Facile Synthesis of 6β-Hydroxy-7α(H)-eudesma-4-en-3-one and β-Cyperone

Eudesmane derivatives have been drawing considerable attention due to their wide spectrum of biological proerties, particulaly antifeedant, cell growth inhibitory and plant growth regulating activities.¹ In recent years a number of C-6 oxyfunctionalized eudesmanes and β-dihydroagarofurans,such as compounds 3-6,have been isolated from nature sources. However the reports on the synthesis of this particular kind of compounds are few and the reported syntheses are generally by synthetic methodology starting from α-santonin 2². Our interest of study on the synthesis of this kind of compounds prompted us to investigate a new synthetic route from cheap material (+)-dihydrocarvone 7.     

The First Efficient Approach from α-(-)-Santonin to Dihydroagarofuran Sesquiterpene

The naturally occurring dihydroagarofuran compounds have been demonstrated to show some important bioactive activities, such as insect antifeedant, antitumor activities.¹ Synthetic research of this kind of compounds have been attracting the increasing interest of organic chemists. Because a total synthesis of polyol skeleton involved too many steps,² our synthetic efforts are focusing on search for a short and efficient approach and thus, we begin with readily available α-(-)-santonin(1). The creative key steps include generation of C₅-OH, the stereochemical reversion at C-7 and the cyclization of tetrahydrofuran. A successful approach is shown in the following scheme.     

Synthesis,Chemistry and Applications of Heterocyclic Cage Compounds (V)

The synthesis and chemistry of polycyclic cage compounds have attracted considerable attention in recent years.¹ The vast majority of the work reported in this area has dealt with caybocyclic cage compounds. On the other hand, the synthesis and chemistry of heterocyclic cage compounds have received less attention. Recently, we have accomplished the synthesis of a series of oxa-cage compounds and performed the chemical transformations of these oxa-cage compounds.² As part of a program that involves the synthesis,chemistry and applications of heterocyclic cage compounds we report here the synthesis of heterocyclic cage compounds 1-12. We also wish to report the applications of compounds 7-12 on the π-facial selectivities. Studies on the cation-binding properties of compounds 1 and 2 and other oxa-cages are undertaken.     

Theoretical Studies of β-Peptide Models

Recently, the β-peptides, which consist entirely of β-amino acids instead of α-amino acids, have received intensive attention because of their interesting secondary structures.^1-3 Depending upon side chain substitution pattern, β-sheets, 14-helices, and 12-helices all have been observed.¹ Due to great variety of substitution patterns,the easiness of formation of secondary structures with even 4-6 residues compared to about 15 for natural peptides,and ready formation of cyclic compounds that stack into tube structures,⁴ β-peptides have generated great excitement. In addition,β-amino acids also frequently occur in natural products, especially cyclic peptides. It has been found that β-amino acids have excellent stability toward proteases. Therefore, they have wide applications in drug development.⁶     

微管菌素类似物的合成及抗肿瘤活性

以微管菌素为先导化合物, 设计合成了一系列类似物; 所有化合物的结构均经¹H NMR, ¹³C NMR及HRMS确证, 均为新化合物. 采用噻唑蓝(MTT)法对其抗肿瘤活性进行了初步筛选, 结果表明, 化合物Ⅱb具有一定的抗肿瘤活性.     

芳香寡聚磺酸酯桥联大环化合物的合成和紫外光谱

以芳香二磺酰氯和芳香二酚为原料,三乙胺作缚酸剂,二氯甲烷作溶剂,采取一步成环法合成了一系列新型的、芳环单元不同的芳香寡聚磺酸酯桥联大环化合物。 合成产物的结构用IR、¹H NMR、¹³C NMR和MALDI-TOF等技术手段进行了确认。 并对合成方法、紫外光谱和变温核磁结构研究进行了有价值的探讨。 化合物3~5的DMF溶液的最大紫外吸收峰在266 nm处,化合物6在267 nm处,摩尔吸光系数分别是4.65×10⁴、5.61×10⁴、5.09×10⁴和9.98×10⁴ L/(mol·cm);检出限分别是2.15×10^-7、1.78×10^-7、1.96×10^-7和1.00×10^-7 mol/L。 变温核磁数据证明,苯环上连有支链有利于固定构象,可以通过这种方法合成结构固定的杯芳烃。     

The Synthesis of 1,3-Dithiole Derivatives by Using Bun3P·CS2 Adduct

The red crystalline adducts formed between trialkylphosphines and carbon disulfide were confirmed to be l,3-dipolar structure by X-ray diffraction in 1961.^[1] Despite the apparent synthetic potential of the 1,3-dipolar structure, studies on its cycloaddition have only been restricted in electron-deficient alkynes as dipolarophiles.^[2-5] However, reactions with electron-rich alkynes have received little attention.     

First Total Synthesis of (±)-Ponganone Ⅲ

In recent years, the synthesis and pharmacology of pyranoflavanoids have been extensively investigated due to their wide range of pharmacological properties^[1-3]. Ponganone Ⅲ^[4],a new natural pyranoflavanone isolated from the Pongamia pinnala, was identified as (2S)-3',4'-dimethoxy-6',6"-dimethylpyrano-[2",3":7,8]-flavanone (2) on the basis of spectra data. Its precursor,3,4-dimethoxy-2'-hydroxy-6",6"-dimethylchromeno-[2",3":4',3']-chalcone (1) is also a new natural product^[5] isolated from the roots of Lonchocarpus subglaucescent. Their total synthesis have not been reported. Herein, we wish to report the first total synthesis of compounds 1 and 2 in order to confirm the proposed structure and further more to evaluate its biological activities.     

Synthesis of 6-aryl-3-cinchophenyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles

In recent years, fused heterocycles have been found to possess many unique properties in synthesis and pharmacology. Especially, 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles derivatives have been attracting much attention of chemists and pharmacologists because of their broad-spectrum biological activities such as antibacterial¹, hypotensive and CNS depressant² activities. We have prepared some 3,6-substituted 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and found that these compounds exhibited antimacrobial, insecticidal and promote plant growth.^3-5 Cinchophen had been used widely as medicine in clinic,but has been obsolete in recent years due to its by-effect. In order to seek for other uses of cinchophen, as a continuation of our preceeding studies, we used cinchophen as the starting material to synthesize ten new 6-aryl-3-cinchophenyl-l,2,4-triazolo[3,4-b]-l,3,4-thiadiazoles 5a-j. Compound 1 was prepared by the reaction of cinchophen and ethanol in the presence of sulfuric acid. 1 then reacted with hydrazine hydrate in absolute ethanol to give 2 which yielded 3 on treatment with CS₂ and KOH. On refluxing of 3 with excess hydrazine hydrate, 4 was obtained. 4 reacted with various substituted benzoic acids in the presence of POCl₃ to afifort 5a-j.     

Convenient Synthetic Route to (±)-Frontaliu

Frontalin, the pheromone of Dendroctonus Bark Beetles, was first isolated by Kinzer^[1] from hindgut extracts of male western pine beetles. Its structure was determined as 1,5-dimethyl-6,8-dioxabicyclo[3.2.1] octane (1) by spectral analysis and was confirmed by the synthesis of its racemate^[1,2]. On account of its structural novelty and economic value, this compound has been studied extensively ^[3-5]. But most of its synthetic methods required relatively longer steps or suffered from the inaccessibility of starting materials or reagents. Now, we report a convenient synthetic method for (±)-frontalin starting from easily available material, natural unsaturated aliphatic aicd, oleic acid. The synthesis is shown in scheme.     

Photochemical Synthesis of Cyclopentadienyl-hexamethylbenzene-iron Tetrafluoborate

As a new type of photoinitiator, cyclopentadienyl-aryl-iron tetrafluoroborate has received much attention^[1]. We^[2] have improved the synthesis method of cyclopen-tadienyl-benzene-iron tetrafluoroborate reported by the literature^[3,4]. This synthetic method is to reflex the mixture of ferrocene and fluid aromatic compound; the cyclopentadiene of ferrocene was replaced by the incoming aromatic compound. However, this method is rather limited if the ligands are solid aromatic compounds.     

A Catalytic Enantioselective Synthesis of Biologically Interesting Cyclopropane Amines

The synthesis of cyclopropane amine has attracted considerable interest from organic chemists because of the biologically importance and its occurrence in numerous natural products¹. Several synthetic cyclopropane amines have been used as drugs, e.g. the monoamine oxidase inhibitor tranylcypromine (1)². However, it has been found that two enantiomers of chiral cyclopropane amine have different pharmacological effects³,which demands organic chemists to develop efficient methods to prepare them enantioselectively. Previous synthesis of enantiomerically pure cyclopropane amines involves resolution of racemic cyclopropane carboxylic acid followed by Curtius degradation⁴.     

AN EFFICIENT SYNTHESIS OF ALIPHATIC α-ORGANOTHIO ALDOXIME

The importance of the aliphatic α-organothio aldoxime compound 3 in the preparation of various pesticides is well established. Molecules comprising the α-organothio oxime moiety have been reported to exhibit insecticidal,nematocidal,miticidal activities.^[1-2] In the synthesis of the compound 3,the chlorination of the corresponding aliphatic aldoxime 1 is the key step.In conventional methods, the aliphatic aldoxime 1 is chlorinated by chlorine,then the resulting hydroxime acid chloride 2 is treated with sodium alkyl mercaptide to obtain the desired compounds 3^[3]. Although free Cl₂ is the most common chlorinating agent,it is laborious to determine the accurate amount that has been absorbed,and the high reactivity of Cl₂ always leads to side reactions. In connection with an our ongoing research project, we require an efficient and simple method for the synthesis of the compound 3.An improved synthesis process according to the following scheme is reported in this paper.     

The Synthesis of Novel ALS Inhibitors N-(Substituted Benzyl Alkoxyl Phosphonyl)-N'-(4,6-Disubstituted Pyrimidin-2-yl) Ureas

Sulfonylurea herbicides are a new class of herbicides discovered in the mid-1970's^[1],whose mode of action has been established as the inhibition of ALS (acetolactate synthase)^[2]. Much attention has been focused on this kind of compound, since they have unprecedented use rates,a high degree of selectivity, and excellent environmental safety. Numerous modifications of the structure of this class of herbicides have been reported.     

Spiral Cyclization of a-Carbonyl Radicals

α-Carbonyl radicals cyclization reactions have been applied successfully toward total synthesis of several natural products,such as modhephene,¹ (-)-dendrobine,² and (-)-5-oxosiphiperfol-6-ene.³     

Synthesis of 6-(1-Aryl-5-methyl-1,2,3-triazol-4-yl)-3-(4-Pyridyl)-s-Triazolo[3,4-b]-l,3,4-Thiadiazoles

A survey of literature¹ revealed that s-triazolo[3,4-b]-1,3,4-thiadiazole, an interesting fused system of s-triazole and 1,3,4-thiadiazole rings, has received much attention during recent years on account of its prominent utilizations as antifungal, antiinflammatory, antiviral, analgesic and anthelmintic agents probably resulting from its planner and compact structure. Our earlier work on the synthesis of this class of heterocycles showed antibacterial, herbicidal and plant growth regulative properties^2-3 for the compounds. 1,2,3-Triazole derivatives have found their wide use in medicine, agriculture and industry^4-5. Incorporation of 1,2,3-triazole moiety into the 6-position of this ring system may lead to achieving compounds of better biological activities. In view of the above findings coupled with scanty reports on these condensed compounds carrying 6-heterocyclic groups, we wish to report here the condensation of 4-amino-5-mercapto-3-(4-pyridyl)-l,2,4-triazole(2) with 1-aryl-4-carboxy-5-methyl-1,2,3-triazoles(1_a-j) as a part of our continuing interest in this area.     

对称吡啶基二噻吩乙烯光致变色化合物的合成与性能

二噻吩乙烯光致变色化合物具有热稳定性高、抗疲劳性好等优点。 本文以2-甲基噻吩为原料,经过Suzuki偶联、傅克酰基化、McMurry环合3步反应制备1,2-二(5-吡啶基-2-甲基噻吩-3-基)环戊烯,总收率61%。 所有中间体及目标产物均已通过核磁共振、质谱、红外光谱等技术手段表征。 该合成方法具有合成步骤少、简便、总收率高、易于工业化生产等优点。 利用紫外-可见吸收光谱、荧光光谱对该化合物及其与镍离子、锡离子相互作用的光致变色性能以及应用进行了研究。 对称吡啶基二噻吩乙烯通过与金属配位在紫外光的照射前后显示出不同的颜色和光谱吸收,可以用作新型金属离子探针。     

Studies on Bioactive Selenium-containing Organophosphorus Compounds: Synthesis of 1-Aminoalkanephosphonate Derivatives of Benzisoselenazolone and Their Antitumor Activity

Various selenium-containing compounds are widely used as reagents and intermediates in organic synthesis.¹ In recent years biologically active organoselenium compounds have begun to attract considerable interest due to their unique and diverse potential pharmacological importance such as broad spectrum antitumor and antiviral activities, and some of them are even many times more active than their thio analogues.^2,3 It was found that benzisoselenazolones[e.g.,Ebselen, 2-phenyl-1,2-benzisoselenazol-3(2H)-one], are effective for the treatment of diseases caused by cell damage owing to increased formation of active oxygen metabolites⁴ and these pharmacological effects are mainly attributed to the glutathione peroxidase (GSH-Px) like properties.⁵     

First Total Synthesis of 4,5-Secoeudesmane-type and Iphionane-type Compounds——Synthesis of 4,5-Dioxo-seco-γ-eudesmol and 5β,11-Dihydroxyiphionan-4-one

4,5-Secoeudesmane-type and iphionane-type compounds are sesquiterpenes with new carbon skeletons found in natrual sources in recent years.^1-6 The Co-occurence of 4,5-secoeudesmanes, iphionanes and eudesmanes as natrual products suggests that 4,5-secoeudesmanes, iphionanes most likely are generated biogenetically from eudesmanes, and iphionanes are formed biogenetically by aldol reaction of 4,5-dioxosecoeudesmanes.^1,4,6,7 The study on the synthesis of this two kind of new sesquiterpenes has not been reported in the literature.     

Design,Synthesis and Herbicidal Activity of Novel Sulfonylureas Containing Tetrahydrophthalimide Substructure

To develop novel sulfonylurea herbicides, a series of chlorsulfuron derivatives was designed and synthesized through introducing tetrahydrophthalimide substructure taken from protoporphyrinogen IX oxidase(PPO) inhibitors onto the critical 5-position of the classical benzene ring. The structures of title compounds were confirmed by infrared spectroscopy, ultraviolet spectroscopy, ¹H and ¹³C NMR spectrometry, mass spectrometry and elemental analysis. In addition, the crystal structure of compound II-5 was further determined by X-ray diffraction analysis. Bioassay results showed that individual compounds exhibited good herbicidal activities, especially compound II-8, which displayed 100% inhibition rate against Echinochloa crusgalli at 150 g/ha(1 ha=10⁴ m²) with the method of foliage spray in the pot experiment.