Preparation of 3‐aminoalkylbenzo[b]thiophenes

We report an efficient entry into substituted 3‐(ω‐aminoalkyl)‐benzo[b]thiophenes that allows rapid generation of structural diversity. Alkylation of α,ω‐dihaloketones with thiophenols followed by acid‐catalysed cyclisation led to an efficient synthesis of 3‐(ω‐aminoalkyl)benzo[b]thiophenes. 2‐Carboethoxy derivatives were prepared using a directed ortho‐metallation approach. These derivatives were readily converted into the corresponding amines.     

Synthesis and Crystal Structure of [1‐(η5‐9‐Fluorenyl)‐2‐(η5‐1‐indenyl)ethane]hafnium Dimethyl

The synthesis and characterization of the unsymmetric hafnium dialkyl [1‐(η⁵‐9‐fluorenyl)‐2‐(η⁵‐1‐indenyl)ethane]HfCl₂ ( 2 ) and corresponding dimethyl complex [1‐(η⁵‐9‐fluorenyl)‐2‐(η⁵‐1‐indenyl)ethane]Hf(CH₃)₂ ( 3 ) is described. The dialkyl hafnocene ( 3 ) crystallizes in monoclinic space group P2₁/c (No. 14) with a = 9.458(8), b = 8.541(8), c = 23.733(11) Å, β = 93.16(5) deg., V = 1914(3) ų, Z = 4. Further on, complex 3 was activated with methylaluminiumoxane (MAO) and utilized as a catalyst in ethene polymerization.     

Synthesis of α‐[5‐(5‐amino‐1,3,4‐thiadiazol‐2‐yl)‐2‐imidazolylthio]acetic acids

The paper describes synthesis and antituberculosis activity of α‐[5‐(5‐amino‐1,3,4‐thiadiazol‐2‐yl)‐imidazol‐2‐ylthio]acetic acids ( 5a,b ). The compounds were tested against Mycobacterium tuberculosis strain H37Rv in comparison to rifampicin. Compounds exhibited low activity (MIC ≤ 6.25 μg/ml, % inhibition ≥ 24).     

Polar aspects of intramolecular interactions in 2‐amino‐5‐nitro‐4‐methylpyridines and 2‐amino‐3‐nitro‐4‐methylpyridines

The dipole moments of twelve 2‐N‐substituted amino‐5‐nitro‐4‐methylpyridines ( I‐XII ) and three 2‐N‐substituted amino‐3‐nitro‐4‐methylpyridines ( XIII‐XV ) were determined in benzene. The polar aspects of intramolecular charge‐transfer and intramolecular hydrogen bonding were discussed. The interaction dipole moments, μ_int, were calculated for 2‐N‐alkyl(or aryl)amino‐5‐nitro‐4‐methylpyridines. Increased alkylation of amino nitrogen brought about an intensified push‐pull interaction between the amino and nitro groups. The solvent effects on the dipole moments of 2‐N‐methylamino‐5‐nitro‐4‐methyl‐( I ), 2‐N,N‐dimethylamino‐5‐nitro‐4‐methyl‐ ( II ) and 2‐N‐methylamino‐3‐nitro‐4‐methylpyridines ( XIII ) were different. Specific hydrogen bond solute‐solvent interactions increased the charge‐transfer effect in I , but it did not disrupt the intramolecular hydrogen bond in XIII.     

Bis[N‐(4‐nitrophenyl)thiobenzamidato]mercury(II)

The molecule of the title compound, [Hg(C₁₃H₉N₂O₂S)₂], has approximate twofold rotation symmetry, with the Hg atom in an essentially linear two‐coordinate HgS₂ environment supported by secondary π interactions with the nitrophenyl rings of both ligands. The ligands are in the imine–thiolate rather than the amine–thione tautomeric form.     

(E)‐3‐(Benzo[b]thiophen‐2‐yl)‐2‐(3,4,5‐trimethoxyphenyl)acrylonitrile and (Z)‐3‐(benzo[b]thiophen‐2‐yl)‐2‐(3,4‐dimethoxyphenyl)acrylonitrile

The title compounds, C₂₀H₁₇NO₃S, (I), and C₁₉H₁₅NO₂S, (II), were prepared by the reaction of benzo[b]thiophene‐2‐carbaldehyde with (3,4,5‐trimethoxyphenyl)acetonitrile and (3,4‐dimethoxyphenyl)acetonitrile, respectively, in the presence of methanolic potassium hydroxide. In (I), the C=C bond linking the benzo[b]thiophene and the 3,4,5‐trimethoxyphenyl units has E geometry, with dihedral angles between the plane of the bridging unit and the planes of the two adjacent ring systems of 5.2 (3) and 13.1 (2)°, respectively. However, in (II), the C=C bond has Z geometry, with dihedral angles between the plane of the bridging unit and the planes of the adjacent benzo[b]thiophene and 3,4‐dimethoxyphenyl units of 4.84 (17) and 76.09 (7)°, respectively. There are no significant intermolecular hydrogen‐bonding interactions in the packing of (I) and (II). The packing is essentially stabilized via van der Waals forces.     

The synthesis and transformations of 2‐[2‐ethoxycarbonyl‐2‐(2‐pyridinyl)ethenyl]amino‐3‐dimethylaminopropenoates. the synthesis of substituted β‐amino‐α,β‐didehydro‐a‐amino acid derivatives

Alkyl (Z)‐2‐[(E)‐2‐ethoxycarbonyl‐2‐(2‐pyridinyl)ethenyl]amino‐3‐dimethylaminopropenoates 7 and 8 were prepared from ethyl 2‐pyridinylacetate (1) in two steps. Substitution of the dimethylamino group with alkyl‐, aryl‐, or heteroarylamines afforded the corresponding β‐alkyl‐ 22–24 , β‐aryl‐ 25–35 , and β‐herteroaryl‐amino‐α,β‐didehydro‐α‐amino acid 36 and 37 derivatives, intermediates for further preparation of various heterocyclic systems. The orientation around both double bonds were determined by various nmr techniques.     

[2‐(2‐{Bis[2‐(1H‐imidazol‐2‐ylmethyleneamino)ethyl]amino}ethyliminomethyl)imidazolido]cobalt(III) bis(tetrafluoridoborate) monohydrate

The title compound, [Co(C₁₈H₂₃N₁₀)](BF₄)₂·H₂O, is the result of complexing a Co cation (initially in a Co^II state) with tris[2‐(1H‐imidazol‐2‐ylmethyleneamino)ethyl]amine (L), obtained by a condensation process involving imidazole‐2‐carbaldehyde and tris(2‐aminoethyl)amine. Both the Co cation and the ligand were modified in the synthesis process, the cation via oxidation to Co^III, and the ligand via deprotonation to convert it into the 2‐(2‐{bis[2‐(1H‐imidazol‐2‐ylmethyleneamino)ethyl]amino}ethyliminomethyl)imidazolide anion (L⁻). The ligand chelates the metal centre in a hexadentate fashion, forming a slightly distorted octahedral CoN₆ chromophore. Packing is governed by N—H...N hydrogen bonds defining zigzag chains. A similar structure in the literature is discussed, and the wrong assignment of the oxidation state, given therein to the Co cation, is corrected.     

1‐(4‐Chloro­phenyl)‐2‐methyl‐4‐nitro‐5‐(1‐piperidyl)‐1H‐imidazole

The only specific inter­actions that influence the crystal packing of the title compound, C₁₅H₁₇ClN₄O₂, are weak C—H⋯N and C—H⋯Cl hydrogen bonds, even though there is a possibility of, for example, π–π stacking or halogen bonding. The dihedral angle between the mean planes of the imidazole and benzene rings is 59.82 (5)°. The length of the C—N bond connecting the imidazole and piperidine fragments is correlated with the degree of pyramidalization of the piperidine N atom.     

A facile one‐pot synthesis of thiazo[2′,3′:2,1] imidazo[4,5‐b]pyrane; thiazo[2′,3′:2,1]imidazo [4,5,b]pyridine; imidazo[2,1‐b]thiazole and 2‐(2‐amino‐4‐methylthiazol‐5‐yl)‐1‐bromo‐1,2‐ethanedione‐1‐arylhydrazones

Thiazole 1 , when reacted with chloroacetyl chloride, afforded N‐(5‐acetyl‐4‐methylthiazol‐2‐yl) chloroacetamide 2 . It has been found that compound 2 reacted with α‐cyanocinnamonitrile derivatives 6a–c to afford reaction products 8a–c . Also, compound 2 coupled smoothly with benzenediazonium chloride afforded the phenylhydrazone 14 . Coupling of the sulfonium bromide 17 with diazotized aromatic amines or N‐nitrosoacetanilides afforded the arylhydrazones 20a,b . Treatment of 16 with 2‐cyanoethanethioamide afforded [4‐(2‐amino‐4‐methylthiazol‐5‐yl) thiazol‐2‐yl] acetonitrile 22 . © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:362–369, 2000     

6‐(2‐Fluorobenzylidene)‐2‐[1‐(2‐fluoro‐4‐biphenyl)ethyl]thiazolo[3,2‐b][1,2,4]triazol‐5(6H)‐one

The title compound, C₂₅H₁₇F₂N₃OS, was synthesized from 6‐(benzyl­idene)­thia­zolo­[3,2‐b][1,2,4]triazol‐5(6H)‐one. The fused thia­zolo­[3,2‐b][1,2,4]triazole system is essentially planar, and bifurcated C—H⋯O, C—H⋯N and C—H⋯F interactions are present between mol­ecules.     

5‐Acetyl‐2‐amino‐6‐methyl‐4‐(3‐nitrophenyl)‐4H‐pyran‐3‐carbonitrile and 2‐amino‐5‐ethoxycarbonyl‐6‐methyl‐4‐(3‐nitrophenyl)‐4H‐pyrano‐3‐carbonitrile

The structures of the title compounds, C₁₅H₁₃N₃O₄, (I), and C₁₆H₁₅N₃O₅ [IUPAC name: ethyl 6‐amino‐5‐cyano‐2‐methyl‐4‐(3‐nitro­phenyl)‐4H‐pyrano‐3‐carboxyl­ate], (II), are very similar, with the heterocyclic rings adopting boat conformations. The pseudo‐axial m‐nitro­phenyl substituents are rotated by 84.0 (1) and 98.7 (1)° in (I) and (II), respectively, with respect to the four coplanar atoms of the boat. The dihedral angles between the phenyl rings and nitro groups are 12.1 (2) and 8.4 (2)° in (I) and (II), respectively. The two compounds have similar patterns of intermolecular N—H?O and N—H?N hydrogen bonding, which link mol­ecules into infinite tapes along b .     

3,5‐Dimethyl‐4‐[(E)‐(2‐nitrophenyl)diazenyl]‐1‐(2,3,4,5,6‐pentafluorophenyl)‐1H‐pyrazole

The title compound, C₁₇H₁₀F₅N₅O₂, is described and compared with its 4‐nitrophenyl isomer [Bustos, Sánchez, Schott, Alvarez‐Thon & Fuentealba (2007). Acta Cryst. E 63 , o1138–o1139]. The title molecule presents its nitro group split into two rotationally disordered components, which in conjunction with the rotation of the `unclamped' rings constitute the main molecular differences. Packing is directed by a head‐to‐tail type `I' C—F...F—C interaction, generating double‐chain strips running along [100]. These substructures are interlinked by a variety of weak F...F, O...F, F...π and O...π interactions.     

Two derivatives of 5‐amino­tetrazole: 5‐amino‐1‐phenyl­tetrazole and 5‐amino‐1‐(1‐naphthyl)­tetrazole

In the mol­ecules of 5‐amino‐1‐phenyl­tetrazole, C₇H₇N₅, (I), and 5‐amino‐1‐(1‐naphthyl)­tetrazole, C₁₁H₉N₅, (II), the tetrazole rings and aryl fragments are not coplanar; corresponding dihedral angles are 50.58 (5) and 45.19 (7)° for the two independent mol­ecules of (I), and 64.14 (5)° for (II). Intermolecular N—H⋯N hydrogen bonds between the amino groups and tetrazole N atoms are primarily responsible for formation of two‐dimensional networks extending parallel to the bc plane in both compounds. The presence of the amino group has a distinct effect on the geometry of the tetrazole rings in each case.     

Synthesis of new methylated thieno[2,3‐a] and [3,2‐b]carbazoles by reductive cyclization of 6‐(2′‐Nitrophenyl)benzo[b]thiophenes obtained by palladium‐catalyzed cross‐coupling isabel

The synthesis of new methylated thieno[2,3‐a] and [3,2‐b]carbazoles (5) (R=H) was achieved by a palladium‐catalyzed cross‐coupling, intramolecular reductive cyclization sequence of reactions. The cyclization precursors 6‐(2′‐nitrophenyl)benzo[b]thiophenes (3) were obtained by Suzuki cross‐coupling of 6‐boronated methylbenzo[b]thiophenes intermediates (2) with 2‐bromo or iodonitrobenzene. The boronated intermediates (2) were prepared via bromine‐lithium exchange followed by boron transmetalation and coupled in situ using Pd(OAc)₂ giving thus a “one‐pot” three steps reaction from the 6‐bromobenzo[b]thio‐phenes (1) to the cyclization precursors (3) . In the reductive cyclization step, N‐ethylthienocarbazoles (5) (R=Et) were also obtained. Several experiments have been made varying the amount of triethylphosphite and the time of reaction, to avoid their formation.     

Bis[1‐(2‐hydroxyethyl)‐4,10‐diazapyrazolo[4,3‐b]fluoren‐5(1H)‐one thiosemicarbazonato]zinc(II) dimethylformamide trisolvate monohydrate

In the title Schiff base complex, [Zn(C₁₅H₁₂N₇OS)₂]·3C₃H₇NO·H₂O, each Zn^II atom is six‐coordinated in a distorted octahedral environment by two ligands acting in a tridentate chelating mode through two N atoms and one S atom. The coordination mode of the ligand is nearly planar. There are three dimethylformamide molecules and one water molecule solvating the complex. The coordination behavior of the ligand is compared with that of related ligands in similar complexes.     

Synthesis of 6‐(2‐hydroxybenzoyl)pyrazolo[1,5‐a]pyrimidines by reaction of 5‐amino‐1h‐pyrazoles and 3‐formylchromone

Reaction of 3‐formylchromone ( 1 ) with 5‐amino‐1H‐pyrazoles ( 2 ) in ethanol, afforded 6‐(2‐hydroxy‐benzoyl)pyrazolo[1,5‐a]pyrimidines ( 3a‐g ) in good yields. The structures and the regiospecificity of the reaction were established by nmr measurements and X‐ray analysis, in which soft intermolecular hydrogen‐bonded networks were found.     

1‐(4‐Chloro­phenyl­sulfanyl)‐2‐nitro‐4‐(tri­fluoro­methyl)­benzene and 1‐(4‐chloro­phenyl­sulfanyl)‐4‐nitro‐2‐(tri­fluoro­methyl)­benzene

Two chemical isomers of 3‐nitro­benzotrifluoride, namely 1‐(4‐chloro­phenyl­sulfanyl)‐2‐nitro‐4‐(tri­fluoro­methyl)­benzene, C₁₃H₇ClF₃NO₂S, (I), and 1‐(4‐chloro­phenyl­sulfanyl)‐4‐nitro‐2‐(tri­fluoro­methyl)­benzene, C₁₃H₇ClF₃NO₂S, (II), have been prepared and their crystal structures determined with the specific purpose of forming a cocrystal of the two. The two compounds display a similar conformation, with dihedral angles between the benzene rings of 83.1 (1) and 76.2 (1)°, respectively, but (I) packs in P while (II) packs in P2₁/c, with C—H⋯O interactions. No cocrystal could be formed, and it is suggested that the C—H⋯O associations in (II) prevent intermolecular mixing and promote phase separation.     

Synthesis of 4H‐indeno[1,2‐b]thiophenes, 8H‐indeno[2,1‐b]‐thiophenes and 8H‐indeno[2,1‐b]furans having acrylic acid unit

Treatment of methyl propiolate and 2‐(thiophen‐2‐yl)benzaldehyde, 2‐(thiophen‐3‐yl)benzaldehyde or 2‐(furan‐3‐yl)benzaldehyde with tetrabutylammonium iodide/zirconium (IV) chloride or treatment of methyl acrylate and the same aldehydes with 1,4‐diazabicyclo[2,2,2]octane and triethanolamine induce an aldol‐type reaction to furnish Baylis‐Hillman adducts β‐iodo‐α‐(hydroxymethyl)acrylates or α‐(hydroxy‐methyl)acrylates, respectively. These can be used for the preparation of indenothiophenes and indenofurans having acrylic acid unit by intramolecular Friedel‐Crafts reaction with sulfuric acid in tetrachloromethane.     

Synthesis of substituted 3‐(5‐amino‐[1,3,4]thiadiazol‐2‐yl)‐2H‐pyrano[2,3‐c]pyridin‐2‐ones

An efficient two‐step synthesis of novel 3‐(5‐amino‐[1,3,4]thiadiazol‐2‐yl)‐2H‐pyrano[2,3‐c]pyridine‐2‐ones was developed. In the first step, a new 2H‐pyrano[2,3‐c]pyridine‐3‐carboxamide 5 was prepared by Knoevenagel condensation of pyridoxal hydrochloride with cyanoacetamide. In the second step, the reaction of carboxamide 5 with a series of N⁴‐substituted thiosemicarbazides yielded a library of 35 dis crete compounds 8 {1–35} in high yields. The intermolecular recyclization mechanism leading to these products is discussed.