Novel Cyclization of Vinyl Nitrene into 1-Azaphenalene
摘要:
研究了在氮丙啶环附近带有甲氧基或甲硫基的 2H-氮丙啶的热反应。在2-(2-甲氧基萘-1-基)-2H-吖丙啶-3-羧酸乙酯的热解中,观察到乙烯基氮烯在周围位置的攻击,形成1-氮杂菲那烯环。在其硫代类似物的热反应中,也形成1-氮杂菲那烯,但主要产物是乙烯基氮烯攻击硫原子形成的萘并噻嗪。讨论了取决于 O 和 S 的反应机理和差异。
Catalyst-Free Preparation of 1,2,4,5-Tetrasubstituted Imidazoles from a Novel Unexpected Domino Reaction of 2-Azido Acrylates and Nitrones
作者:Bao Hu、Zhao Wang、Ning Ai、Jie Zheng、Xing-Hai Liu、Shang Shan、Zhongwen Wang
DOI:10.1021/ol202650z
日期:2011.12.16
A highly efficient and convenient method for the synthesis of 1,2,4,5-tetrasubstitutedimidazoles from readily accessible 2-azidoacrylates and nitrones has been developed. This reaction proceeded under mild conditions without the assistance of any metal, acid, or base.
One-pot synthesis of 1,2,4,5-tetrasubstituted imidazoles by a tandem three-component reaction of hydroxylamines, aldehydes and 2-azido acrylates
作者:Bao Hu、Ning Ai、Zhao Wang、Xiaoliang Xu、Xiaonian Li
DOI:10.3998/ark.5550190.0013.621
日期:——
The reaction of nitrones, formed in situ by reaction of hydroxylamines and aldehydes, with 2azido acrylates results in the formation of 1,2,4,5-tetrasubstitutedimidazoles has been developed. This three-componentreaction allows for the formation of a diverse array of imidazole derivatives with moderate to excellent yields.
A compound of the formula
1
wherein the substituents are defined as in the specification and salts or hydrates thereof is disclosed as well as a method of treating disorders associated with the inactivation or excessive degradation of cholecystokinin.
In the Hemetsberger-Knittel reaction for indole synthesis, the intermediate ethyl 2-azido-3-hydroxy-3-aryl-propionate (4) was found to be formed in the reaction of arylaldehyde 1 with ethyl azidoacetate at a lower temperature (-30°C) as the main product, while only ethyl 2-azidocinnamate (2) is known to be formed at a higher temperature (0°C). It was also found that fluoride ion was effective for obtaining 4. Compound 4 was converted to 2 in good yield by treatment with SOCl2/pyridine or SOCl2/Et3N. A trial application of this reaction to ketone is also described.
Thermal reaction of 2H-azirines, bearing a methoxy or methylthio group at the neighboring position to azirine ring, was studied. In thermolysis of ethyl 2-(2-methoxynaphth-1-yl)-2H-azirine-3-carboxylate, attack of the vinyl nitrene at the peri position to form a 1-azaphenalene ring was observed. In thermal reaction of its thio analogue, 1-azaphenalene was also formed, but a naphthothiazine formed by the attack of vinyl nitrene at the sulfur atom was the major product. Mechanisms and differences of the reactions depending on O and S are discussed.
研究了在氮丙啶环附近带有甲氧基或甲硫基的 2H-氮丙啶的热反应。在2-(2-甲氧基萘-1-基)-2H-吖丙啶-3-羧酸乙酯的热解中,观察到乙烯基氮烯在周围位置的攻击,形成1-氮杂菲那烯环。在其硫代类似物的热反应中,也形成1-氮杂菲那烯,但主要产物是乙烯基氮烯攻击硫原子形成的萘并噻嗪。讨论了取决于 O 和 S 的反应机理和差异。