Reversible 1,3‐dipolar cycloaddition of dimethyl 2‐thiono‐1,3‐dithiole‐4,5‐dicarboxylate with dimethyl acetylenedicarboxylate

It was shown that dimethyl 2‐thiono‐1,3‐dithiole‐4,5‐dicarboxylate ( 2 ) and dimethyl acetylenedicarboxylate (DMAD) undergo a 1,3‐dipolar cycloaddition to produce a short‐lived ylide intermediate ( 3 ). The 1,3‐dipolar cycloaddition took place even at room temperature, although sluggishly, but took place much more rapidly under application of a high pressure of 500 MPa. The 1,3‐dipolar cycloaddition is reversible and the ylide 3 immediately splits into 2 and DMAD. When the reaction of 2 with DMAD was carried out at room temperature without solvent, a spiro‐1,3‐dithiole ( 11 ) was formed in 11% yield, whereas the reaction at 150°C provided a thiophene derivative ( 13 ) in 41% yield. It was found that 11 undergoes a thermal rearrangement to 13 . Results of attempted chemical trapping of the ylide 3 are also reported. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:434–440, 2000     

Highly Selective Fluorescence Detection for Mercury (II) Ions in Aqueous Solution Using Water Soluble Conjugated Polyelectrolytes

A highly selective assay method has been developed to detect mercury (II) (Hg²⁺) ions using cationic conjugated polymer (CCP). The transduction mechanism is based on a Hg²⁺ promoted reaction. In the absence of Hg²⁺ ions, the CCP can form the complex with an anionic 1,3‐dithiole‐2‐thione derivative through electrostatic interactions. The fluorescence of CCP is efficiently quenched by 1,3‐dithiole‐2‐thione derivative via an electron transfer process. Upon adding Hg²⁺ ions, the transformation of 1,3‐dithiole‐2‐thione into 1,3‐dithiole‐2‐one inhibits the quenching, and the fluorescence of CCP is recovered. Distinguishing aspects of this assay include the signal amplification of CCPs and a specific Hg²⁺ promoted reaction. By triggering the change in the emission intensity of CCP, it is possible to detect Hg²⁺ ions in aqueous solution.

     

Three Component Reaction: An Efficient Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and Thiones Using Heterogeneous Catalyst

Fluoroboric acid supported on silica gel (HBF₄‐SiO₂) catalyzes efficiently the three component condensation of an aldehyde, a 1,3‐dicarbonyl compound and urea or thiourea to afford the corresponding 3,4‐dihydropyrimidin‐ 2(1H)‐ones and thiones in high yields. The ambient conditions, fast reaction rates, and excellent product yields are the important characteristics of this reaction.     

Structural Aspects of 5‐methylthio‐1‐oxa‐6,6a δIV‐dithia‐2‐azapentalenes

Alkylation of 5‐[1‐hydroxyiminoalkyl]‐1,2‐dithiole‐3‐thiones using methyl iodide in the presence of sodium hydroxide gives derivatives which may be considered as being 5‐methylthio‐1‐oxa‐6,6a δ^IV‐dithia‐2‐azapentalenes with quantitative yields. The structure of oxadithiazapentalene attributed to the alkylation products is founded on X‐ray analysis and NMR and IR data.     

Unexpected Microwave Reaction of 1,3‐Disubstituted Imidazolium Salts: A Novel Synthesis of 1,3‐Disubstituted Imidazole‐2‐thiones

Microwave‐promoted reaction of 1,3‐disubstituted imidazolium salts with potassium thioacetate or potassium thiocyanate under solvent‐free conditions provided a rapid and efficient synthesis of 1,3‐disubstituted imidazole‐2‐thiones.     

Synthesis of dithiafulvene–quinone donor–acceptor systems: isolation of a Michael adduct

π‐Conjugated donor–acceptor systems based on dithiafulvene (DTF) donor units and various acceptor units have attracted attention for their linear and nonlinear optical properties. The reaction between p‐benzoquinone and a 1,3‐dithiole phosphonium salt, deprotonated by lithium hexamethyldisilazide (LiHMDS), gave a product mixture from which the Michael adduct [systematic name: dimethyl 2‐(3‐hydroxy‐6‐oxocyclohexa‐2,4‐dien‐1‐ylidene)‐2H‐1,3‐dithiole‐4,5‐dicarboxylate], C₁₃H₁₀O₆S₂, was isolated. It is likely that one of the unidentified products obtained previously by others from related reactions could be a similar Michael adduct.     

Synthese,Struktur und Charakterisierung von Titan‐, Zink‐, Nickel‐ und Palladium‐Thioether‐Thiolat‐Komplexen heterocyclischer 1,2‐Dithiolate

Synthesis, Structures, and Characterization of Titanium, Zinc, Nickel, and Palladium Thioether Thiolate Complexes of Heterocyclic 1,2‐Dithiolates Synthesis and properties of mixed ligand complexes of thioether thiolate ligands 4‐methylthio‐1,3‐dithiole‐2‐one‐5‐thiolate (dmidCH₃), 4‐methylthio‐1,3‐dithiole‐2‐thione‐5‐thiolate (dmitCH₃), and 4‐methylthio‐1,3‐dithiole‐2‐selone‐5‐thiolate (dmiseCH₃) are described. The x‐ray structures of CpTi(dmidCH₃)₂ (Cp′ = methylcyclopentadienyl), of two polymorphic structures of (tmeda)Zn(dmitCH₃)₂ [tmeda = 1,2‐bis(dimethylamino)ethane], of (dppe)Ni(dmitCH₃)₂, and (dppe)Pd(dmitCH₃)₂ [dppe=1,2‐bis(diphenylphosphino)ethane] are reported.     

Studies on the Flash Vacuum Thermolysis of Thiones of Selected N‐, O‐, and S‐Heterocycles

Thermal decomposition of thiones of selected N‐, O‐ and S‐heterocycles under flash vacuum thermolysis conditions was investigated. In the case of six‐membered 4H‐3,1‐benzoxathiin‐4‐thione 6 , the course of the reaction depended on the substitution pattern at C(2) (Scheme 3). Thus, the 2‐unsubstituted derivative 6a led to the unstable product 2 , which upon treatment with MeOH was converted quantitatively into methyl 2‐mercaptobenzoate ( 7 ). The analogous thermolysis of the 2,2‐dimethyl derivative 6b yielded 2‐methyl‐4H‐1‐benzothiopyran‐4‐thione ( 8 ) as a sole product. In the case of thiophthalide derivatives 15 , a thermal rearrangement in the gas phase leading to the corresponding benzo[c]thiophen‐1(3H)‐ones 16 in high yields was observed (Scheme 6). Unexpectedly, thionation of 1,3‐oxathiolan‐5‐one 17 with Lawesson's reagent under standard conditions led to 1,2‐dithietane derivative 19 , which, after the gas‐phase thermolysis, underwent a ring enlargement to yield 3H‐1,2‐dithiole 20 (Scheme 7). The six‐membered 4H‐1,3‐benzothiazine‐4‐thione 21 was shown to give three products: phenanthro[9,10‐c]‐1,2‐dithiete ( 22 ), 3H‐1,3‐benzodithiole‐3‐thione ( 23 ), and N‐(3H‐1,2‐benzodithiol‐3‐ylidene)prop‐2‐en‐1‐amine ( 24 ) (Scheme 8). The latter is the product of the initial reaction, whereas 22 and 23 are postulated to be formed as secondary products of the conversion of the intermediate 6‐(thioxomethylene)cyclohexa‐2,4‐diene‐1‐thione ( 26 ) (Schemes 9 and 10).     

Bis(1,3‐dithiol‐2‐ylidene)‐Substituted Subtriazachlorin: A Subphthalocyanine Analogue with Redox Properties

Bis(1,3‐dithiol‐2‐ylidene)‐substituted subtriazachlorin was formed because of an unusual reaction of a 1,3‐dithiole‐2‐one‐fused subphthalocyanine in a triethylphosphite‐mediated tetrathiafulvalene synthesis. In this novel molecule, the bis(1,3‐dithiol‐2‐ylidene)ethane moiety and subtriazachlorin structure are fused, resulting in an electron‐donating ability and broad absorption in the near‐infrared region.     

Synthesis of 4H‐1,3‐oxathiin‐4‐ones by reaction of α‐diazo‐β‐diketone with thiones

A series of 2,2‐disubstituted 5,6‐diphenyl‐4H‐1,3‐oxathiin‐4‐ones was synthesized by cycloaddition of thiones with benzoylphenylketene, which was generated by the thermal Wolff rearrangement of 2‐diazo‐1,3‐diphenyl‐1,3‐propanedione. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:630–632, 2001     

Synthesis of imidazoles as novel emivirine and S‐DABO analogues

5‐Alkyl‐4‐benzyl‐1,3‐dihydroimidazol‐2‐ones ( 3a‐d ) and 5‐alkyl‐4‐benzyl‐1,3‐dihydroimidazole‐2‐thiones (7a‐d) were prepared via Dakin West reaction on DL‐phenylalanine with the appropriate aliphatic acid anhydrides followed by hydrolysis and reaction with potassium cyanate or potassium thiocyanate. Compounds 3a‐d were alkylated with ethoxymethyl chloride to give the alkylated imidazoles 5a‐d which were considered analogues of Emivirine with deletion of carbonyl group at the 4‐position. Alkylation of 7a‐d afforded the corresponding S‐alkylated derivatives 8a‐p which in a similar way were considered analogues of S‐DABO. However all the imidazole derivatives were devoid of activity against HIV.     

Cluster—cracking Reaction,a New Method to Synthesize Unsymmetrical Dithiolate Complexes for the Study of Third—Order Nonlinear Optical Properties

A new coluster-cracking method to synthesize dithiolate metal complexes was reported and four unsymmetric complexes with formula(Me4N)2[M(Ln)(SPh)2](M=Cd and Zn,L1=dmit=1,3-dithiole-2-thione4-5,dithiolate,L2=dmid=1,3-dithiole-2-one-4,5-dithiolate,SPh=thiophenolate)(1-4)were characterized by elemental analysis,IR,UV NMR spectra and so on.The advantages of this method are summarized in two aspects:(1) the preparation is very convenient;(2) the reaction usually completed giving the product with high pruity.The crystal structure of 1 showed that the bond distances of Cd(Ⅱ）to the sulfur of the thiophenolate group are shorter than those of Cd(Ⅱ）to the sulfur of dmit,so that the thiophenolate group does not be replaced in the reaction and thmixed ligand complexes are the dominant produxts.The dmit complexes showed well third-order NLO properties,but not of the dmid complexes,although dmid is an analogue to dmit.     

Synthesis of (4Z)‐4‐(Arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones by the Reaction of Ethyl (2Z)‐3‐Aryl‐2‐isothiocyanatoprop‐2‐enoates with Organolithium Compounds

A convenient one‐pot method for the preparation of (4Z)‐4‐(arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones 2 and 3 from ethyl (2Z)‐3‐aryl‐2‐isothiocyanatoprop‐2‐enoates 1 , which can be easily prepared from ethyl 2‐azidoacetate and aromatic aldehydes, has been developed. Thus, these α‐isothiocyanato α,β‐unsaturated esters were treated with organolithium compounds, including lithium enolates of acetates, to provide 5‐substituted (4Z)‐4‐(arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones, 2 , and 2‐[(4Z)‐(4‐arylmethylidene)‐5‐ethoxy‐2‐thioxo‐1,3‐oxazolidin‐5‐yl]acetates, 3 .     

新型1,3-二硫杂环戊烯-2-硫酮衍生物的合成

通过4,5－二硫基－1,3－二硫杂环戊烯－2－硫酮（dimt）的锌配合物和相应的卤化物反应,成功地合成了3种未见报道的1,3－二硫杂环戊烯－2－硫酮衍生物。讨论了制备这些化合物的反应条件。用IR、^1HNMR和MS对这些化物进行了表征。     

Reduction of Thiocarbonyl Compounds with Lithium Diisopropylamide

Treatment of 4,4‐disubstituted 2‐phenyl‐1,3‐thiazole‐5(4H)‐thiones with lithium diisopropylamide (LDA; LiNⁱPr₂) in THF at ?78° yielded the corresponding 1,3‐thiazole‐5(4H)‐thioles in moderate yields. Sequential treatment with LDA and MeI under the same conditions led to the 5‐methylsulfanyl derivatives. Similarly, reaction of some cycloalkanethiones as well as diaryl thioketones with LDA and MeI gave cycloalkyl methyl sulfides and diarylmethyl methyl sulfides, respectively. A reaction mechanism via H transfer from LDA to the thiocarbonyl C‐atom via a six‐membered transition state is proposed for this unprecedented reduction of the C?S bond.     

Sodium Tetrafluoroborate as a New and Highly Efficient Catalyst for One‐Pot Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐Ones and Thiones

Sodium tetrafluoroborate (NaBF₄) is found to catalyze the three component condensation of an aldehyde, 1,3‐dicarbonyl compound and urea or thiourea to afford the corresponding 3,4‐dihydropyrimidin‐2(1 H)‐ones and thiones in high yields. This method is very useful for the synthesis of a wide range of 3,4‐dihydropyrimidin‐2(1 H)‐ones and thiones from aromatic, heterocyclic, α,β‐unsaturated aldehydes and aliphatic aldehydes.     

An efficient protocol for the one‐pot synthesis of 4‐(2‐(4‐bromophenyl)‐1,2,3‐triazol‐4‐yl)‐3,4‐dihydropyrimidin‐2(1H)‐ones/thiones catalyzed by Mg(NO3)2

A series of novel 4‐(2‐(4‐bromophenyl)‐1,2,3‐triazol‐4‐yl)‐3,4‐dihydropyrimidin‐2(1H)‐ones/thiones were prepared by condensing 2‐(4‐bromophenyl)‐4‐formyl‐1,2,3‐triazole with 1,3‐dicarbonyl compound and urea or thiourea using Mg(NO₃)₂ as an efficient and cheap catalyst. The satisfactory results were obtained with excellent yields and short reaction time. J. Heterocyclic Chem., (2010).     

Synthesis,Characterization, and X‐ray Crystal Structures of (Diphosphine)Ni(dmit) and (Diphosphine)Ni(dmio) (Diphosphine = dppv,dppb) Complexes

Four complexes with the ligands dmit and dmio were synthesized. Reaction of (PhCO)₂(dmit) and (PhCO)₂(dmio) with MeONa afforded the intermediates 2‐thioxo‐1,3‐dithiole‐4,5‐dithiolate dianion and 2‐oxo‐1,3‐dithiole‐4,5‐dithiolate dianion, respectively. Reaction of the two dianions with (diphosphine)NiCl₂ [diphosphine = (Z)‐1, 2‐bis(diphenylphosphanyl)ethane (dppv), 1,2‐bis(diphenylphosphanyl)benzene (dppb)] gave (dppv)Ni(dmit) ( 1 ), (dppb)Ni(dmit) ( 2 ), (dppv)Ni(dmio) ( 3 ), and (dppb)Ni(dmio) ( 4 ). This synthesis route was found to be an efficient pathway to prepare dmit and dmio ligand complexes. Complexes, 1 – 4 were fully characterized by elemental analysis and IR, ¹H NMR, ¹³C NMR, and ³¹P NMR spectroscopy. In addition, the molecular structures of 1 , 3 and 4 were established by X‐ray diffraction.     

Studying the synthesis of 4‐tert‐butyl‐1,3‐dihydroimidazol‐2‐ones and their corresponding thiones

4‐tert‐Butyl‐1,3‐dihydroimidazol‐2‐ones and 1,3‐dihydroimidazol‐2‐thiones were synthesized from 1‐amino‐3,3‐dimethylbutanone and subjected to alkylation reactions. The latter compounds were S‐alkyl‐ated with iodoacetamide under alkaline conditions. The N¹ N³‐unsubstituted derivative was iodinated and subsequently alkylated with alkylation reagents which previously have been used for the synthesis of anti‐HTV active imidazoles. Unfortunately, the present products were devoid of activity against HTV.     

硅烷基取代苯并二硫杂环戊烯的合成及电化学性质

以苯并-1,3-二硫杂环戊烯为原料,通过金属化反应以及锂化二硫杂环戊烯与氯代硅烷反应合成了系列2-硅烷基取代苯并-1,3-二硫杂环戊烯化合物.测定了化合物的氧化电位,发现硅的引入导致苯并-1,3-二硫杂环戊烯的氧化电位明显降低,给体的给电子能力增强.