First synthesis and further functionalization of 7-chloro-imidazo[2,1-b][1,3]thiazin-5-ones
作者:Clemens Lamberth、Florian Querniard
DOI:10.1016/j.tetlet.2008.02.014
日期:2008.3
A convenient four-step preparation route to novel 7-chloro-imidazo[2,1-b][1,3]thiazin-5-ones is presented, starting from methyl phenylglyoxylate. A unique feature of this synthesis is a heterocyclization strategy, in which a halogen atom is introduced already during the ring closure. 7-Chloro-6-phenyl-imidazothiazinones with a broad range of various substituents in the phenyl and imidazole moieties
从苯乙醛酸甲酯开始,提出了一种方便的四步制备路线,用于制备新型7-氯-咪唑并[2,1- b ] [1,3]噻嗪-5-酮。该合成的独特特征是杂环化策略,其中在闭环过程中已经引入了卤素原子。通过该方法可获得在苯基和咪唑部分中具有广泛的各种取代基的7-氯-6-苯基-咪唑并噻嗪酮,以及不同的氯化三唑并噻嗪酮。在亲核取代反应中,氯官能团很容易被氨基,烷氧基和芳硫基以及氟原子取代。
Synthesis of Tetrasubstituted Pyrazoles through Different Cyclization Strategies; Isosteres of Imidazole Fungicides
Formerly unknown 3-chloro-4,5-diaryl-1-methylpyrazoles have been prepared through two different synthesis pathways, one of which starts from 2,3-diarylacrylonitriles, the second from 3,3-dichloro-1,2-diarylpropenones. Both approaches rely on the cyclocondensation of diarylated three-carbon synthons with hydrazine derivatives and possess some unique features. One route uses a cyclization reaction, during which a chlorine atom is directly installed at the pyrazole ring that normally would be introduced in subsequent halogenation steps. The second pathway applies the Sandmeyer reaction to introduce this chloro substituent; an approach that is rarely described at the pyrazole nucleus. The obtained tetrasubstituted pyrazoles are isosteres of highly active imidazole fungicides and show good control of Uncinula necator (grape powdery mildew).