Safe prepn. of benzo:furazan-1-oxide(s) - from phase transfer reaction of a 2-nitroaniline and hypochlorite, useful as intermediates for antimicrobial cpds.

摘要

Benzofurazan-1-oxides (I) are prepd. by treating of a 2-nitroaniline (II) with MOCl (M = alkali metal) in a 2-phase solvent system (H2O and an H2O-immiscible solvent) in the presence of a phase-transfer catalyst (III): (where R1R2=H, halo, alkyl (opt. substd. by halo, OH, NH2 (and mono- and di-alkyl), alkoxy, alkylthio, alkoxycarbonyl, SO2NH2 or CONH2 (and N-alkyl and N,N-dialkyl derivs. of both(, CO2H, or CN, or one of R1R2 is a gp. (III), Z=H, halo, alkyl, alkoxy, alkylthio, CF3, n = 0-2, X =O,S,SO, or SO2, and all alkyl, alkoxy, etc. = 1-4C). Safe, phase-transfer reaction avoids the known hazards associated with the prepn. of (I) (formation of explosive hypochlorous acid esters, and the isolation of dried, thermally unstable (I)), and is acceptable ecologically. (I) are inters. for antimicrobial quinoxaline-1,4-dioxides and may be used in situ. in the solvent).