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[摘要]:A general protocol for the synthesis of substituted 5-aminotetrazoles by treating cyanogen azide with primary allylamines afforded either by S(N)2 or S(N)2 ' reactions of Morita-Baylis-Hillman acetates of acrylate has been developed. The base-promoted intramolecular cyclizations of these tetrazoles afford highly substituted 2-azidopyrimidin-4(3H)-ones instead of the expected tetrazolopyrimidinone due to azide tetrazole tautomerism. Nevertheless it has been discovered that substituted tetrazolo[1,5-a]pyrimidin-7(4H)-ones could be isolated in pure form from a methanolic solution of the respective 2-azidopyrimidin-4(3H)-ones through crystallization. The structure of tetrazolo[1,5-a]pyrimidin-7(4H)-one was unambiguously assigned by X-ray crystallography. The existence of azide tetrazole tautomerism in this class of compounds has been supported through NMR spectroscopic studies. |
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