a,4-tetrahydro-2,4-dioxo-3a-phenylisoxazolo[2,3-a]indole

3-Indolinonic (1a) and 3-phenyliminoindolinonic (1b) 1-oxides react at carb on 2 with diethyl malonate and ethyl acetoacetate anions, yielding intermed iate anions which undergo cyclization in the reaction medium to form an iso xazolidine ring. The cyclization occurs through the interaction of the oxyg en of the primitive N-oxide function with a carbonyl group of the reagents. The same substrates react with dilithium phenylacetate anion, leading to t he formation of stable and water-soluble carboxylated aminoxyls. The indole nin-3-one 2a and its corresponding 3-phenylimino derivative 2b also react w ith the above-mentioned nucleophiles to form carboxylated 3-indoxyls withou t cyclization; oxidation with m-chloroperbenzoic acid does not yield carbox ylated aminoxyls in appreciable amount. The structure of the product of cyc loaddition obtained from the reaction of compound la with diethyl malonate was determined by X-ray analysis.