Synthesis of some novel azetidino[2,3-<i>b</i>][1,8]naphthyridin-2(1<i>H</i>)-ones and 1,2,4-triazolo [4,3<i>-a</i>][1,8] naphthyridines

Abstract

Ethyl 1,8-naphthyridin-2-one-3-carboxylate <b>1</b> on fusion with different anilines at 200°C affords <i>N</i>-aryl-1,8-naphthyridin-2-one-3-carboxamides <b>2</b>, which undergo smooth cyclization with POCl₃ yielding 1-arylazetidino [2,3-<i>b</i>][1,8]naphthyrid in-2(1<i>H</i>)-ones <b>3</b>.Compound <b>1</b> on treatment with POCl₃ yield ethyl 2-chloro-1,8-naphthyridine-3-carboxylate <b>4</b>, which on reaction with aromatic acid hydrazides in methanol furnishes respective <i>N</i>-aroyl-<i>N'</i>-(3- carbethoxy-1,8-naphthyridin-2-yl) hydrazines <b>5</b>. Cyclization of <b>5</b> with POCl₃ under reflux result in the formation of 1-aryl-4-carbethoxy-1,2,4-triazolof [4,3<i>-a</i>][1,8] naphthyridines <b>6</b>. Compounds <b>3</b> and <b>6</b> have been evaluated for their antibacterial activity using streptomycin as a reference compound.