Tele nucleophilic aromatic substitutions in 1-nitro-3-and 1,3-dinitro-5-trichloromethylbenzene, and 3-trichloromethylbenzonitrile. A new synthesis ofthe 1,4-benzothiazine-3(4H)-one ring system from 3-nitrobenzoic acid

3-Trichloromethylnitrobenzene 2, 1,3-dinitro-5-trichloromethylbenzene 13 an d 3-trichloromethylbenzonitrile 18 react with sodium methoxide to give 4-me thoxy-3-nitrobenzaldehyde 6, 4-methoxy-3,5-dinitrobenzaldehyde 15 and 5-dim ethoxymethyl-2-methoxybenzonitrile 19, respectively. Compounds 2 and 13 rea ct with methyl thioglycolate to afford dichloromethylacetates 7 and 16, res pectively. These products are the result of tele nucleophilic aromatic subs titution. Compound 18 reacted with methyl thioglycolate to give acetate 20 resulting from nucleophilic displacement of cyanide. Reductive cyclisation of 7 afforded benzothiazine 11. (C) 2000 Elsevier Science Ltd. All rights r eserved.