Unusual reaction proceeding via the electrophilic activation of nitroalkanes in the presence of polyphosphoric acid has been discovered. Subsequent nucleophilic attack with semicarbazides or thiosemicarbazides allows to access 2-amino-1,3,4-oxadiazoles and 2-amino-1,3,4-thiadiazoles, respectively.

中文翻译：

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通过亲电活化的硝基烷烃的化学选择性缩合为（硫代）氨基脲或硫酰肼制备1,3,4-恶二唑和1,3,4-噻二唑

已经发现在多磷酸存在下经由硝基链烷的亲电活化进行的异常反应。随后用氨基脲或硫代氨基脲的亲核攻击使得可以分别接近2-氨基-1,3,4-恶二唑和2-氨基-1,3,4-噻二唑。