Short Synthesis of Enantiopure Thieno[2,3‐f]triazolo[1,5‐a][1,4]diazepines and Thieno[2,3‐f][1,4]diazepin‐5‐ones

Starting from 2‐carboxy‐3‐thenylazide 1 and enantiopure amines 2 as the chiral building blocks, we developed a two‐step synthesis of the title compounds involving an intramolecular azide cycloaddition as the key step.     

Generation and structure determination of 5,6‐bis(methylthio)‐4,7‐diethylbenzo[1,2,3]trithiole dication MBT(2+)

5,6‐Bis(methylthio)‐4,7‐diethylbenzo‐[1,2,3]‐trithiole [MBT] was oxidized with two equivalents of SbCl₅ to produce a dication, MBT(2+)ċ2SbCl, as a stable, dark‐brown solid. MBT(2+) was unexpectedly silent for ¹H‐NMR in CD₃CN, whereas it was active for ESR, suggesting that MBT(2+) is a triplet‐state dication MBT(2+)‐T. Meanwhile, treatment of 5‐ methylsulfinyl‐6‐methylthio‐4,7‐diethylbenzo[1,2,3]‐ trithiole [MBTMO] with D₂SO₄ produced MBT(2+), whose ¹H‐NMR gave no signals, whereas the solution is active for ESR. These results imply that MBT(2+) prepared from MBTMO is a triplet‐state dication, and a singlet‐state dication, MBT(2+)‐S, initially generated by acidification of MBTMO, isomerized to the triplet‐state dication, MBT(2+)‐T. Since MBT(2+)‐T is active for ESR at room temperature, two molecules of MBT(2+)‐T should form a spin pair in the solution with a sufficient distance between the two radical centers. The structures of MBT(2+)‐S and MBT(2+)‐T were optimized with the DFT method at the B3LYP6‐31G** level. The total energy difference between them was calculated to be 7.90 kcal/mol; MBT(2+)‐T was shown to be more stable than MBT(2+)‐S. A treatment of MBTMO with SbCl₅ gave a 1:1 complex. The structure of the complex was determined with X‐ray crystallography, which showed that the complex is the corresponding sulfonium salt, MBTMOċSbCl₅. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:111–222, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20078     

Synthesis of novel 1,4‐dihydropyrido[3′,2′:5,6]thiopyrano[4,3‐c]‐pyrazoles and 5H‐pyrido[3′,2′:5,6]thiopyrano[4,3‐d]pyrimidines as potential antiproliferative agents

The synthesis of new planar derivatives characterized by the presence of a pyridothiopyranopyrazole or pyridothiopyranopyrimidine nucleus, carrying a substituted aryl group, is reported. The novel 1,4‐dihydropyrido[3′,2′:5,6]thiopyrano[4,3‐c]pyrazole derivatives were obtained by condensation of 2,3‐dihydro‐3‐hydroxymethylenethiopyrano[2,3‐b]pyridin‐4(4H)‐ones with appropriate hydrazines. The preparation of 2‐substituted pyrido[3′,2′:5,6]thiopyrano[4,3‐d]pyrimidines was accomplished from the intermediate 2,3‐dihy‐dro‐3‐dimethylaminomethylenethiopyrano[2,3‐b]pyridin‐4(4H)‐ones by reaction with the appropriate binucleophile amidines. The antiproliferative activity of some new products was tested by an in vitro assay on human tumour cell lines (HL‐60 and HeLa), but none of them showed any significant effects in the tests performed. Accordingly, linear flow dichroism measurements indicated their inability to form a molecular complex with DNA.     

Synthesis and biological evaluation of benzo[7,8]chromeno[5,6‐b][1,4]oxazin‐3‐ones

The O‐methylmonoximes 2,3 of stenocarpoquinone‐A and β‐lapachone reacted with methyl phenylacetate to give 1,4‐benzoxazine derivatives 8a, 8b and oxazole 11a. Compound 8a was transformed to compounds 13_I , 13_II , 14. Treatment of compound 14 with osmium tetroxide afforded compounds 15 , 16 and esterification of the latter gave the bis‐ and mono‐ esters 17_I , 17_II , 18. All products are strongly fluorescent. Compounds 8a,b , 11a , 13–18 (azabenzo analogues of khellactones) were tested for their ability to interact with DPPH, to compete with dimethylsulfoxide for hydroxyl radicals, to inhibit soybean lipoxygenase and trypsin activities in vitro. Compounds 16 and 17_II were found to compete significantly with dimethylsulfoxide for hydroxyl radicals, whereas compounds 8a , 11a , 14 and 17_I were found to inhibit strongly soybean lipoxygenase.     

Highly effective binding of methyl viologen dication and its radical cation by p-sulfonatocalix[4,5]arenes

The binding behaviors and thermodynamic origins of p-sulfonatocalix[4]arene (C4AS) and p-sulfonatocalix[5]arene (C5AS) with methyl viologen (MV2+) have been investigated by the methods of isothermal titration calorimetry, NMR, and cyclic voltammetry, showing that the binding abilities of C4AS and C5AS and their host selectivity are dramatically pH-controlled, which is closely discussed from the viewpoint of thermodynamics. Moreover, the radical form of MV+* can also be effectively included by C4AS and C5AS.     

One-pot synthesis of benzo[f]indole-4,9-diones from 1,4-naphthoquinones and terminal acetylenes

In this paper, a concise one-pot method for the construction of benzo[f]indole-4,9-dione motifs is described. These transformations proceed via a sequential palladium- and copper-catalyzed coupling reaction of 1,4-naphthoquinones with terminal acetylenes, followed by a copper-catalyzed intramolecular cyclization reaction of the resulting coupling product.     

The Synthesis of 2,11‐Diamino‐4,9‐diphenyl‐4,9‐dihydrobenzo [f] pyrano[3,2‐h]chromene‐3,10‐dicarbonitrile Derivatives using Triethanolammonium Acetate as a Green Ionic Liquid

Triethanolammonium acetate [TEA ][HOAc ] was used as a green ionic liquid and successfully utilized for the multi‐component synthesis of 2,11‐diamino‐4,9‐diphenyl‐4,9‐dihydrobenzo[f]pyrano[3,2‐h]chromene‐3,10‐dicarbonitrile derivatives as new compounds by the reaction of 2,3‐naphthalenediol with malononitrile and various aldehydes. Mild reaction conditions and high yields are some of the advantages of this method. These compounds were identified by IR , NMR spectroscopy and mass analysis.     

Synthesis of new benzo[h]‐ and benzo[f]chromeno[2,3‐b]‐pyridine‐5‐ones

A number of new benzo[h]‐ and benzo[f]chromeno[2,3‐b] pyridine‐5‐ones derivatives were synthesized from benzo[h]‐ and benzo[f]‐chromone‐carbonitriles and amino‐benzo[h]‐ and benzo[f]chromone‐carbaldehydes. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:2–7, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20152     

Hydrolytic stability and high Tg of polyimides derived from the novel 4,9‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]‐diamantane dianhydride

This work reports the synthesis and characterization of diamantane‐based polyimides obtained from 4,9‐bis[4(3,4‐dicarboxyphenoxy)phenyl]diamantane dianhydride and various aromatic diamines. Interestingly, the diamantane‐based polyimides were very stable to hydrolysis. This novel polyimide exhibits a low dielectric constant (2.65–2.77), low moisture absorption (<0.67%), good solubility, high T_g and unusually high thermal stability. Dynamic mechanical analysis (DMA) reveals that the diamantane‐based polyimides have high T_g ranging from 281 to 379 °C. The high‐temperature β₁ subglass transition around 285 °C was observed in polyimide 6a derived from 2,2′‐bis(trifluoromethyl)benzidine. This class of novel diamantane‐based polyimide is very promising for electronic applications, because of its good mechanical properties, good thermal stability, low dielectric constant, excellent hydrolytic resistance, and low moisture absorption. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1673–1684, 2009     

Synthesis of New Pyrimido[5′,4′:5,6][1,4]thiazino[2,3‐b]quinoxaline Derivatives in One Step

As a continuation of our search for new heterocyclic compounds, the synthesis of pyrimido[5′,4′:5,6][1,4]thiazino[2,3‐b]quinoxaline ring system is described. A series of new derivatives of this heterocyclic system ( 3a–d ) have been synthesized through the one‐pot heterocyclization of the appropriate 5‐amino6‐methylpyrimidine‐4‐thiols and 2,3‐dichloroquinoxaline in the presence of K₂CO₃ in dimethylformamide under reflux. N‐alkylation of the synthesized compounds with alkyl halides in KOH/dimethylformamide also gave the desired new derivatives of N‐alkylated pyrimido[5′,4′:5,6][1,4]thiazino[2,3‐b]quinoxalines ( 4a–h ). All the synthesized products were characterized and confirmed by their spectroscopic and microanalytical data.     

4,9‐Dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐4,9‐dione functionalized copolymers for organic photovoltaic devices

The synthesis of conjugated polymers 1 – 5 functionalized with 4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐4,9‐dione in the backbone is reported and their use in the construction of organic solar cells is demonstrated. Increasing the molar ratio of 2,7‐dibromo‐3,8‐dihexyl‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐4,9‐dione, relative to 4,4′‐dihexyl‐5,5′‐dibromo‐2,2′‐bithiophene, in the copolymer synthesis significantly lowers the solubility of these polymers. The incorporation of highly conjugated 3,8‐dihexyl‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐4,9‐dione unit into the polymer backbone has been confirmed by UV–vis absorption. The observation of decreasing quantum yield for the emission in the order of 1 , 2 , 3 is consistent with copolymers with different comonomer content. The power conversion efficiencies of solar cells using blends of these polymers with PCBM ([6,6]‐phenyl C₆₁‐butyric acid methyl ester) were determined to be 0.11% for polymer 1 , 0.33% for 2 , and 0.26% for 3 , respectively. Under identical white light illumination, the power conversion efficiency of the device based on polymer 2 /PCBM as the active layer was three times higher compared to that of device based on polymer 1 /PCBM. Owing to the limited solubility and poor film‐forming ability of polymer 3 , the power conversion efficiency of solar cell based on 3 /PCBM blend is lower than that of 2 /PCBM blend, but is still larger than that of 1 /PCBM blend. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2680–2688, 2008     

Synthesis of Novel 7‐methylene‐6,7‐dihyrobenzo[f]Benzo[4,5]Imidazo[1,2‐d][1,4]Oxazepines via Base‐mediated Regioselective Intramolecular Hydroamination

A versatile and transition metal‐free approach for the synthesis of new 7‐methylene‐6,7‐dihyrobenzo[f]benzo[4,5]imidazo[1,2‐d][1,4]oxazepines were developed by an efficient 7‐exo‐dig regioselective hydroamination of 2‐(2‐(prop‐2‐yn‐1‐yloxy)phenyl)‐1H‐benzo[d]imidazole in the presence of potassium carbonate in DMF at 90°C.     

Synthesis of [1,4]benzodioxino[2,3‐c and 2,3‐d]pyridazinones

Reaction of chloropyridazin‐3‐one 1, 5 and 10 with catechol in the presence of potassium carbonate gave the corresponding [1,4]benzodioxino[2,3‐e and/or 2,3‐d]pyridazinones 2, 7, 8 and 11 .     

Synthesis and biological evaluation of new benzo[f]furo[2,3‐h]‐and benzo[f]pyrano[2,3‐h]coumarin derivatives.

Furocoumarins 3,5 and pyranocoumarin 7 were synthesized from the reaction of furonaphthalenediones 2,4 and pyranonaphthalenedione 6 respectively with carbethoxymethylene(triphenyl)phosphorane in refluxing DCM for 3‐6 hours or under microwave irradiation in toluene for a few minutes. Compounds 3,5,7 and their precursors were tested as anti‐inflammatory/antioxidant agents. They were found to compete significantly high DMSO for OH radicals, to scavenge O₂^? and to inhibit lipoxygenase to a high extent.     

Synthesis and characterization of new O,O‐diethyl phosphorothioates derived from substituted tetrazolo[1,5‐a]quinolin‐ 4‐ylmethanol derivatives

A simple and convenient method is developed for the synthesis of new O,O‐diethyl O‐(substituted tetrazolo[1,5‐a]quinolin‐4‐yl)methyl phosphorothioates, which has been synthesized for the first time from tetrazolo[1,5‐a] quinolines via tetrazolo[1,5‐a]quinolin‐4‐ylmethanol derivatives. The structures of the all newly synthesized compounds were elucidated by analytical and spectral methods. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 20:436–441, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20570     

4,9-Dihydrobenz[f]indole-4,9-dione derivatives synthesis and properties of 2,3,4,9-tetrahydrobenz[f]indole-2,4,9-triones and 2,3,4,9-tetrahydrobenz[f]indole-2,3,4,9-tetrones

Under the influence of amines, (3-chloro-1,4-naphthoquinon-2-yl)malonic ester is cyclized to 3-carbethoxy derivatives of 2,3,4,9-tetrahydrobenz[f]indole-2,4,9-trione, which were decarboxylated and then oxidized to 2,3,4,9-tetrahydrobenz[f]indole-2,3,4,9-tetrone derivatives. Methylation of 2,3,4,9-tetrahydrobenz[f]indole-2,4,9-triones leads to a mixture of O- and C-methyl derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 911–914, July, 1976.     

Chemical Reactivity of 4,9‐Dimethoxy‐5‐oxo‐5H‐furo[3,2‐g]chromene‐6‐Carboxaldehyde Toward Some Nucleophilic Reagents

The chemical reactivity of 4,9‐dimethoxy‐5‐oxo‐5H‐furo[3,2‐g ]chromene‐6‐carboxaldehyde (6‐formylkhellin) ( 1 ) was studied toward a diversity of nitrogen nucleophilic reagents. Reaction of carboxaldehyde 1 with some primary amines and heterocyclic amines afforded the corresponding Schiff bases. Also, the reactivity of carboxaldehyde 1 was studied toward some hydrazine derivatives, namely 7‐chloro‐4‐hydrazinoquinoline, 3‐hydrazino‐5,6‐diphenyl‐1,2,4‐triazine, N⁴‐phenylthiosemicarbazide, and S‐benzyldithiocarbazate. 6‐Formylkhellin ( 1 ) underwent ring transformation upon treatment with hydroxylamine hydrochloride producing 5‐hydroxy‐4,9‐dimethoxy‐7‐oxo‐7H‐furo[3,2‐g ]chromene‐6‐carbonitrile ( 22 ). Some pyrimidine, [1,2,4]triazolo[4,3‐a ]pyrimidine, tetrazolo[1,5‐a ]pyrimidine, and diazepine derivatives linked benzofuran were efficiently synthesized. Reaction of carboxaldehyde 1 with a variety of 1,4‐binucleophiles produced furochromone‐fused benzodiazepine, pyridotriazepine, benzoxazepine, and benzothiazepine derivatives. Some unsymmetrical thiocarbohydrazones were also synthesized. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.