Facile synthesis of fused quinolines via intramolecular Friedel-Crafts acylation

Abstract

The intramolecular cyclisation of 6-[(phenoxy/phenylthio)methyl][1,3] dioxolo[4,5-g]quinoline-7-carboxylic acids to [1]benzoxepino[3,4-b][1,3] dioxolo[4,5-g)quinolin-12(6H)-onesand[1]benzothiepino[3,4-b)][1,3]dioxolo[4,5-g] quinolin-12(6H)-ones in the presence of Baton's reagent (P2O 5-MeSO3H) is described. This cyclisation protocol requires milder conditions than those traditionally employed and is characterised by relatively low reaction temperatures and ease of product isolation.