Thienyl Substituents Research Articles

Functionalized (Benzotriazol-1-yl)methanes as 1,1-Dipole Synthon Equivalents in Diverse Annulations to Aromatic and Heteroaromatic Rings

The title compounds 1a−e readily undergo deprotonation and subsequent reactions with the appropriate electrophiles to form intermediates of types 4 and 7 which, upon treatment with Lewis acids, cyclize to afford fused aromatics 5 and 8. Tetrahydronaphthalene 11a, 1,2,3,4-tetrahydrochromanes (11b−d, 13), indanes (16, 18), 9,10-dihydrophenanthrenes (21a−c, 25), and tetrahydro[1,2-a]indoles (28, 30) with phenyl, substituted phenyl, and thienyl substituents were prepared in this manner.

Two Methylsulfanylmethylene Derivatives of Meldrum's Acid

Functionalization of methylsulfanylmethylene Meldrum's acid (2,2-dimethyl-1,3-dioxane-4,6-dione) with aryl or thienyl substituents, to give 5-[(p-tert-butylphenyl)(methylsulfanyl)methylene]-2,2-dimethyl-1,3-dioxane-4,6- dione, C18H22O4S, and 5-[(methylsulfanyl)(2-thienyl)methylene]-2,2-dimethyl-1,3-dioxane-4,6-dione, C12H12O4S2, results in a lengthening of the C—S single bond and the adoption of essentially a boat conformation by the Meldrum's acid heterocycle.

Synthesis and tautomerism of 2‐aryl‐ and 2‐heteroaryl derivatives of benzimidazole

AbstractBenzimidazoles containing furyl and thienyl substituents at C‐2 were prepared by condensation of o‐phenylenediamine and corresponding carboxylic acids in the presence of polyphosphoric acid. The 2‐heteroarylbenzimidazoles showed tautomerism in dimethyl sulfoxide solution while 2‐phenylbenzimidazole did not. The tautomerism appeared to be taking place by intermolecular relay of protons between stacked molecules.

ChemInform Abstract: Pyrroles from Ketoximes and Acetylene. Part 47. New Pyrroles with Furyl and Thienyl Substituents.

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Ruthenium carbonyl complexes with polyfunctional phosphine ligands

Reactions of Ru 3(CO) 12 with the polyfunctional phosphinestris (2-thienyl)phosphine and tris(diethylamino)phosphine have been investigated. The reaction of the former phosphine with Ru 3(CO) 12 yields, inter alia, the complexes Ru 3(CO) 10[P(C 4H 3S) Ru 3(CO) 10[P(C 4H 3S) 3] 2 ( 1) and Ru(CO) 3[P(C 4H 3S) 3] 2 ( 2), both of which have been characterized by X-ray diffraction studies. In 1 the two polyfunctional phosphine ligands are coordinated equatorially via their phosphorus atoms to two adjacent metal atoms of the Ru 3 triangle. In 2 the phosphorus atoms of two P(C 4H 3S) 3 ligands occupy the axial positions of the trigonal bipyramidal coordination sphere around the ruthenium atom. The six thienyl substituents are arranged in an eclipsed conformation, with all sulphur atoms pointing preferentially towards the center of the molecule. The reaction of Ru 3(CO) 12 with an excess of P(NEt 2) 3 yields the disubstituted cluster Ru 3(CO) 10[P(NEt 2) 3] 2 ( 3). The IR spectrum of 3 reveals the presence of bridging carbonyl ligands, distinguishing 3 from all previously known clusters of this type.

?-Thienyl-substituted thiopyrilium salts

The perchlorates of 2,6-di(2-thiettyl)-4-methylpyrilium and -thiopyrilium, and the isomeric 2,4-di(2-thienyl)-6-methyl derivatives, as well as the perchlorates of 2,4-di(2-thienyl)pyriliurn with tri- and tetramethyl groups in the 5,6 position have been synthesized. Their UV and PMR spectra have been studied. Based on data on Oberhauser's nuclear effect it was concluded that the sulfur atoms of 2(6)-thienyl substituents and the O(S) atoms of heteroaromatic cations are present in the cis position.

The fast atom bombardment mass spectra of furyl and thienyl silanes and germanes in comparison with their electron impact mass spectra

AbstractThe interaction of the π electron system of furyl and thienyl substituents with the silicon (or germanium) atom is less significant in fragmentation under fast atom bombardment than under electron impact. Under fast atom bombardment the primary fragmentation of the title compounds is determined by steric influence of the heteroaromatic substituents.

ChemInform Abstract: Reactions of Heteroarylhydrosilanes with Dichlorocarbene Under Phase‐Transfer Conditions.

Abstract The reactions of dimethyl(2-thienyl)-, methyl[di(2-thienyl)]-, tri(2-thienyl)- and dimethyl(2-furyl)silanes (I–IV, respectively) with dichlorocarbene generated from sodium trichloroacetate under solid-liquid phase-transfer conditions afford the corresponding dichloromethylsilanes in 38–66% yield. The reactivity of the thienylsilanes decreases with the number of electron-accepting thienyl substituents at the silicon atom. Using the competition reactions, the relative rate constants for the reaction of dichlorocarbene insertion into the SiH bond of thienyl- and furyl-silanes (I and IV) were measured. The reactivity of these silanes was found to be greater than had been expected taking as a basis the Taft σ* constants for the substituent at the silicon atom. This is apparently due to the existence of a pπ—dπ interaction between the heterocyclic π-system and the d-orbitals of silicon.

Reactions of heteroarylhydrosilanes with dichlorocarbene under phase-transfer conditions

The reactions of dimethyl(2-thienyl)-, methyl[di(2-thienyl)]-, tri(2-thienyl)- and dimethyl(2-furyl)silanes (I–IV, respectively) with dichlorocarbene generated from sodium trichloroacetate under solid-liquid phase-transfer conditions afford the corresponding dichloromethylsilanes in 38–66% yield. The reactivity of the thienylsilanes decreases with the number of electron-accepting thienyl substituents at the silicon atom. Using the competition reactions, the relative rate constants for the reaction of dichlorocarbene insertion into the SiH bond of thienyl- and furyl-silanes (I and IV) were measured. The reactivity of these silanes was found to be greater than had been expected taking as a basis the Taft σ * constants for the substituent at the silicon atom. This is apparently due to the existence of a p π— d π interaction between the heterocyclic π-system and the d-orbitals of silicon.

Tris(difluoro and trifluorobutane-2,4-dionato) gallium(III) and indium(III) complexes

Eight tris(β-diketonate)gallium(III) and seven tris(β-diketonate)-indium(III) complexes M(RCOCH-COR′) 3, with R′being difluoromethyl and trifluoromethyl substituents and R′ being methyl, phenyl, aryl, 2′-naphthyl and 2′-thienyl substituents have been studied by nuclear magnetic resonance spectroscopy. The complexes are all nonrigid (fluxional) and their 19F NMR spectra show four resonances in the nonexchanging regions due to cis and trans isomers. A variable low temperature study of these complexes was done for the gallium chelates and activation parameters are calculated. The indium complexes all have nonexchanging regions below −100°C. The 13C NMR data on the complexes are also reported.

The synthesis and molecular structures of two cyclobutadienecobalt complexes formed by the reaction between π-cyclopentadienyldicarbonylcobalt and phenyl-2-thienylacetylene

The reaction between h 5-cyclopentadienyldicarbonylcobalt and phenyl-2-thienylacetylene in refluxing xylene has been found to produce 78% yield of ( h 5-cyclopentadienyl)( h 4-diphenyldi-2-thienylcyclobutadiene) cobalt, as well as lesser amounts of a cyclotrimerization product, triphenyltri-2-thienylbenzene, and three isomeric cyclopentadienone cobalt complexes. A single crystal X-ray structural study intended to confirm the disposition of the phenyl and thienyl substituents of the cyclobutadiene ring in the first compound was carried out. The results are inconclusive since there is disorder of these groups in the crystalline lattice. The most likely model involves a mixture of cis and trans isomers plus phenylthienyl disorder. The atoms of the ( h 5-C 5H 5)Co(C 4) moiety are well behaved crystallographically and have molecular parameters which are within accepted values of recent determinations not plagued by disorder or uncertainty of isomeric purity. A minor biproduct, resulting from the apparent coreaction of phenyl-2-thienyl-acetylene and diphenyldiacetylene with h 5-cyclopentadienyldicarbonylcobalt, has also been identified by spectral and X-ray diffraction techniques as the novel complex bis [( h 5-cyclopentadienyl)( h 4- trans-diphenyl-2-thienylcyclobutadienyl)-cobalt]. The crystallographic study of this compound also revealed disorder in the thienyl groups but it is not as severe as that found for the major product.

S-Triazines. Part V. Synthesis and hydrolytic stability of 2,4-dihalogeno-6-heteroaryl-s-triazines

The first and second hydrolysis rate coefficients for the title compounds are discussed in terms of variation of the heteroaryl substituent (substituted phenyl, furyl, pyrrolyl, or thienyl) and of the halogen substituents (X = F, Cl, I, or CCl3). Electron-withdrawing substituents in the aryl rings enhance the rate coefficients, which are linearly related to the pKa values of the analogous dioxo-products (III) for phenyl, thienyl, or pyrrolyl substituents. Evidence is presented to show that the rate-determining step in the hydrolysis is nucleophilic attack on the triazine rather than carbon–halogen bond rupture.

Crystal and molecular structure of 4,7-di-(2-thienyl)-4,5,6,7-tetrahydrobenzo[b]thiophen

The crystal structure of the title compound, the ‘pentamer’ fraction of the acid-catalysed polymerisation of thiophen, has been determined by direct methods from three-dimensional photographic data. The crystals are monoclinic, space group, P21/c(C52h), with a= 14·13, b= 7·68, c= 13·78 A and β= 104·1°. The disordered structure has been refined by least-squares methods to R 0·111 over 2307 independent reflexions. The cyclohexene ring adopts the half-chair conformation with the thienyl substituents in a cis-configuration.