3-取代和3,4-二取代噻吩的合成与表征

以噻吩、48% (m/m)氢溴酸水溶液、35% (m/m)过氧化氢水溶液、高纯氨、金属钠为原料合成了3-溴噻吩和3,4-二溴噻吩,3-溴噻吩和3,4-二溴噻吩分别以(dppp)NiCl2为催化剂合成了3-烷基噻吩和3,4-二烷基噻吩.3-溴噻吩以CuI, NaHSO4为催化剂合成了3-烷氧基噻吩,产率较高.并用核磁共振谱、质谱和元素分析方法进行了表征.     

烷基噻吩在MoS2团簇上吸附行为的密度泛函理论研究

运用密度泛函理论(DFT),采用Mo16S32团簇模型,在PW91/DNP水平上研究了噻吩(TP)及一系列烷基噻吩类硫化物如2-甲基噻吩(2-MT)、3-甲基噻吩(3-MT)、2,3-二甲基噻吩(2,3-DMT)、2,4-二甲基噻吩(2,4-DMT)、2,5-二甲基噻吩(2,5-DMT)及3,4-二甲基噻吩(3,4-DMT)等在加氢脱硫催化剂MoS2上的吸附行为.结果表明,在η1S吸附构型中,Mo16S32团簇对烷基噻吩吸附能力的顺序为2,5-DMT>2,4-DMT≈2,3-DMT>2-MT>3,4-DMT>3-MT>TP.通过键长、Mayer键级、Mulliken电荷分析可知,当噻吩环的2-或5-位不含甲基时,吸附能随硫原子电荷密度的增加而增大;2-或5-位含甲基时,甲基与团簇上相邻的Mo原子发生了弱的相互作用,使吸附能增大;虽然2,5-DMT的2-和5-位均含有甲基,但甲基离团簇上相邻的Mo较远,相互作用较小,吸附能较2,3-DMT和2,4-DMT增加的较少.文中还对各硫化物在MoS2催化剂上的加氢脱硫反应进行了讨论.     

羟甲基和碘甲基取代的3,4-亚乙基二氧噻吩衍生物及其选择性酯化与醚化

羟甲基或碘甲基取代的3,4-亚乙基二氧噻吩(EDOT)衍生物与含氰乙基或羧酸基的四硫代富瓦烯(TTF)衍生物通过酯化或醚化反应可生成EDOT-TTF类型的化合物.在此过程中发现,由3,4-二羟基噻吩-2,5-二羧酸甲酯(1)与环氧溴丙烷经醚化反应生成的关环产物是一个由3,4-二氧-羟甲基乙基噻吩-2,5-二羧酸甲酯(2)与3,4-二氧-2’-羟基亚丙基噻吩-2,5-二羧酸甲酯(2’)组成的混合物,两者很难用常规手段分离.由(2+2’)衍生的2,5-二羧酸甲酯-3,4-二氧-碘代甲基亚乙基噻吩(3)和3,4-二氧-碘代亚丙基噻吩-2,5-二羧酸甲酯(3’)以及3,4-二氧-羟甲基亚乙基噻吩(4)与3,4-二氧-2’-羟基亚丙基噻吩(4’)与2-氰乙基硫-3-甲基硫-6,7-二(正己基硫)-四硫代富瓦烯(TTF-1)或2-羧甲基硫-3-甲基硫-6,7-二(正己基硫)-四硫代富瓦烯(TTF-3)进行醚化或酯化反应表现出了高度的选择性,只有3能与TTF-1反应生成结构单一的EDOT-TTF 1.同样只有4能与TTF-3反应生成结构单一的EDOT-TTF 2.     

5-烷氧基-3,4-二卤-2(5H)-呋喃酮与脂肪胺类的反应研究

在氟化钾作催化剂和四氢呋喃作溶剂的条件下,研究了系列脂肪胺亲核试剂与5-烷氧基-3,4-二卤-2(5H)-呋喃酮发生的反应,通过旋光度,UV-Vis,IR,1H NMR,13C NMR,MS,元素分析和X射线单晶衍射等表征方法对产物进行结构表征,发现通常情况下发生预期的串联迈克尔加成-消除反应,合成了13个新的β-胺基-2(5H)-呋喃酮.但是,空间位阻较大的二环己基胺与5-烷氧基-3,4-二卤-2(5H)-呋喃酮反应时,却得到了4个异常的2(5H)-呋喃酮开环产物,其可能是经开环重排反应的机理得到的.     

d-生物素的不对称全合成研究(Ⅴ)

以二异丁基氢化铝使(3aS,6aR)-1,3-二苄基-四氢-4H-噻吩并[3,4-d]-咪唑-2,4(1H)-二酮(1)高立体选择性地还原成(3aS,4S,6aR)-1,3-二苄基-4-羟基-四氢-1H-噻吩并[3,4-d]-咪唑-2(3H)-酮(2),再经缩合,Witting烯化成(3aS,6aR)-1,3-二苄基-四氢-1H-噻吩并[3,4-d]咪唑-2(3)-酮-4-烯戊酸(4),后者经催化氢转移还原、脱苄即得d-生物素,以化合物1计算总产率为42%.     

含五氟苯的噻吩并吡咯二酮苯并二噻吩共轭聚合物的合成及其性能

以3,4-噻吩二甲酸和五氟苯胺为起始原料,经酰化、缩合和NBS溴代反应制得2,5-二溴-5-五氟苯基噻吩［3,4-c］吡咯-4,6-二酮(2); 2经两步反应制得2-溴-2,5-二噻吩-5-五氟苯基噻吩［3,4-c］吡咯-4,6-二酮(4);以苯并二噻吩衍生物（BDT-1和BDT-2）为给体单元,2或4为受体单元,分别经Stille偶联缩聚反应合成了3个含五氟苯的噻吩并吡咯二酮-苯并二噻吩共轭共聚物(5a~5c),其结构和性能经¹H NMR, ¹³C NMR, UV-Vis, TGA和循环伏安法表征。结果表明：5a, 5b和5c的最大吸收峰分别位于559 nm, 559 nm和547 nm,光学带隙分别为1.70 eV, 1.73 eV, 1.68 eV(薄膜)和1.84 eV, 1.83 eV, 1.81 eV(甲苯);失重5%的温度为307～325 ℃; 5a~5c的起始氧化电位和起始还原电位分别为1.14 V, 1.18 V, 1.03 V和-0.67 V, -0.67 V, -0.70 V; HOMO和LUMO能级分别为-5.54 eV, -5.58 eV, -5.43 eV和-3.73 eV, -3.73 eV, -3.70 eV。     

一种低带隙平面分子结构的聚合物合成

合成了一种给-受体型平面分子结构的低带隙共轭聚合物QP-1(聚[2,6-4,8-双十二烷氧基苯并[1,2-b;3,4-b’]二噻吩-4,7-二[2,5-噻吩]-5,6-二烷氧基-2,1,3苯并噻二唑)),研究了其热学、光物理和光伏性质。由电化学测试得到聚合物的带隙为1.79eV,最高分子占有轨道HOMO和最低分子未占轨道LUMO值分别为-5.47 eV和-3.49 eV。与富勒烯的衍生物PCBM有较为理想的能级匹配水平。使用聚合物/PC71BM共混物作为活性层构筑了本体异质结聚合物太阳能电池。光伏电池的能量转换效率为1.01%,开路电压为0.58 V,短路电流为4.25 mA/cm2,填充因子ff值为0.33。X射线粉末衍射(XRD)结果显示平面主链间的距离为0.365nm,具有较好的结晶性。     

4-(甲氧基噻吩基)-3-(取代苯甲酰基)-吡咯类化合物的合成与抗肿瘤活性研究

分别以2-甲氧基噻吩、3-甲氧基噻吩、3,4-二溴噻吩和取代苯乙酮为原料,经过溴甲氧基取代反应、VilsmeierHack反应、羟醛缩合和Van Leusen吡咯合成法,设计并合成了33个未见文献报道的4-取代噻吩基吡咯类化合物.其结构均经~1H NMR,~(13)C NMR及HRMS确认,同时采用噻唑蓝(MTT)法测试了目标化合物对CHO、HCT-116、MGC80-3、SGC-7901以及HUVEC细胞增殖抑制活性.结果显示,部分化合对MGC80-3细胞有较强(IC_(50)≤20μml/L)或中等(20μmol/LIC_(50)≤50μmol/L)增殖抑制作用,其中[4-(3,4-二甲氧基噻吩-2-基)-1H-吡咯-3-基](4-苯基苯基)甲酮(4a-2)和[4-(3,4-二甲氧基噻吩-2-基)-1H-吡咯-3-基](3-溴苯基)甲酮(4a-7)的IC_(50)值分别为8.6和8.5μmol/L;化合物4a-7对HCT-116细胞有中等抑制活性;化合物4a-2和4a-7对SGC-7901细胞有中等增殖抑制活性;并且几乎所有化合物对正常人体细胞HUVEC无明显抑制作用.     

固相法制备D-A-D型共轭聚合物/MnO2复合物及光催化性能研究

分别采用固相法即固相化学法和固相物理共混法制备了给体-受体-给体(D-A-D)型共轭聚合物聚(2,5-二(2-(3,4-乙撑二氧噻吩))基哒嗪)与纳米MnO2的复合物(3,4-乙撑二氧噻吩环作为给体单元;哒嗪环作为受体单元),采用FT-IR、UV-vis、XRD、SEM等手段对复合物的结构和形貌进行了表征,并研究了该类...     

含联苯醚结构2(5H)-呋喃酮衍生物的合成

以硫酸为催化剂,不同4'-烷氧基-4-羟基联苯与粘卤酸在甲苯溶剂中回流,经脱水醚化反应合成了16个新型的5-(4'-烷氧基-4-联苯氧基)-3,4-二卤-2(5H)-呋喃酮化合物,产率30%~58%(大部分47%以上).中等产率可能与该酸催化的反应为SN2亲核取代反应有关.新化合物的结构经FTIR,UV,1H NMR,13C NMR和元素分析确证.这些具有不同生物活性基团化合物的设计与合成,为新型2(5H)-呋喃酮衍生物的合成,以及由不同羟基化合物合成芳香醚类化合物提供了参考.     

A Facile Synthesis of 3,4-Dialkoxythiophenes

Dialkylation of diethyl 3,4-dihydroxythiophenedicarboxylate followed by ester hydrolysis and acid decarboxylation provides a general route to 3,4-dialkoxythiophenes.     

Diprotodecarboxylation Reactions of 3,4-Dialkoxythiophene-2,5-dicarboxylic Acids Mediated by Ag2CO3 and Microwaves

An efficient and rapid method is reported to obtain 3,4-dialkoxythiophenes from 3,4-dialkoxythiophene-2,5-dicarboxylic acids through a diprotodecarboxylation reaction with Ag₂CO₃/AcOH as a catalytic system and microwave heating in dimethylsulfoxide (DMSO) as solvent. This methodology lets us obtain for the first time good performance with thiophenes bearing strong electron-donating groups such as alkoxides. This methodology eliminates the usage of harmful quinoline as solvent, as well as the long reaction times typically used (12–18 h) to obtain the 3,4-dialkoxythiophenes. The reaction of 7 diacids showed good yields (60–89%) following 20 min of microwave heating in a temperature range of 120–150 °C.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Facile synthesis of 4-substituted 3,4-dihydrocoumarins via an organocatalytic double decarboxylation process

3,4-Dihydrocoumarins, considered to be valuable building blocks, have attracted considerable attention due to their various biological activities. Herein, we have documented an efficient and convenient double decarboxylation process for the synthesis of 4-substituted 3,4-dihydrocoumarin in moderate to excellent yields under mild reaction conditions (up to 98%).     

An intermediate for the clean synthesis of ionic liquids: isolation and crystal structure of 1,3-dimethylimidazolium hydrogen carbonate monohydrate

1,3-Dimethylimidazolium-2-carboxylate and carbonic acid have been used to prepare a 1,3-dimethylimidazolium hydrogen carbonate salt by means of a Krapcho reaction. The ability to form hydrogen carbonate azolium salts allows for them to be used as precursors for fast, efficient, environmentally benign, and halide-free syntheses of many ionic liquids by a simple, acid-base reaction of virtually any acid (inorganic, organic, and organic noncarboxylic) with a pK(a) less than that of HCO(3) (-). Additionally, the kinetics of this reaction can be accelerated by employing catalytic amounts of DMSO (a traditional Krapcho solvent used in decarboxylation reactions) to catalyze the decarboxylation. The crystal structure of 1,3-dimethylimidazolium hydrogen carbonate monohydrate is the first example of an imidazolium-based hydrogen carbonate salt. There is a strong 2D hydrogen-bonded network with facially pi-stacked imidazolium cations located in the cavities created by this framework.     

New Synthesis of 3-Alkyl Coumarins

3-Alkyl coumarins are reported to have anthelmintic, hypnotic and insecticidal properties^1–3. Here we report a novel general method for the synthesis of 3-alkylated coumarins. This involves direct C-alkylatioa at the C-3 position of 3-carbethoxy-3,4-dihydrocoumarin followed by hydrolysis, decarboxylation and dehydrogenation of the resulting dihydrocoumarin. 3-Methyl-, 3-ethyl-, 3-n-pro-pyl-, and 3-benzylcoumarins have been synthesised in good yields following the same procedure depicted in the Scheme-1.     

Synthesis of 3,4-Bis (4′-Methylphenyl) Thieno [2,3-b]Thiophene: First Example of Peri-Diaryl Thienothiophene

3,4-bis(4′-methylphenyl) thienothiophene, the first example of peri-(3,4) diaryl thienothiophene has been synthesized by a sequence involving preparation of ketene dithioacetal, Dieckmann type cyclization, ester hydrolysis and decarboxylation.     

Remarkable synergism in methylimidazole-promoted decarboxylation of substituted cinnamic acid derivatives in basic water medium under microwave irradiation: a clean synthesis of hydroxylated (E)-stilbenes

A metal-free protocol for decarboxylation of substituted α-phenylcinnamic acid derivatives in aqueous media is developed, wherein a remarkable synergism between methylimidazole and aq NaHCO₃ in polyethylene glycol under microwave furnished the corresponding para/ortho hydroxylated (E)-stilbenes in a mild and efficient manner. The critical role of water in facilitating the decarboxylation imparts an interesting facet to the synthetic utility of water mediated organic transformations. The developed protocol provides a clean alternative to the hitherto indispensable multistep approaches involving toxic quinoline and a copper salt combination as the common decarboxylating agent.     

The influence of modified EK2010 catalyst to the decarboxylation of oleic acid

It is known that the zeolite type catalytic system is the main catalyst of decarboxylation process. However, the influence of modification of acid–base properties of this type of catalyst to the decarboxylation reaction of organic acids is not investigated widely. Therefore, the modification of the bifunctional “EK2010” catalyst with MgO is conducted in the submitted paper. The influence of this modification to the route of decarboxylation process of organic acids and yield of target products have been investigated in the example of oleic acid. It is found out that, when the basicity is increasing, the modification occurs on the surface of catalyst and the activity of the catalyst is rising and decarboxylation reaction of oleic acid is going very well. The catalysts was investigated with XRD, XRF, TGA and IR techniques.     

An unexpected oxidative decarboxylation reaction of 2,3-dihydroxybenzoic acid in the synthesis of new dibenzyltetrahydroquinoxalinediones

Chemical and electrochemical oxidation of different catechols were carried out in the presence of N,N′-dibenzylethylenediamine (DBEDA) in a phosphate buffer/acetonitrile solution for the synthesis of different new dibenzyltetrahydroquinoxalinedione derivatives. The oxidation of catechol (1a), 2,3-dihydroxybenzoic acid (1e), and 3,4-dihydroxybenzoic acid (1d) led to the same product, probably due to the decarboxylation reaction of intermediates. An oxidative decarboxylation reaction of 3,4-dihydroxybenzoic acid (1d) has been reported before, while an unexpected oxidative decarboxylation reaction of 2,3-dihydroxybenzoic acid (1e) in the presence of DBEDA is reported for the first time.     

Theoretical investigation of triphenylamine dye/titanium dioxide interface for dye-sensitized solar cells

The structural, electronic and optical features of two metal-free triphenylamine (TPA) organic dyes (namely C206 and C217) before and after binding to a TiO(2) anatase nanoparticle have been investigated in detail, as a model for the corresponding dye-sensitized solar cells (DSSCs). The combination of density functional tight-binding (DFTB), density functional theory (DFT), and time-dependent DFT (TDDFT) approaches are employed. To understand the effects of the linker part in the TPA organic dyes on the energy conversion efficiency of the DSSCs, C217 and C206, which share the same donor and anchor parts but different linker parts, are theoretically evaluated. Our results show that compared with C206 containing just one thienothiophene unit as the linker, for C217 the introduction of one electron-rich 3,4-ethylenedioxythiophene group to the linker part results in stronger couplings with the TiO(2) conduction band and more efficient electron transfer. This difference contributes to the higher efficiency of C217 in DSSCs experiments. This study is expected to assist the molecular design of new and more efficient TPA-based organic dyes for the optimization of the DSSCs.