4-吡唑基-2-芳氧基嘧啶类化合物的合成及除草活性

以2,4-二氯嘧啶为起始原料, 利用两个氯原子的活性差异, 经4-吡唑基-2-氯嘧啶合成了一系列4-吡唑基-2-芳氧基嘧啶类化合物, 通过¹H NMR和元素分析对所合成的化合物进行了结构表征. 初步生物活性测定结果表明, 所合成的化合物都表现出一定的除草活性. 当嘧啶环2位的氯原子被芳氧基取代后, 化合物的除草活性均有不同程度的提高, 例如5c和4a相比, 100 μg•mL^－1时化合物对油菜的抑制率由15.7%提高到85.4%, 对稗草的抑制率由原来的11.6%提高到84.0%.     

取代嘧啶化合物的合成和生物活性研究

合成了14个新型取代嘧啶类化合物,结构经质谱、红外光谱、氢核磁共振光谱和元素分析确证.杀虫、杀菌和除草活性测定结果表明,部分化合物具有良好的杀菌活性.在嘧啶环的2-位上导入二甲氨基时表现出杀菌活性,但在嘧啶环的5-位上有甲基取代基时,杀菌活性下降.在嘧啶的4-位导入苯氧基时,显示出良好的杀菌活性,如化合物3b,3c和3e,苯环上的最优取代基是2-硝基-4-三氟甲基.     

4, 6-二芳基-2-氨基嘧啶类衍生物的合成与生物活性

合成并表征了5种4,6-二芳基-2-氨基嘧啶类化合物。 测试了它们对大肠肝菌甲硫酰胺肽酶(EcMetAP)的抑制作用及对CXCR4受体的拮抗作用。 发现5种化合物均对EcMetAP酶活有抑制作用,除化合物2外均对CXCR4受体有拮抗作用。 利用FieldTemplater和FieldAlign软件对化合物1～5的上述活性构效关系进行了分析,初步认为化合物的嘧啶环3位N原子及4位取代苯环上若引入给电子基团,可增强这类化合物的EcMetAP酶抑制活性;在嘧啶环2位引入负电性较强的基团取代,改造2个苯环和嘧啶环的4、5、6位Ｃ原子的结构可增强其CXCR4受体拮抗活性。     

2-苯甲酰基嘧啶类化合物的合成与生物活性

2-嘧啶氧基-N-芳基苄胺类化合物结构经过两次骨架结构优化后得到2-苯甲酰基嘧啶类化合物二次先导结构.在二次先导结构基础上,共设计并合成了36个化合物,所有化合物结构经1H NMR、13C NMR、HRMS确认,并进行了室内杀菌活性筛选,对各部位取代基进行了逐次优化.结果表明2-苯甲酰基嘧啶类化合物中R1取代基以2位卤素或烷基取代的苯环或杂环活性最好;中间苯环6位引入氟原子活性保持;嘧啶环4,6位甲氧基取代活性较好,5位甲基取代活性大大降低;羰基被还原为羟基后活性消失.其中2,3-二氯-N-[2-(4,6-二甲氧基嘧啶-2-甲酰基)苯氧基]-N-甲基苯甲酰胺(4AHl)、2,5-二氯-N-[2-(4,6-二甲氧基嘧啶-2-甲酰基)苯氧基]-N-甲基苯甲酰胺(4AHn)及N-[2-(4,6-二甲氧基嘧啶-2-甲酰基)-3-氟苯氧基]-N,2-二甲基苯甲酰胺(4AFd)对黄瓜白粉病的杀菌活性与对照样苯菌酮相当.     

钯-碳/NaHCO3催化下2,4-二氯嘧啶的区域选择性脱氯反应：一种合成2-氯嘧啶的有效方法

本文报道了一种合成2-氯嘧啶的有效方法。易得原料2,4-二氯嘧啶在钯-碳/NaHCO3作用下可以区域选择性地脱除2位氯原子得到2-氯嘧啶。2-氯嘧啶可以用作多种复杂嘧啶衍生物的有效合成砌块。     

新型2-芳氨基嘧啶衍生物的合成

通过间羟基苯硼酸与2,4-二氯嘧啶的Suzuki反应及其后酚羟基的烷基化得到4-芳基-2-氯嘧啶衍生物. 然后, 采用Pd(PPh3)4/dppf催化剂, 在温和的条件下实现了4-芳基-2-氯嘧啶类化合物和芳香胺的偶联. 合成了3个结构新颖的2-芳氨基嘧啶类化合物. 中间体及产物的结构均经由IR, 1H NMR, 13C NMR, MS和元素分析表征而予以证实.     

N-[2-(4,6-二甲氧基嘧啶-2-氧基)苯亚甲基]-2-芳氧乙酰腙的合成与除草活性

通过2-(4,6-二甲氧基嘧啶-2-氧基)苯甲醛(1)与芳氧乙酰肼2的缩合反应,合成了10个含嘧啶结构的芳氧乙酰腙化合物3,其结构经1H NMR、IR、EI-MS或ESI-MS和元素分析测试技术确证。 除草活性测试(活体盆栽)结果表明,大部分目标化合物在1.5 kg/hm2浓度下, 无论苗前或苗后处理对苋菜均显示出很强抑制活性,化合物3e和3h的抑制率分别为100%和97.7%,而化合物3a、3b、3d、3e、3f和3h苗后处理对苋菜的抑制率均超过97%,对马唐的除草活性最差。 苯环4-位取代基性质对除草活性有规律性影响。     

噻唑啉-2-硫酮衍生物的合成与生物活性

根据活性亚结构拼接原理,将3-芳基-4-氨基-5-乙氧羰基(氰基)-3H-噻唑啉-2-硫酮与酰氯反应得到目标化合物3-芳基-4-取代苯氧乙酰氨基-5-乙氧羰基(氰基)-3H-噻唑啉-2-硫酮.再以3-苯基-4-氨基-5-乙氧羰基-3H-噻唑啉-2-硫酮为合成原料,经过Aza-Wittig反应得到目标化合物5-芳氧基-3,6-二芳基-2-硫代噻唑并[4,5-d]嘧啶-7-酮.通过IR,1H NMR,EI-MS,元素分析等方法对所合成的化合物进行了结构表征.代表化合物5-对氯苯氧基-3,6-二苯基-2-硫代-2,3-二氢噻唑并[4,5-d]嘧啶-7(6H)-酮(C1)经单晶X衍射证实了结构.除草活性测试结果表明:部分噻唑啉-2-酮类衍生物对稗草和油菜都表现出了较好的抑制活性.     

嘧啶酮衍生物的微波合成

在微波辅助下,Baylis-Hillman加成物与4-氨基-6-氯嘧啶或2-氨基-噻唑反应,快速合成了两类嘧啶酮衍生物——3-取代-7-氯-4H-嘧啶[1,2-b]哒嗪-4-酮和6-取代-5H-噻唑[3,2-a]嘧啶-5-酮,收率81%～98%,其结构经1H NMR,13C NMR,IR和MS确证。     

新型1, 6-二取代-5,6-二氢吡咯并[1,2-f]蝶啶衍生物的合成

以Pictet-Spengler型反应为基础, 设计了一条简便的合成1,6-二取代-5,6-二氢吡咯并[1,2-f]蝶啶衍生物的方法. 以4,6-二氯-5-氨基嘧啶为起始原料, 经Clauson-Kaas反应、胺亲核取代两步反应合成了4-氨基-6-氯-5-(1H-吡咯-1-基)-嘧啶, 然后与醛或脂肪酮在对甲苯磺酸催化下, 发生亲电关环得到1-氯-5,6-二氢-6-取代吡咯并[1,2-f]蝶啶, 其1位氯原子具有较高的反应活性, 易于被胺类亲核试剂取代.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.