Design and synthesis of self-included pillar[5]arene-based bis-[1]rotaxanes

Two strategies for the design of new pillar[5]arene-based mechanically self-interlocked molecules (MSMs) are reported here. The first strategy is based on the construction of an intermediate pseudo[1]rotaxane followed by the desired bis-[1]rotaxane. The other one is based on the construction of the desired bis-[1]-rotaxane directly via a condensation reaction through host-guest interactions between a mono-functionalized pillar[5]arene and the axle. This compound has interesting self-assembly properties in methanol and some extended applications of this compound will be reported in the near future.     

Transformation of Thia[7]helicene to Aza[7]helicenes and [7]Helicene-like Compounds via Aromatic Metamorphosis

[n]Helicenes with helically twisted structures have attracted increasing interest owing to their unique properties. Therefore, it has been an important issue to develop facile synthetic methodologies which allow access to a variety of [n]helicenes. Here we report the synthesis of [7]helicenes and [7]helicene-like compounds from the thia[7]helicene as a common starting material. Desulfurative dilithiation of the thia[7]helicene and the subsequent reaction with silicon and phosphorus electrophiles afforded the silole- and phosphole-fused [7]helicene-like compounds, respectively. The cyclopentadiene-fused [7]helicene-like compound and the pyrrole-fused aza[7]helicenes were also successfully synthesized via twofold S_NAr reactions of the thia[7]helicene S,S-dioxide with the carbon and nitrogen nucleophiles, respectively. The thia[7]helicene S,S-dioxide showed a slightly red-shifted absorption spectrum than the parent thia[7]helicene, which was well demonstrated by the theoretical calculations. The substituents on the silicon atom of silole-fused [7]helicene-like compounds have little impact on the longest absorption maximum. Such little effect of the substituents on absorption properties was also observed for cyclopentadiene-fused [7]helicene-like compounds and aza[7]helicenes and was well demonstrated by the theoretical calculations. The thia[7]helicene S,S-dioxide and the silole-fused [7]helicene-like compound exhibited bright blue emission, and the cyclopentadiene-fused [7]helicene-like compound and the aza[7]helicenes showed strong violet emission. Each single enantiomer of the aza[7]helicenes showed circularly-polarized luminescence with the dissymmetry factors of 4.2~4.4 × 10⁻³.     

A practical route for synthesizing a PET ligand containing [F]fluorobenzene using reaction of diphenyliodonium salt with [F]F

The aim of this study was to develop a practical route for preparing a fluorine-18 ([¹⁸F]) labelled ligand ([¹⁸F]1) containing [¹⁸F]fluorobenzene ring by employing the reaction of diphenyliodonium salt with [¹⁸F]F⁻. Diphenyliodonium tosylate (2) was synthesized from tributylphenylstannyl compound (6) with [hydroxy(tosyloxy)iodo]benzene (7). Using this method, [¹⁸F]DAA1106 ([¹⁸F]3a), a positron emission tomography ligand for imaging peripheral-type benzodiazepine receptor, was prepared.     

Synthesis of a distanna [2]ferrocenophane and reactivity of [2]ferrocenophanes towards elemental sulfur and selenium

Here we report the synthesis and crystal structure of a new [2]ferrocenophane [Fe(η⁵-C₅H₄)₂(SntBu₂)₂] with a sterically demanding distannanediyl bridge. The reactivity of the title compound towards selected main group elements was examined and in addition, this reactivity pattern was established for the related diboranediyl bridged [2]ferrocenophane [Fe(η⁵-C₅H₄)₂(BNMe₂)₂].     

Tricyclo[4.2.2.22,5] dodecane and Tricyclo [4.2.2.12,5]undecane. Preliminary communication

A synthesis of tricyclo [4.2.2.2^2,5]dodecane ( 19 ), a novel tricyclic C₁₂H₂₀ compound, is described. The key intermediate ketone 13 was prepared either from the C₁₀-photodimer 1 of cyclopentadienone or the C₁₁-cycloaddition products 11 and 12 . 13 was also transformed to tricyclo [4.2.2.1^2,5]undecane ( 8 ).     

Alkylation of 1-hydroxy-1H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 5,7-dioxide

Alkylation of 1-hydroxy-1H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 5,7-dioxide 1 and its silver salt 10 with different alkylating agents (diazomethane, diazoacetone, bromoacetone, α-bromoacetophenone, methyl iodide, methyl vinyl ketone) was studied. Alkylation of compound 1 with diazo compounds and salt 10 with halocompounds results predominantly in O-alkylation products, 1-alkoxy-1H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 5,7-dioxides. The Michael reaction of compound 1 with methyl vinyl ketone involves the triazole nitrogen atom to give 1-(3-oxobutyl)-1H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 3,4,6-trioxide. The structures of the compounds synthesized were established by ¹H, ¹³C, ¹⁴N NMR spectroscopy and mass spectrometry.     

The synthesis of novel polycyclic heterocyclic ring systems.. Benzo[e][1]benzothieno[3,2-g][1]benzothiophenes

The novel polycyclic heterocyclic ring system compound, methyl 3-chlorobenzo[e][1]benzothieno-[3,2-g][1]benzothiophene-2-carboxylate was synthesized. The assignment of its ¹H and ¹³C nmr spectra was also accomplished by utilizing two-dimensional nmr methods.     

[5]Rotaxane and [5]Pseudorotaxane Based on Cucurbit[6]uril and Anchored to a Meso-tetraphenyl Porphyrin

Water soluble [5]rotaxane and [5]pseudorotaxane based on cucurbit[6]uril and anchored to a meso-tetraphenyl porphyrin have been synthesized and characterized by spectroscopic methods (¹H-NMR, ¹³C-NMR and UV), and by elemental analysis, and mass spectrometry. The preliminary results of the pH-driven switching properties of [5]rotaxane investigated through ¹H-NMR spectroscopy are reported. These results were compared with those obtained from a model porphyrin, which was prepared by the de-threading cucurbit[6]uril from [5]pseudorotaxane under basic conditions.Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Cucurbit[5]uril, Decamethylcucurbit[5]uril and Cucurbit[6]uril. Synthesis, Solubility and Amine Complex Formation

A simple way to prepare cucurbit[5]uril is described. The macrocycles of the cucurbituril type are nearly insoluble in water. The solubilities of cucurbit[5]uril, decamethylcucurbit[5]uril and cucurbit[6]uril in hydrochloric acid, formic acid and acetic acid of different concentrations have been investigated. Due to the formation of complexes between cucurbit[n]urils and protons the solubility increases in aqueous acids. The macrocyclic ligands are able to form complexes with several organic compounds. Thus, the complex formation of the cucurbituril macrocycles with different amines has beenstudied by means of calorimetric titrations. The reaction enthalpy gives noevidence of the formation of inclusion or exclusion complexes. ¹H-NMR measurements show that in the case of cucurbit[5]uril and cucurbit[6]uril the organic guest compound is included within the hydrophobic cavity. Decamethylcucurbit[5]uril forms only exclusion complexes with organicamines. This was confirmed by the crystal structure of the decamethylcucurbit[5]uril-1,6-diaminohexane complex.     

Synthesis of 2-dichloromethyl-2-methyl [2-14C]-1,3-dioxolane

The labelled compound was prepared by chlorination of [2-¹⁴C]acetone obtained from the barium salt of [1-¹⁴C]acetic acid by pyrolysis. The reaction product 1,1-dichloro [2-¹⁴C]acetone was converted to 2-dichloromethyl-2-methyl [2-¹⁴C]-1,3-dioxolane by condensation with ethylene glycol in the presence of thionyl chloride. Radiochemical yield: 62% based on [1-¹⁴C]acetic acid.     

The Synthesis of 5,6-Disubstituted Bicyclo[2.1.1]hexenes and 3,5-Disubstituted Tricyclo[2.2.0.02,6]hexanes

There are relatively few methods for synthesizing bicyclo[2.1.1]-hexenes and tricyclo[2.2.0.0^2,6]hexanes.¹ However, now that benzvalene (I), the highly strained structural isomer of benzene has become a readily available compound,² it is possible to prepare disubstituted compounds like II and III in a straightforward fashion.     

Synthesis of two novel ring systems via photocyclization: Thieno[2′,3′:4,5]thieno[2,3-c][1,10]phenanthroline and thieno[3′,2′:4,5]thieno[2,3-c][1,10]phenanthroline

The synthesis of thieno[2′,3′:4,5]thieno[2,3-c][1,10]phenanthroline ( 5 ) and thieno[3′,2′:4,5]thieno-[2,3-c][1,10]phenanthroline ( 10 ) are described. Each compound was obtained in four steps from known starting materials. The basic skeleton of the molecule and of the phenanthroline ring were formed via photocyclization. The total assignment of ¹H-nmr spectra was accomplished with the aid of two-dimensional nmr methods.     

The synthesis of 11H-1,2,4-triazolo[4,3-b]pyridazino[4,5-b]indoles,11H-tetrazolo[4,5-b]pyridazino[4,5-b]indoles and 1,2,4-triazolo[3,4-f]-1,2,4-triazino[4,5-a]indoles

This paper describes the synthesis of the previously unknown 11H-1,2,4-triazolo[4,3-b]pyridazino[4,5-b]indoles (2) and 11H-tetrazolo[4,5-b]pyridazino[4,5-b]indoles (3) from 4-hydrazino-5H-pyridazino[4,5-b]indoles (1) , as well as the synthesis of 1,2,4-triazolo[3,4-f]-1,2,4-triazino-[4,5-a]indoles (10) from 2-indolecarbohydrazide (4) . Compounds 2 were obtained by acylation of compounds 1 , followed of thermal cyclization and compounds 3 by treating compounds 1 with nitrous acid. The reactions of compound 4 with formic acid or ethyl orthoformiate gave 1,2-dihydro-1-oxo-1,2,4-triazino[4,5-a]indole (6) . Treating this last compound with phosphorus oxychloride or phosphorus pentasulfide, followed by hydrazine, gave 1-hydrazino-1,2,4-triazino-[4,5-a]indole (9) . Acylation of this last compound, followed of cyclization gave compounds 10 . All the compounds were characterized by elemental analysis and ir and ¹H-nmr spectra.     

Differentiation between [1,2,4]triazolo[1,5‐a] pyrimidine and [1,2,4]triazolo[4,3‐a]‐ pyrimidine regioisomers by 1H?15N HMBC experiments

The condensation of malonoaldehyde derivatives with either a 3‐amino‐[1,2,4]‐triazole or a 3,5‐diamino‐[1,2,4]‐triazole precursor was studied. In agreement with previous reports, two different bicycles, namely, bearing the regioisomeric [1,2,4]triazolo[1,5‐a]pyrimidine ( 1 ) or[1,2,4] triazolo [4,3‐a]pyrimidine ( 2 ) structural surrogates, could be obtained. We found that, depending on the triazole precursor, only one regioisomer resulted, either of the 1 or 2 series. We also observed that these two structural surrogates could be unambiguously differentiated by indirectly measuring their ¹⁵N chemical shifts by ¹H? ¹⁵N HMBC experiments. The occasional conversion of [1,2,4]triazolo[4,3‐a]pyrimidines to the [1,2,4]triazolo[1,5‐a]pyrimidine counterparts could be unequivocally determined by ¹⁵N NMR data. Copyright © 2010 John Wiley & Sons, Ltd.     

Heterotricyclodecane XXVII. Ein weiterer Zugang zu 2,6-Dioxatricyclo [3.3.2.03,7]decan

A Further Approach to 2,6-Dioxatricyclo[3.3.2.0^3,7]decane A further synthesis of 2,6-dioxatricyclo[3.3.2.0^3,7]decane ( 10 ) is described by bridging the 9-oxabicyclo[4.2.1]non-7-en-3endo-ol ( 9 ). The latter compound was prepared by ring expansion starting from the known 8-oxabicyclo[3.2.1]oct-6-en-3-on ( 1 ).     

Crystal structure of 6-ferrocenyl-3-phenyl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole

A new compound of 6-ferrocenyl-3-phenyl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole is synthesized and its single crystal structure is determined by X-ray diffraction method. The compound belongs to the monoclinic P2₁/c space group with cell parameters: a = 10.5523(12) Å, b = 13.8414(16) Å, c = 11.4303(13) Å, V = 1603.5(3) ų.     

Tetrakisdehydro[18]annuleno[20]annulene

Tetrakisdehydro[18]annuleno[20]annulene has been synthesized. The ¹H NMR spectra clearly indicate the induction of dia- and paramagnetic ring currents in 18- and 20-rings, respectively. A marked suppression of the diatropicity in the 18π moiety was observed being in the same trend in other tetrakisdehydro[4n]annuleno[4n′+2]annulenes. The ¹H NMR spectroscopic behavior of the annulenoannulenes is consistent with theoretical conclusion.     

The synthesis of novel polycyclic heterocyclic ring systems. 3. Synthesis and NMR spectroscopy of 15-chloro[1]benzo-thieno[2″,3″:3′,4′]naphtho[1′,2′:4,5]thieno[2,3-c]quinoline

The polycyclic heterocyclic compound with a novel ring system, 15-chloro[1]benzothieno[2″,3″:3′,4′]-naphtho[1′,2′:4,5]thieno[2,3-c]quinoline was synthesized via photocyclization of 3-chloro-N-phenyl[1]-benzothieno[2′,3′:3,4]naphtho[2,1-b]fhiophene-2-carboxamide followed by chlorination with phosphorus oxychloride. The assignment of its ¹H and ¹³C nmr spectra was accomplished by utilizing two-dimensional nmr methods.     

Synthesis and biological evaluation of 3-{[4-(4-[18F]fluorophenyl)methyl] piperazin-1-yl}-methyl-1H-pyrrolo[2,3-b]pyridine for in vivo studies of dopamine D4 receptor

The compound 3-{[4-(4-[¹⁸F]fluorophenyl)methyl]piperazin-1-yl}-methyl-1H-pyrrolo[2,3-b]pyridine ([¹⁸F]3), which is an analogue of L-745,870 binding D₄ This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of a new calix[n]pyrrole: meso-pentaspirocyclohexyl calix[5]pyrrole

We describe the first synthesis of the novel meso-pentaspirocyclohexyl calix[5]pyrrole 2b. Anion-guest properties of the new compound were evaluated with respect to fluoride, chloride, and bromide tetrabutylammonium salts by ¹H NMR titration techniques in deuterated dichloromethane at 22 °C by following the induced shifts in the NH resonances upon complexation.