Pyrrolidine-2,3-diones, 1,5-diaryl

Infrared and ultraviolet spectral data indicate that 1,5-diaryl-pyrrolidine-2,3-diones exist in the monooxo form 68. Chemical evidence was advanced for a tautomeric equilibrium between 69 and 70, and later spectroscopic work showed that 70 was the predominant form. " Compounds of type 71 were formulated, without experimental evidence, in the oxo-imino form, although the tendency for C=NR—>C—NHR is usually greater than that for C=0—>C—OH in analogous cases. 

IV-acetyl pyrrolidines and -piperidines to the corresponding diones or ketones were similarly effected [405, 406], as were conversions of diacetyl and dibenzyl piperazines to diketo componnds by the same system (Table 5.1) [407]. Methylene groups adjacent to the N atom in tertiary polycyclic amines were oxidised by RuO /aq. NaCIO j/CCl (Fig. 5.5) [408]. A large-scale oxidation of l,4-bis(2-phenylethyl) piperazine to the dione was made by RnO /aq. Na(10 )/Et0Ac [409], and RuO /aq. Na(IO )/CCl converted dialkyl or diaryl A A -dimethyladenosines to the corresponding monoamido derivatives (Fig. 5.4) [410]. 

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