3-芳氧基-6-取代哒嗪的合成及其除草活性

合成了系列3-芳氧基-6-取代哒嗪类化合物.化合物结构经¹HNMR、元素分析、IR和MS确证.生物活性测试结果表明,该类化合物具有很好的除草活性,讨论了其结构与除草活性的关系.     

卤代哒嗪酮氟代反应的研究

前文^[1,2]报道了氟代哒嗪二酮化合物的合成及生理活性,其合成路线较长,收率较低。     

3-取代苄氧基-6-取代氨基哒嗪衍生物的合成及其除草活性

通过3-取代苄氧基-6-氟哒嗪在75～80 ℃与二甲胺的绝对无水乙醇溶液封管反应, 或在回流条件下分别与吗啡啉或哌啶反应, 合成一系列新颖的3-取代苄氧基-6-取代氨基哒嗪类化合物, 它们的结构均经IR, ¹H NMR和元素分析确证. 初步的除草活性测定结果表明, 该类化合物具有一定的除草活性, 讨论了它们的结构与除草活性的关系.     

硫原子上亲核取代反应的密度泛函理论研究

在B3LYP/6-311 G(2df,p)的水平上,对反应X- CH3SCl(X=F,Cl,Br,I)进行了理论研究.计算结果表明:X-(X=Cl,Br,I)与CH3SCl作用时,实际发生的是在硫原子上而不是在碳原子上的亲核取代反应,而且属于加成-消去机理.但是F-与CH3SCl作用则容易发生脱质子反应.     

1－取代苯基－1，4－二氢－6－甲基－4－哒嗪酮－3－酰肼衍生物的合成及生物活性

以1－取代苯基－3－羰基肼－1，4－二氢－6－甲基－4－哒嗪酮为原料，进行 衍生化，合成了哒嗪酮的酰腙、酰氨基取代脲、N－乙氧基羰基羰基肼、N－氯乙酰 基羰基肼等五类新型化合物，并研究其生物活性。初步生物活性测试表明目标化合 物对烟草花叶病毒（TMV）、水稻纹枯病（Pellcularia sasakki)和小麦锈病（ Puccinia recondita tritici)具有一定的抑制作用。其结构经元素分析、红外光 谱及^1H NMR确证。     

3-芳基-5-巯基-1,2,4-三唑的亲核取代反应研究

以3-芳基-5-巯基-1,2,4-三唑为原料合成了20个3-芳基-1,2,4-三唑-5-巯基乙酸乙酯(2a～e)、3-芳基-1,2,4-三唑-5-巯基乙酸(3a～e)、3-芳基-5,6-二氢噻唑并[2,3-c]均三唑(5a～e)和3-芳基-6,7-二氢均三唑并[3,4-b][1,3]噻嗪(6a～e)。研究了3a～e在微波辐射下的环化反应，合成了5个3-芳基-5-氧代-6H-噻唑[2,3-c]均三唑(4a～e)。产物经元素分析、红外、核磁共振以及质谱方法确定了结构。初步研究了代表化合物的生物活性。     

6－S－（取代的三或四唑杂环基）－1，2：3，4－二－O－异亚丙基－α-D吡喃型半乳糖的合成研究

报道了6－O－对甲苯磺酰基－1，2：3，4－二－O－异亚丙基－α-D吡喃型半 乳糖（3）与取代的3－巯基三唑或5－巯基四唑4a-4c或5a-5f的亲核取代反应，合 成了9个6－S－（取代的三或四唑杂环基）－1，2：3，4－二－O－异亚丙基－α- D吡喃型半乳糖（6a-6i），通过元素分析，IR，NMR和MS确证了上述化合物的结构 ，并经分子模型计算进行了其构象分析。     

3-(未)取代苄氧基-6-氟哒嗪的合成及其除草活性

通过3,6-二氟哒嗪与(未)取代苄醇在NaOH/CH₃CN体系反应, 合成了一系列未见报道的3-(未)取代苄氧基-6-氟哒嗪, 其结构均经¹H NMR, IR和元素分析确证. 初步的生物活性测试结果表明, 所合成的化合物对油菜和稗草均有一定的抑制作用, 讨论了其结构与除草活性的关系.     

3-取代苄氧基-6-(取代-1H-吡唑-1-基)哒嗪的合成与生物活性

3-氯-6-肼基哒嗪分别与乙酰丙酮和3-二甲胺基丙烯醛反应, 合成了中间体3-氯-6-(3,5-二甲基-1H-吡唑-1-基)哒嗪(2)和3-氯-6-(1H-吡唑-1-基)哒嗪(4), 它们与多种取代苄醇反应, 得到了一系列未见报道的3-取代苄氧基-6-(取代-1H-吡唑-1-基)哒嗪, 其结构均经1H NMR, IR和元素分析确证. 初步的生物活性测试结果表明, 所合成的化合物对油菜和稗草均具有一定的抑制作用.     

取代二苯醚的新合成反应及历程研究

在碱金属亚硝酸盐和碳酸盐存在下, 被强引电子基团取代的硝基苯在非质子极性溶剂中能发生自射缩合反应, 生成结构对称的双取代二苯醚, 收率较高。此类反应的主要历程属于SNAr, 但同时也存在着SRNAr(SET)历程作为次要途径。     

PEG 400 promoted nucleophilic substitution reaction of halides into organic azides under mild conditions

Abstract

Polyethylene glycol 400 (PEG 400) has been demonstrated as an efficient and eco-friendly reaction medium for the preparation of organic azides from structurally diverse halides by nucleophilic substitution reaction with NaN₃ under mild conditions. The advantages of this protocol are: operational simplicity, environmental safety, broad substrate scope, excellent functional group tolerance, and short reaction time. The PEG 400 can be recovered and reused.     

双取代哒嗪有机液晶的合成、结构及刚性实对介晶性的影响

合成了16个中心桥连基为哒嗪环、酯基或CH=N基,含有苯环、不同刚性实长度和不同末端链长的哒嗪化合物,并通过DSC对其介晶进行了表征。研究表明,末端链长度对相变温度和清亮点温度均有影响,但对相变温度范围影响较小,而刚性实长度对其影响却较大。     

A new method for the synthesis of 3-aryl-6-(2-pyrrolyl)pyridazines

A new method for the synthesis of 3-halo-6-(N-tosyl-2-pyrrolyl)pyridazine 7 was developed. Suzuki cross-coupling reactions of 7 with arylboronic acids and in situ de-tosylation gave a variety of novel 3-aryl-6-(2-pyrrolyl)pyridazines. It found that protection of the pyrrolyl moiety was necessary for efficient coupling reaction.     

Study on the synthesis of 6-alkylaminouridines via the nucleophilic aromatic substitution reaction of 6-cyanouridine derivatives

6-Cyanouracil derivatives underwent direct substitution reactions with selective primary amines in the presence of N,N-dimethylaminopyridine as a catalyst to give the corresponding 6-alkylaminouracils. This reaction provides a facile access to versatile 6-alkylaminouridine derivatives.     

Multicomponent reaction of amine,carbon disulfide,and fluoronitrobenzene via nucleophilic attack on the fluorinated carbon for the synthesis of nitrophenyl methylcarbamodithioates

In this paper, multicomponent reaction of amine, carbon disulfide and fluoronitrobenzene is reported for the synthesis of nitrophenyl methylcarbamodithioate derivatives. The method is based on the nucleophilic attack of the activated methylcarbamodithioate salt to fluoronitrobenzene. Several starting materials are tested and successfully produced the corresponding nitrophenyl methylcarbamodithioate. A possible mechanism for the reaction is suggested.     

New synthetic method of 1,2-diaryl-1,2-dicarba-closo-dodecaboranes employing aromatic nucleophilic substitution (SNAr) reaction

Aromatic nucleophilic substitution (S_NAr) reaction of 1-phenyl-o-carborane with 4-nitrofluorobenzene in the presence of NaH or KO^tBu proceeded smoothly to give 1-(4-nitrophenyl)-2-phenyl-o-carborane; similar reaction affords various 1,2-diaryl-o-carboranes, which are useful precursors for macromolecular construction and drug design.     

A simple and efficient approach for the synthesis of a novel class aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives via intramolecular nucleophilic substitution reaction

In this study, we synthesized a new series of substituted aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives (6-24) in yields ranging from 42 to 70% with an interesting mechanism that involves internal nucleophilic substitution followed by an S_N2-type nucleophilic substitution. First, 1-(4-chlorophenyl)-2-((5-methyl-1,3,4-thiadiazol-2-yl)thio)ethanone (3) was synthesized from the reaction of 5-methyl-1,3,4-thiadiazole-2-thiol (1) with 2-bromo-1-(4-chlorophenyl)ethanone (2) in the presence of potassium hydroxide. Then, 1-(4-chlorophenyl)-2-((5-methyl-1,3,4-thiadiazol-2-yl)thio)ethanol (4) was synthesized by a reduction reaction of this compound using NaBH₄. Finally, 5-methyl-3-alkyl-1,3,4-thiadiazol-2(3H)-one derivatives (6-24), which are the target compounds, were synthesized from the reaction of this compound (4), which is a secondary alcohol with various alkyl halides (5a-n) in the presence of sodium hydride (NaH). This study presents an interesting reaction mechanism related to the synthesis of aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives that is not recorded in the literature.     

Alkali-metal-ion catalysis and inhibition in the nucleophilic displacement reaction of y-substituted phenyl diphenylphosphinates and diphenylphosphinothioates with alkali-metal ethoxides: effect of changing the electrophilic center from P=O to P=S

A kinetic study of the nucleophilic substitution reaction of Y‐substituted phenyl diphenylphosphinothioates 2 a – g with alkali‐metal ethoxides (MOEt; M=Li, Na, K) in anhydrous ethanol at (25.0±0.1) °C is reported. Plots of pseudo‐first‐order rate constants (k_obsd) versus [MOEt], the alkali ethoxide concentration, show distinct upward (KOEt) and downward (LiOEt) curvatures, respectively, pointing to the importance of ion‐pairing phenomena and a differential reactivity of dissociated EtO^? and ion‐paired MOEt. Based on ion‐pairing treatment of the kinetic data, the k_obsd values were dissected into k and k_MOEt, the second‐order rate constants for the reaction with the dissociated EtO^? and ion‐paired MOEt, respectively. The reactivity of MOEt toward 2 b (Y=4‐NO₂) increases in the order LiOEt?NaOEt>KOEt>EtO^?. The current study based on Yukawa–Tsuno analysis has revealed that the reactions of 2 a – g (P?S) and Y‐substituted phenyl diphenylphosphinates 1 a – g (P?O) with MOEt proceed through the same concerted mechanism, which indicates that the contrasting selectivity patterns are not due to a difference in reaction mechanism. The P?O compounds 1 a – g are approximately 80‐fold more reactive than the P?S compounds 2 a – g toward the dissociated EtO^? (regardless of the electronic nature of substituent Y) but are up to 3.1×10³‐fold more reactive toward ion‐paired LiOEt. The origin of the contrasting selectivity patterns is further discussed on the basis of competing electrostatic effects and solvational requirements as a function of anionic electric field strength and cation size (Eisenman’s theory).