- Dienophilicity of imidazole in inverse electron demand Diels-Alder reactions: Cycloadditions with 1,2,4,5-tetrazines and the structure of zarzissine
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The inverse electron demand cycloadditions of 2-substituted imidazoles with dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate produced imidazo[4,5-d]pyridazines in good yields. This chemistry was applied to the synthesis of 2-amino-1H-imidazo[4,5-d]pyridazine (1), the structure reported for zarzissine, a cytotoxic marine alkaloid. Differences in the 1H- and 13C NMR spectra of 1 with those reported for zarzissine necessitated a structural revision, and zarzissine was then considered to be the corresponding 2-amino-1H-imidazo[4,5-b]pyrazine (2), which was subsequently synthesized from the parent heterocycle.
- Wan, Zhao-Kui,Woo, Grace H.C.,Snyder, John K.
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p. 5497 - 5507
(2007/10/03)
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- 2-Substituted-1,2,4-thiadiazolo-[2,3-a]-imidazoles
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Novel 2-substituted-1,2,4-thiadiazolo-[2,3-a]-imidazoles of the formula SPC1 And the pharmaceutically acceptable salts thereof; and process for their preparation. These 2-substituted-1,2,4-thiadiazolo-[2,3-a]-imidazoles are useful as fungistatic and fungi
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