Azimines, azo-aziridines, 1,2,3-triazoles. Products obtained from the oxidation of N-aminophthalimide in the presence of azo-alkenes

Oxidation of N-aminophthalimide with lead tetraacetate carried out in the presence of an olefinic substrate gives rise to the formation of N-aminoaziridine derivatives [1-5]. It is well accepted that 1,1-disubstituted aminonitrenes can be generated by the oxidation of the corresponding 1,1-disubstituted hydrazines, this reaction has been considered as an aminonitrene cycloaddition to C=C-bonds [1-3]. More recently, Atkinson et al. [4] as well as others [5, 6] have shown and discussed that lead tetraacetate oxidation of N-aminophthalimide and related N-aminoheterocycles involves the N-acetoxyhydrazine intermediate rather than the N-aminonitrene. Regardless of the actual type of intermediate, the "oxidative aminoaziridination" is a convenient method for the synthesis of N-aminoaziridines.

Lead tetraacetate oxidation of N-aminophthalimide in the presence of azo compounds affords phthalimidoazimines, a new class of 1,3-dipolar species [2,3,7].

Azo-alkenes (a,b-unsaturated azo compounds) [8] containing both functional groups aroused our interest to investigate the chemoselectivity of this reaction. To this goal, N-aminophthalimide was oxidized with lead tetraacetate in the presence of several azo-alkenes.

Scheme 1 Oxidation of 1,1-disubstituted hydrazines in the presence of olefins and azo compounds: N-aminoaziridines and azimines

Scheme 2 Azo-alkenes; syntheses

Scheme 3 (E)-b-Phenylazo-stilbene, N-aminophthalimide, lead tetraacetate: 2-phenyl-3-phenylazo-1-phthalimidoaziridine

Scheme 4 (E)-1-phenylazo-1-cyclohexene, N-aminophthalimide, lead tetraacetate: syn-2-phenylazo-1-phthalimidoperhydrocyclohexa[b]aziridine

Scheme 5 (E)-1-phenylazo-1-cyclopentene, N-aminophthalimide, lead tetraacetate: 2-phenyl-2,4,5,6-tetrahydrocyclopenta[d][1,2,3]triazole

Scheme 6 (E)-2-phenylazo-propene, N-aminophthalimide, lead tetraacetate: 4-methyl-2-phenyl-1,2,3-triazole and phthalimide and

(2-phenylhydrazonopropylideneamino)phthalimide [via ene-azimine?]

Scheme 7 3,3,5-Trimethyl-3H-pyrazole, N-aminophthalimide, lead tetraacetate: (E)- and (Z)-3,3,5-trimethyl-3H-pyrazolium-2-(phthalimido)imide and (Z)-3,3,5-trimethyl-3H-pyrazolium-1-(phthalimido)imide

     

References

1. B.V. Ioffe, M.A. Kuznetsov, A.A. Potekhin, "Chemistry of the Organic Hydrazine Derivatives" Khimiya, Leningrad, 1979, p. 224.
2. R.S. Atkinson in "Azides and Nitrenes. Reactivity and Utility" ed. E.F.V. Scriven, Academic Press, New York, 1984, p. 247.
3. M.A. Kuznetsov, B.V. Ioffe, Uspekhi Khimii, 1989, 58, 1271; Russ. Chem. Rev., 1989, 58, 732.
4. R.S. Atkinson, B.J. Kelly, J. Chem. Soc., Chem. Commun. 1987, 1362.
5. D.W. Jones, M. Thorton-Pett, J. Chem. Soc., Perkin Trans. 1 1995, 809.
6. R.S. Atkinson, E. Barker, J. Chem. Soc., Chem. Commun., 1995, 819.
7. A.A. Suvorov, M.A. Kuznetsov, Uspekhi Khimii, 1987, 56, 1324; Russ. Chem. Rev. 1987, 56, 756.
8. J.G. Schantl in Houben-Weyl, "Methoden der Organischen Chemie" vol. E15, Georg Thieme, Stuttgart-New York, 1993, 909.