Bis-Thiourea Bearing Aryl and Amino Acids Side Chains and Their Antibacterial Activities

Abstract

A series of symmetrical 1,3-bis thiourea 1a–e and 1,4-bis thiourea derivatives 2a–e have been successfully synthesized from the reactions of amines with 3-acetylbenzoyl isothiocyanate and 4-acetylbenzoyl isothiocyanate, respectively. All the synthesized compounds were characterized by FT-IR spectroscopy and ¹H and ¹³C NMR spectroscopy. The compounds were screened for their antibacterial activity by turbidimetric method using gram-negative bacteria (E. coli ATCC 8739) using turbidimetric method. The newly synthesized bis-thiourea derivatives bearing aryl side chains showed good antibacterial activity against E. coli. The effect of the molecular structure of the synthesized compounds on the antibacterial activity is discussed.     

Synthesis of 6-(arylthio)- and 6-[(arylmethyl)thio] -1,2,4,5-tetrazin-3-amines and n-phenyl- and n-(phenylmethyl)-1,2,4,5-tetrazine-3,6-diamines as potential antimalarial agents

Alkylation of tetrahydro-1,2,4,5-tetrazine-3,6-dithione with iodomethane and 1,2-dichloro-4-(chloromethyl)benzene, respectively (Scheme 1, 4 ) followed by oxidation afforded 3,6-bis(methylthio)- and 3,6-bis[[(3,4-dichlorophenyl)methyl]thio]-1,2,4,5-tetrazines ( 6, 15 ). The reaction of 15 with amines provided the 6-[(arylmethyl)thio]-1,2,4,5-tetrazin-3-amines ( 16) while sequential displacement of both methylthio groups in 6 afforded the tetrazine-diamines 8 and 10 . Hydrolysis of N,N-dimethyl-6-(methylthio)-1,2,4,5-tetrazin-3-amine ( 11 ) with potassium hydroxide afforded the tetrazin-3-ol ( 12 ) which was chlorinated and then treated with 4-chlorobenzenethiol to provide 13 . The target 6-substituted-1,2,4,5-tetrazin-3-amines displayed negligible antimalarial activity.     

Facile synthesis of 6-organyl-4-(trifluoromethyl)pyridin-2(1H)-ones and their polyfluoroalkyl-containing analogs

The three-component cyclization of 3-polyfluoroalkyl-3-oxopropanoates and methyl ketones with ammonium acetate affords 6-organyl-4-(polyfluoroalkyl)pyridin-2(1H)-ones (organyl is alkyl, aryl, or hetaryl). The synthesized pyridones were evaluated for antifungal, antibacterial, and analgesic activity.

     

The role of palladium catalyst and base in stereoselective transformations of (E)-2-chlorovinylsulfides

Stereoselective transformations of 2-chlorovinylsulfides in the presence of soluble (t-BuOK) or insoluble (solid KOH or Cs₂CO₃/18-crown-6) base and palladium catalyst (dppb)Pd(OAc)₂ have been studied. Depending on the substrate or catalytic system, the reaction leads to the formation of (E)-1,2-bis[aryl(or arylmethyl)thio]ethenes and/or (E)-1,4-bis[aryl(or arylmethyl)thio]-1-buten-3-ynes in yields of up to 93%.     

3-aryl(alkyl)quinazoline-2,4(1<Emphasis Type="Italic">H</Emphasis>,3<Emphasis Type="Italic">H</Emphasis>)-diones and their alkyl derivatives

Two-stage reaction of methyl anthranilate with aryl(alkyl) isocyanates in keeping with the quantumchemical calculations and XRD analysis resulted in 3-aryl(alkyl)quinazoline-2,4(1H,3H)-diones that by treatment with alkyl halides, phenacyl bromides, esters and amides of chloroacetic acid were converted into the corresponding 1-alkyl derivatives.     

Synthesis and Reactivity of New Silylated Sulfur-Containing Heterocyles Through Thionation of Bis(Acylsilanes)

Abstract

The optimization of the synthesis of 2,6-bis(trialkylsilyl)4H-thiopyranes and some aspects of the reactivity of the corresponding lithium salts with alkyl halides and benzaldehyde are presented.     

Synthesis and properties of z-1,3-bis-(aryl)-4-bromo-2-buten-1-ones

Bromination of 1,3-bis(aryl)-2-buten-1-ones by N-bromosuccinimide in anhydrous carbon tetrachloride gives Z-1,3-bis(aryl)-4-bromo-2-buten-1-ones. The effect of the nature of substituent in the benzene ring on the course of a reaction with nucleophiles has been studied. Heating an alcohol solution of these ketones (Ar = 4-MeOC₆H₄, 4-ClC₆H₄) in the presence of acid or in the presence of base (Ar = Ph) gave 2,4-bis(aryl)furans. Treatment of 1,3-bis(aryl)-4-bromo-2-buten-1-ones with thioacetamide gave 2,4-bis(aryl)thiophenes. The oxidation of the halo-substituted dypnones with H₂O₂/NaOH gave (3-bromomethyl-3-aryl-2-oxiranyl)(aryl)methanones. The reaction of halo-substituted dypnones with aryl hydrazines gave 1,3,5-triaryl-1,6-dihydropyridazines or 1,3,5-triarylpyridazinium bromides depending on the structure of the reagents.     

Syntheses of various 5-(3′-substituted phenyl)uracils

The Suzuki Pd(0)-catalysed coupling between arylboronic acids and aryl bromides or iodides in weakly alkaline medium has been used for the preparation of 5-(3′-chlorophenyl)-, 5-(3′-iodophenyl)-, 5-(3′-aminophenyl)-, 5-(3′-azidophenyl)-, 5-(3′-methylthiophenyl)- and 5-(3′-styryl)-substituted 2,4-di-t-butoxypyrimidines. In the coupling between 2,4 di-t-butoxy-5-pyrimidineboronic acid and the six different aryl halides that were used as coupling partners, only 1-azido-3-bromobenzene did not give satisfactory yields, 18%. The other five aryl halides gave the desired 5-(3′-substituted phenyl)-2,4-di-r-butoxypyrimidines in 41–92% yield. Dealkylation of these five 5-(3′-substituted phenyl)-2,4-di-t-butoxypyrimidines in 2.5M hydrochloric acid gave the corresponding 5-(bromoaryl)uracils in almost quantitative yields. 5-(3′-Azidophenyl)uracil was prepared in 43% yield directly from 5-(3′-aminophenyl)-2,4-di-r-butoxypyrimidine.     

Parallel Synthesis of Novel 3-Substituted 1-Ethyl-6-methylpyrimido[4,5-c]pyridazine-5,7(1H,6H)-dione Analogs

A library of novel 1H-pyrimido[4,5-c]pyridazine-5,7-dione analogs was prepared in a parallel fashion via the cyclization of 6-(1-ethylhydrazinyl)-3-methylpyrimidine-2,4(1H,3H)-dione (4) with α-bromoketones and was then isolated by a two-step purification method with >90% purity. Both the library synthesis and purification method proved suitable for analogs with a high diversity of substitution at the 3-position including various alkyl, aryl, and heteroaryl groups.     

Enhancing performance of α-diiminonickel precatalyst for ethylene polymerization by substitution with the 2,4-bis(4,4'-dimethoxybenzhydryl)-6-methylphenyl group

High activities in ethylene polymerization predetermine α-diiminonickel precatalysts for potential industrial applications. In our study, we have synthesized and characterized a series of unsymmetrical 1-(2,4-bis(4,4′-dimethoxybenzhydryl)-6-MeC₆H₂N)-2-arylimino-acenaphthylene nickel(II) halides. The single-crystal X-ray diffraction study of representative compounds reveals distorted tetrahedral geometry. On activation with either Me₂AlCl or modified methylaluminoxane, these nickel complexes exhibit high activities of the order of 10⁶ g of PE (mol of Ni)⁻¹ h⁻¹ and produce polyethylene of generic application characterized by high molecular weight, narrow molecular weight distribution, and moderate degree of branching. The substituents at the ligands affect the catalytic performance of the nickel complexes and tune the microstructure of the resultant polyethylene.     

Symmetrical and Unsymmetrical Coupling of Alkyl Halides Mediated by Grignard Reaction

A simple method for extending the carbon chain via the coupling of alkyl or aryl halides has been developed. The versatility of this reaction has been demonstrated by symmetrical and unsymmetrical coupling of alkyl, alkenyl or alkynyl halides.     

Synthesis and antimalarial properties of 2,4-diamino-6-[(aryl)thio,sulfinyl, and sulfonyl]pyrido[3,2-d]pyrimidines

The synthesis and antimalarial activity of a series of 2,4-diamino-6-[(aryl)thio, sulfinyl and sulfonyl]pyrido-[3,2-d]pyrimidines is described. Nitration of 2,6-dichloropyridine provided the 3-nitro derivative which was converted to 6-chloro-3-nitro-2-pyridinecarbonitrile (V) with cuprous cyanide. Condensation of an aryl thiol with V gave the 6-arylthiopyridines VI which were reduced with iron in hydrochloric acid and condensed with chloroformamidine to give the 6-arylthiopyrido[3,2-d]pyrimidin-2,4-diamines X. Alternatively V was reduced to the amine VIII condensed with chloroformamidine and the resulting 6-chloropyrido[3,2-d]pyrimidine (IX) was treated with an arylthiol. Oxidation of X provided sulfinyl and sulfonyl analogs.     

Synthesis and Characterization of New Schiff Bases 2-(2-(2-(Aryl)Methyleneamino)Phenylthio) Ethylthio)-N-((aryl)Methylene)Benzeneamine

A series of Schiff bases containing four to six coordination sites N₂S₂ X₂(X = O,N) 2-(2-(2-(aryl)methyleneamino)phenylthio)ethylthio)-N-((aryl)methylene)benzeneamine (2c–f) were prepared from the reaction of 1,2-di(2-aminophenylthio)ethane (1) with aromatic aldehydes. All compounds were characterized by means IR, mass, ¹H and ¹³C NMR spectroscopy, and elemental analysis, and in the case of 2b with a single crystal X-ray diffraction. The X-ray crystal structure of 2b showed that the resonance occurs between aromatic rings, through the C=N bonds of the molecule.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Chemical transformations of 6-[(1-methyl-4-nitro-5-imidazolyl)-thio]purine (azathioprine)

The chemical transformations of 6-[(1-methyl-4-nitro-5-imidazolyl)thio]purine (azathiopurine) —hydrogenation, acetylation, alkylation by lower alkyl halides at positions 7 and 9 of the purine ring, hydrolytic cleavage at the C₍₆₎–S and S–C₍₅₎ bonds— were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 372–379, March, 2000.     

Synthesis and Molecular Structure of New Macro Acyclic Mannich Derivatives: Symmetrical and Unsymmetrical 2-[(E)-(Benzylideneamino)(aryl)methyl]cyclododecanone

Abstract

In an effort to provide a green synthetic route for heterocyclic scaffolds, new macro analogs of acyclic Mannich derivatives have been synthesized in good yields in a one-pot, efficient fashion. The acyclic symmetrical and unsymmetrical 2-[(E)-(benzylideneamino)(aryl)methyl]cyclododecanones have been synthesized by condensation of cyclododecanone, aromatic aldehyde, and ammonium acetate in ethanolic media. By infrared, NMR, and mass spectral analyses, their structures were determined. Examination of crystal structure of a p-Cl and o-Br analogs reveals the minimum energy [3333] square conformation of cyclododecanone ring. In the crystal, molecules aggregate in dimeric subunits formed by C-Cl … π and C-H..π interactions. The reported one-pot, multichain reaction of macrocycles is the first synthetic attempt of acyclic compounds in this type of Mannich reaction involving ketones containing active methylene groups.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Efficient Copper(I)‐Catalyzed S‐Arylation of KSCN with Aryl Halides in PEG‐400

A simple and efficient protocol for CuI‐catalyzed C? S bond formation of aryl halides with KSCN to symmetrical diaryl sulfides was reported in PEG‐400 without any other additives. A variety of aryl halides were converted to the corresponding diaryl sulfides in good to excellent yields. The present procedure tolerated a variety of functional groups and the steric hindrance of ortho‐substituents on aryl halides did not affect the outcome.     

Palladium‐Catalyzed Heteroarylation and Concomitant ortho‐Alkylation of Aryl Iodides

Three‐component couplings were achieved from common aryl halides, alkyl halides, and heteroarenes under palladium and norbornene co‐catalysis. The reaction forges hindered aryl–heteroaryl bonds and introduces ortho‐alkyl groups to aryl rings. Various heterocycles such as oxazoles, thiazoles and thiophenes underwent efficient coupling. The heteroarenes were deprotonated in situ by bases without the assistance of palladium catalysts.     

Asymmetric oxidation of sulfides catalyzed by (R)-6,6'-dibromo-BINOL derived titanium complex

Abstract

An efficient asymmetric oxidation of sulfides was achieved using (R)-6,6'-dibromo-BINOL as chiral ligand in combination with Ti(OⁱPr)₄ using 70% aqueous tertiary butyl hydroperoxide as oxidant. The resulting sulfoxides had high enantiopurities and good yields. A range of aryl alkyl and aryl benzyl sulfides were oxidized to the corresponding sulfoxides with 78–95% ee in 72–80% yields.     

Synthesis of trichloromethylpyrimidines and trichloromethylpyrimido [4,5-<Emphasis Type="Italic">d</Emphasis>]pyrimidines from alkyl 2-(diaminomethylidene)-3-oxobutyrates and trichloroacetonitrile

Heterocyclization of alkyl 2-(diaminomethylidene)-3-oxobutyrates with trichloroacetonitrile yields alkyl 4-mino-6-methyl-2-trichloromethylpyrimidine-5-carboxylates. The latter compounds react with aryl isocyanates to produce the corresponding pyrimidinylureas, which undergo cyclization to 3-aryl-5-methyl-7-trichloromethylpyrimido[4,5- d]pyrimidine-2,4(1H,3H)-diones under the action of MeONa in MeOH.     

A simple and efficient approach for the synthesis of a novel class aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives via intramolecular nucleophilic substitution reaction

In this study, we synthesized a new series of substituted aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives (6-24) in yields ranging from 42 to 70% with an interesting mechanism that involves internal nucleophilic substitution followed by an S_N2-type nucleophilic substitution. First, 1-(4-chlorophenyl)-2-((5-methyl-1,3,4-thiadiazol-2-yl)thio)ethanone (3) was synthesized from the reaction of 5-methyl-1,3,4-thiadiazole-2-thiol (1) with 2-bromo-1-(4-chlorophenyl)ethanone (2) in the presence of potassium hydroxide. Then, 1-(4-chlorophenyl)-2-((5-methyl-1,3,4-thiadiazol-2-yl)thio)ethanol (4) was synthesized by a reduction reaction of this compound using NaBH₄. Finally, 5-methyl-3-alkyl-1,3,4-thiadiazol-2(3H)-one derivatives (6-24), which are the target compounds, were synthesized from the reaction of this compound (4), which is a secondary alcohol with various alkyl halides (5a-n) in the presence of sodium hydride (NaH). This study presents an interesting reaction mechanism related to the synthesis of aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives that is not recorded in the literature.