Chemical oxidation of a series of sydnonimine derivatives followed by NO release was studied. Substances having alkylamine substituents in the position 3 were shown to be consid erably more potent NO donors in comparison with those having alkyl or aralkyl substituents in the position 3. It was suggested that the effect is mainly due to lowering of the activation energy of NO release upon stabilization of the cation formed competitevely by the amino group.

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Oxadiazole derivatives R 0290Sydnonimines as Exogenous NO Donors -[properties of sydnonimines (I) as nitrogen oxide donors]. -(KHMEL'NITSKAYA, E. Y.; LEVINA, V. I.; TRUKHACHEVA, L. A.; GRIGORIEV, N. B.; KALININ, V. N.; CHEREPANOV, I. A.; LEBEDEV, S. N.; GRANIK*, V. G.; Russ.

On heating at pH 6.86, 4 (N,N dialkylthiocarbamoylthio) 5 nitropyrimidines are trans formed into dithiolopyrimidines, which are either oxidized to bis(4 dialkylthiocarbamoyl pyrimidin 5 yl) disulfides or converted into 4,6 diamino 5 nitropyrimidine derivatives with carbon disulfide elimination. The direction of the reaction is determined by the nature of a substituent in position 2 of pyrimidine and the bulk of the thiocarbamate substituent. Mecha nistic schemes for these processes were proposed.

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