Mild Nitration of Pyrazolin‐5‐ones by a Combination of Fe(NO
<sub>3</sub>
)
<sub>3</sub>
and NaNO
<sub>2</sub>
: Discovery of a New Readily Available Class of Fungicides, 4‐Nitropyrazolin‐5‐ones
作者:Igor B. Krylov、Alexander S. Budnikov、Elena R. Lopat'eva、Gennady I. Nikishin、Alexander O. Terent'ev
DOI:10.1002/chem.201806172
日期:2019.4.23
4‐Nitropyrazolin‐5‐ones have been synthesized by the nitration of pyrazolin‐5‐ones at room temperature by employing the Fe(NO3)3/NaNO2 system. The method demonstrated selectivity towards the 4‐position of pyrazolin‐5‐ones even in the presence of NPh and allyl substituents, which are sensitive to nitration. It was shown that other systems containing FeIII and nitrites, namely Fe(NO3)3/tBuONO, Fe(ClO4)3/NaNO2
通过使用Fe(NO 3)3 / NaNO 2体系在室温下硝化吡唑啉-5-酮合成了4-硝基吡唑啉-5-酮。即使存在对硝化敏感的NPh和烯丙基取代基,该方法也显示出对吡唑啉-5-酮的4位选择性。结果表明,其他含有Fe III和亚硝酸盐的体系,即Fe(NO 3)3 / t BuONO,Fe(ClO 4)3 / NaNO 2和Fe(ClO 4)3 / t BuONO,也是有效的。大概是铁三氧化亚硝酸盐(NaNO 2或t BuONO)形成NO 2自由基,作为吡唑啉-5-酮的硝化剂。已发现合成的4-硝基吡唑啉-5-酮是一类新的杀菌剂。发现它们对植物致病真菌的体外活性与商业杀真菌剂(氟康唑,克霉唑,三唑酮和克雷索肟)相当甚至更好。这些结果为开发新型植物保护剂提供了一个有希望的起点,这种保护剂可以很容易地从广泛使用的试剂中合成。