SYNTHESIS OF QUATERNARY INDOXYL DERIVATIVES BY INTRAMOLECULAR CYCLIZATION OF SOME SUBSTITUTED ACETOPHENONES

The intramolecular cyclization of N,N-disubstituted 2'-halogenophenacy lamine hydrobromides 1a-h to 1,1-disubstituted 3-oxoindolinium bromide s 3a-f has been studied. Some 3-oxoindolinium salts have also been pre pared according to a different pattern by intramolecular cyclization o f the phenacyl halides resulting from the bromination of 2'-(dialkylam ino)acetophenones 4 or from the treatment of 2'-(dialkylamino)-2-diazo acetophenones 6a, b with hydrogen halides. Removal of hydrogen halide in salts 3a-g gives indolylio oxides 2a-g; these compounds have been s hown to be unstable and decompose easily giving in general complex mix tures; only in the case of tetrahydroisoquinoline-derived ylides 2e, g we have observed clear-cut reactions leading, via a Stevens rearrange ment followed by oxidation, to the 6,7-dihydro-13H-indolo[2,1-b][3]ben zazepin-13-ones 8a, b.