Synthesis of fluorophenothiazines via Smiles rearrangement and their conversion into sulfones

The synthesis of 3-fluoro-1-methylphenothiazines and 7-fluoro-9-methylnitrophenothiazines is reported. 3-Fluoro-1-methylphenothiazines have been prepared by Smiles rearrangement of 5-fluoro-3-methyl-2-formamido-2-nitrodiphenyl sulfides in alcoholic potassium hydroxide solution. The formyl derivatives were prepared by the formylation of resultant diphenyl sulfides obtained by the condensation of 2-amino-5-fluoro-3-methylbenzenethiol with o-halonitrobenzenes in ethanolic sodium acetate solution. 7-Fluoro-9-methylnitrophenothiazines have been prepared by the condensation of 2-amino-5-fluoro-3-methylbenzenethiol with o-halonitrobenzenes containing nitro group (sS) Or one nitro and halogen atom at both ortho positions to the reactive halogen atom in ethanolic sodium hydroxide solution where Smiles rearrangement occurs in situ. Fluorinated sulfones have been synthesized by the oxidation of fluorinated phenothiazines by 30% hydrogen peroxide in glacial acetic acid, (C) 1999 Elsevier Science S.A. All rights reserved.