Isothiazolo-fused quinoline analogues: Synthesis of isothiazolo [5, 4-b] quinolines and their oxidation products, 3[2H]-one-1, 1-dioxideisothiazolo [5, 4-b] quinolines from 2-chloro-3-formylquinolines

Abstract

A convenient synthesis of isothiazolo[5,4-b]quinolines 2 is achieved in two steps from the reaction of 2-chloro-3-formylquinolines 1 with sodium sulfide and hydroxylamine sequences followed by cyclisation with acetic anhydride. The subsequent oxidation of 2 with H₂O₂ in acetic acid yields 3(2H)-one-1, 1-dioxideisothiazolo [5, 4-b] quinolines 3.