研究了使用周期系统的第4组(Zr和Hf)和第5组(V,Nb,Ta)元素对1,4-二氢吡啶(1,4-DHPs)进行的芳构化。在室温下与VOCl 3在二氯甲烷中的反应以高至优异的产率提供了产物,取代的吡啶。首次在电子转移之前的1,4-DHP和氧化剂之间的预组织步骤中证明了电荷转移络合物(CTC)的形成。仅在中性溶剂(如二氯甲烷)中形成四氯化碳,其特征是强烈的着色。V 2 O 5将1,4-DHP芳构化在无溶剂介质中,乙酸在回流中的作用优于微波促进的反应。唯一合理的解释是在V 2 O 5的聚合物结构中发现的,该结构缓慢转移了活化反应物所需的微波能量。已发现4-正丙基-1,4-DHP的溶剂极性依赖性氧化脱烷基。出乎意料的是,与在相同反应条件下在二氯甲烷中获得的91%相比,在乙酸中的反应仅提供33%的脱烷基化产物。
This communication expresses aromatisation of 1,4-dihydropyridines to pyridine derivatives with the help of alumina supported benzimidazolium fluorochromate (BIFC) and quinolinium fluorochromate (QFC) as oxidants undersolvent-free microwave irradiation. Moderate to excellent yield (80-98%) of pyridine derivatives were achieved by this methodology.
An Efficient Transition-Metal-Chloride/Sodium-Nitrite/TEMPO Catalytic System for Aerobic Oxidative Aromatisation of Hantzsch 1,4-Dihydropyridines
作者:Bin-Hui Lou、Shu-Bin Chen、Jian Wang、Ying Chen、Jing-Hua Li
DOI:10.3184/174751913x13701832537930
日期:2013.7
A facile and efficient transition-metal-chloride/sodium-nitrite/TEMPO catalytic system for aerobic oxidative aromati-sation of Hantzsch 1,4-dihydropyridines in high yields under mild conditions is described.
Facile and efficient aromatization of 1,4-dihydropyridines with M(NO3)2·XH2O, TNCB, TBAP and HMTAI and preparation of deuterium labeled dehydronifedipine from nifedipine-d3
作者:Ajam C. Shaikh、Chinpiao Chen
DOI:10.1016/j.bmcl.2010.04.096
日期:2010.6
The easy and efficient aromatization of various 1,4-dihydropyridines was investigated using various metalnitrates, trinitratocerium(IV) bromate (TNCB), and tetrabutyl ammonium periodate (TBAP) as oxidant in acetic acid at 100 °C, as well as hexamethylenetetramine-iodine (HMTAI) reflux in methanol. The efficient conversion of nifedipine-d3 to dehydronifedipine-d3 as an internal standard can be used
在100°C的乙酸中,使用各种金属硝酸盐,溴化三硝酸铈(IV)溴酸盐(TNCB)和高碘酸四丁铵(TBAP)作为氧化剂,研究了各种1,4-二氢吡啶的简便有效芳构化。碘(HMTAI)在甲醇中回流。nifedipine-的有效转化d 3至dehydronifedipine- d 3作为内标可以以硝苯地平浓度的在体内测定中使用。
An efficient, metal-free, room temperature aromatization of Hantzsch-1,4-dihydropyridines with urea–hydrogen peroxide adduct, catalyzed by molecular iodine
A mild, highly efficient and metal-free synthetic method for aromatization of 1,4-dihydropyridines employing urea–hydrogen peroxide adduct as oxidant catalyzed by 20 mol % of molecular iodine was developed. The reaction was carried out in ethyl acetate at roomtemperature and the products were isolated in high to excellent yields. A plausible free-radical mechanism is proposed based on results obtained
A variety of Hantzschester1,4-dihydropyridines are efficiently oxidized to their corresponding pyridine compounds with iodineundernormalconditions and ultrasoundirradiation. The reactions were carried out in refluxing CH 3 CN.