N-Acetyl-2-nitrodiphenylamine類のTriethyl Phosphiteによる還元スピロ5員環中間体を経るDihydrophenazine類の生成

概要

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Reductive cyclization of N-acetyl-2'-methylthio-2-nitrodiphenylamine (I) with triethyl phosphite led to the formation of 5-acetyl-1-methylthio-5,10-dihydrophenazine (II), 5-acetyl-5,10-dihydrophenazine (III), 2-methyl-1-(2'-methylthiophenyl)-benzimidazole (IV), 1-methylthiophenazine (V), and phenazine (VI). A similar treatment of N-acetyl-4-chloro-2'-methylthio-2-nitrodiphenylamine (VII) afforded 5-acetyl-8-chloro-1-methylthio-5,10-dihydrophenazine (VIII), and 5-acetyl-8-chloro-5,10-dihydrophenazine (IX) as major products. VIII was easily converted by autooxidation to 8-chloro-1-methylthio-phenazine (X). Structure X was distinguished from an alternative structure (X') based on the physicochemical comparison with X', which was prepared unequivocally from VII by irradiation followed by reduction. These results made it possible to propose that the formation of dihydrophenazines involved a novel molecular rearrangement via a five-membered spiro-intermediate, and sigmatropic and prototropic rearrangements.
公益社団法人日本薬学会の論文
1972-11-25