- Reactions of N,N-bis(siloxy)enamines with trimethylsilyl cyanide: Aliphatic nitro compounds as convenient precursors of 5-aminoisoxazoles
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A convenient procedure was developed for the synthesis of 5-aminoisoxazoles by the consecutive double silylation and cyanation of aliphatic nitro compounds.
- Lesiv, Aleksei V.,Ioffe, Sema L.,Strelenko, Yurii A.,Bliznets, Igor' V.,Tartakovsky, Vladimir A.
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- Isoxazoles. VII: Hydrolysis of 4-methyl-5-isoxazolylnaphthoquinone derivatives in aqueous solutions
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The kinetics for the degradation of 2-(4-methyl-5-isoxazolylamine)-N-(4-methyl-5-isoxazolyl)-1,4- naphthoquinone-4-imine (1) in solution were investigated at 70 °C and at a constant ionic strength of 0.5 over a pH range of 1.75 to 12.85. The degradation rates were determined by absorption and second-derivative UV spectrometry. Two degradation products were identified in acidic and neutral pHs; they are 4-N-(4-methyl-5-isoxazolyl)-1,2-naphthoquinone (2) and 2-methyl-cyanoacetamide (5), respectively. In alkaline pH, two degradation products, 2-hydroxy-N-(4-methyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (3) and 5-amino-4-methylisoxazole (4), were isolated. The pathway for degradation of 1 in acidic and neutral pH followed consecutive first-order kinetics since 2 undergoes hydrolysis giving 2-hydroxy-1,4-naphthoquinone (6) and 2-methylcyanoacetamide (5). No appreciable buffer effect on the degradation of 1 and 2 was observed for any of the buffer species in this study. The pH-rate profiles exhibited specific acid and specific basic catalysis for 1 and specific acid catalysis for 2. The maximum stability for 1 and 2 occurred in the neutral pH region.
- Longhi,De Bertorello,Brinon
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p. 573 - 577
(2007/10/02)
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