Abstract

MUCHOWSKI, Joseph M.  and  MADDOX, Michael L.. 0-Hydroxylaminobenzaldehydes and the N-Acylated Derivatives Thereof. J. Mex. Chem. Soc [online]. 2005, vol.49, n.1, pp.24-31. ISSN 1870-249X.

Ethyl acetate solutions of o-hydroxylaminobenzaldehydes (1a, 8c, 8d) can be generated by reduction of the corresponding nitro compounds with zinc and ammonium chloride in a two phase ethyl acetate-water system at room temperature, but 2-nitro-3,6-dimethoxy-benzaldeyhde (4b) is converted into the anthranil 11 under these conditions. The N-acylated compounds derived from 1a and 8c exist exclusively as the cyclic tautomers (6a-c and 9a) in solution and in the solid state, whereas the N-acetyl compound 9b is in equilibrium with the open chain form 10 in solution, but only the cyclic form is present in the solid state. The N-acylated-o-hydroxylaminobenzalde-hydes undergo a novel internal redox reaction on thermolysis generating o-acylaminobenzoic acids which are converted into 2-substituted-4H-3,1-benzoxazin-4-ones (e.g., 6b→12b→13b) to a greater or lesser extent under the reaction conditions.

Keywords : O-hydroxyaminobenzaldehydes; reduction; anthranil; N-acyl; benzoxozinones.

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