Synthesis of novel N‐alkyl/aryl‐N′‐(4‐arylthiazol‐2‐yl)‐N″‐xylosyl guanidines

The reaction of 2,3,4‐tri‐O‐acetyl‐β‐D‐xylopyranosyl isothiocyanate ( 1 ) and 2‐amino‐4‐arylthiazoles ( 2 ) gave xylosylthioureas 3 . These thiourea derivatives reacted with alkyl/aryl amine in the presence of HgCl₂ to give a new series of N‐alkyl/aryl‐N″‐(4‐arylthiazol‐2‐yl)‐N″‐xylosyl guanidines 4 . Some of the synthesized guanidines were screened for their biological activity. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:688–694, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20379     

Microwave‐assisted synthesis of some 1,2,4‐triazol‐5‐one derivatives

A series of 3‐alkyl(aryl)‐4‐(p‐hydroxy‐phenyl)‐4,5‐dihydro‐1H‐1,2,4‐triazol‐5‐ones 2 were obtained from the reaction of alkyl (aryl) ester ethoxycarbonyl hydrazones 1 with p‐hydroxy aniline. The reaction of 1 with 1,4‐diamino benzene (1:1) to afford 3‐alkyl(aryl)‐4‐(p‐aminophenyl)‐4,5‐dihydro‐1H‐1,2,4‐triazol‐5‐ones 3 . The reaction of 3 with benzaldehyde gave 3‐alkyl(aryl)‐4‐(4′‐benzilidenamino)‐4,5‐dihydro‐1H‐1,2,4‐triazol‐5‐ones 4 . All of the above reactions occurred under microwave heating and conventional methods. Their structures were confirmed by ¹H NMR, ¹³C NMR, IR, and elemental analyses. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:38–42, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20381     

Synthetic and mechanistic aspects of preparation of phosphinito‐ and phosphito‐mercuries

A >P O⁻ ( 1 ) type of anion has been used as an efficient synthetic precursor of four‐coordinated compounds: R₂P(O) Hg (O)PR₂ ( 5 ) and R₂P(O) Hg Bz ( 3 ) (R = alkoxy, alkyl, aryl). They were obtained in good yield. Bis(t‐butyl‐phenylphosphinito‐P)mercury (meso and rac) ( 5c,d ) selectively decomposed into 1,2‐di‐t‐butyl‐1,2‐diphenyldiphosphane 1,2‐dioxide (meso and rac) ( 6c,d) . Furthermore, some mechanistic aspects of the synthesis of mentioned compounds are elaborated.© 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:234–237, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20409     

Generation of Aryl(2‐lithiophenyl)methanone O‐Methyl Oximes and Their Use for the Synthesis of N‐(3‐Alkyl‐1‐aryl‐ or 1,3‐diaryl‐1H‐isoindol‐1‐yl)‐O‐methylhydroxylamines via the Reaction with Nitriles

An efficient two‐step procedure for the preparation of a new type of 1H‐isoindoles, i.e., N‐(3‐alkyl‐1‐aryl‐ or 1,3‐diaryl‐1H‐isoindol‐1‐yl)‐O‐methylhydroxylamines 5 , from readily available aryl(2‐bromophenyl)methanones 1 has been developed. Aryl(2‐bromophenyl)methanone O‐methyloximes 2 , derived from the corresponding ketones, were treated with BuLi in Et₂O at 0° to generate novel lithium compounds, aryl(2‐lithiophenyl)methanone O‐methyloximes 3 , which were allowed to react with nitriles to give the desired products 5 in moderate‐to‐fair yields.     

Original recyclization of S‐phenacyl derivatives of 4‐acylamino‐2‐mercapto‐1,3‐oxazoles and their analogues

Readily accessible acylamino(chloro)acetophenones, if treated with sodium rhodanide and α‐halogenocarbonyl compounds, provide 4‐acylamino‐5‐aryl‐2‐mercapto‐1,3‐oxazole derivatives which undergo recyclization on heating in polyphosphoric acid to give substituted 1,3‐thiazol‐2(3H)‐ones or 1,3‐thiazolidin‐2,4‐diones containing 2‐alkyl(aryl)‐5‐aryl‐1,3‐oxazol‐4‐yl residues at the N³ atom. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:432–437, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20317     

Synthesis and Antimicrobial Activity of N‐Aryl‐4‐(cyano/alkoxycarbonyl)‐5‐(pyridin‐3‐yl)‐1H/3H‐1,2,3‐triazole Derivatives

A convenient synthesis of a new series of N‐aryl‐5‐(pyridin‐3‐yl)‐1H/3H‐1,2,3‐triazole‐4‐carbonitriles and alkyl N‐aryl‐5‐(pyridin‐3‐yl)‐1H/3H‐1,2,3‐triazole‐4‐carboxylic acid esters is reported. The newly synthesized 5‐(pyridin‐3‐yl)‐1,2,3‐triazole derivatives are evaluated for their antibacterial and antifungal activity. Some of these triazole derivatives have exhibited moderate antimicrobial activity.     

Study of direction of cyclization of 1‐azolil‐4‐aryl/alkyl‐thiosemicarbazides

On a four series of 1‐azolil‐4‐aryl/alkyl‐thiosemicabazides, a study on the influence of azole moiety on the capability for intramolecular cyclization and its direction was carried out. It was found that for 4‐aryl/alkyl‐thiosemicabazides with triazole, imidazole, or pyrrole moiety at N‐1 nitrogen atom possible products were only s‐triazoles, both in alkaline and acidic medium. Successful dehydrocyclization of 1‐azolil‐4‐aryl/alkyl‐thiosemicarbazides leading to a thiadiazole has been documented only for a series of 1‐(4‐methyl‐1,2,3‐thiadiazol‐5‐yl‐carbonyl)‐4‐aryl/alkyl‐thiosemicarbazides. It can be speculative that the determination of pK_a value of oxygen atom of 1‐azolil‐4‐aryl/alkyl‐thiosemicarbazide can be a very valuable parameter in the prediction of the possibility of dehydrocyclization to form thiadiazole. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:521–532, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20643     

Synthesis and insecticidal activity of O‐aryl O‐(1,2,2,2‐tetrachloroethyl)phosphoramidothioates and their thiophosphoric hydrazides [1]

O‐Aryl O‐(1,2,2,2‐tetrachoroethyl)phos‐ phoramidothioates 3a–h and their thiophosphoric hydrazides 4a–e were synthesized by reactions of O‐aryl O‐(1,2,2,2‐tetrachoroethyl)thiophosphorochloridates 2 with amines and hydrazines, respectively. Their structures were characterized by elemental analysis IR ¹H NMR, ³¹P NMR, and MS. The O‐aryl O‐(1,2,2,2‐tetrachloroethyl)thiophosphoric hydrazides 4a–d (R²=H) can be transformed into 1,3,4,2‐oxadiazaphospholanes 5a–d by the reaction of triethylamine. The results of preliminary bioassays indicated that some of the title compounds have good insecticidal activities against nematodes (Meloidogyne spp.) and pea aphids. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 441–445, 1999     

An efficient FeCl3‐promoted O‐alkyl cleavage of esters to carboxylic acids

A reliable and practical procedure for FeCl₃‐promoted ester cleavage has been developed. Lewis acids including TiCl₄, ZnO and FeCl₃ etc. were investigated as promoters for O‐alkyl cleavage of carboxylic acid ester. Under optimal reaction conditions, FeCl₃ (1.5 equiv.) was found to possess the highest activity and efficiently enhanced dealkylation of aryl esters, alkyl esters and aromatic heterocyclic esters to give their corresponding carboxylic acids in 54–98% yield, the method provides a complementary access to dealkylation of ester under neutral condition. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and herbicidal activity of 2‐alkyl(aryl)‐3‐methylsulfonyl(sulfinyl)pyrano‐ [4,3‐c]pyrazol‐4(2H)‐ones

Useful oxidation reaction of 2‐alkyl(aryl)‐3‐methylthiopyrano[4,3‐c]pyrazol‐4(2H)‐ones, leading to either the corresponding sulfoxides or sulfones, using hydrogen peroxide and acetic acid in 1,2‐dichloroethane, is described. Bioassay results showed that the products have some herbicidal activity. © 2005 Wiley Periodicals, Inc. 16:255–258, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20067     

Facile synthesis of 2‐alkylthio‐5‐phenylmethylene‐4H‐imidazol‐4‐ones

2‐Alkylthio‐5‐phenylmethylidene‐4H‐imidazol‐4‐ones 4 were synthesized by S‐alkylation of 2‐thioxo‐3‐alkyl(aryl)‐4‐imidazolidinones 3 , which were obtained via cyclization of isothiocyanates 2 with aliphatic(aromatic) primary amines. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:348–351, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10160     

Crystal and molecular structures of atropisomeric N‐aryl‐1,2,3,4‐tetrahydro‐3,3‐dimethyl‐2,4‐quinolinediones

The crystal structures of N‐aryl‐1,2,3,4‐tetrahydro‐3,3‐dimethyl‐2,4‐quinolinediones bearing methoxy‐ ( 1 ), methyl‐ ( 2 ), and chloro‐ ( 3 ) substituents in 2′‐position of the phenyl ring have been determined by X‐ray crystal structure analysis. The heterocyclic ring in 1–3 adopts an envelope conformation, with the smallest ring puckering in the ortho‐chloro derivative 3 . The N‐aryl ring is almost perpendicular with respect to the quinoline‐2,4‐dione ring. The corresponding dihedral angle values are 83.2(1)°, 80.0(9)°, and 83.4(2)° in 1, 2 and 3 , respectively. The hydrogen bond of C H⋅⋅⋅O type joins the molecules of the ortho‐methoxy derivative 1 into dimers. The supramolecular structure also contains two C H⋅⋅⋅π interactions that link the hydrogen‐bonded dimers into sheets. In ortho‐methyl derivative 2 , one C H⋅⋅⋅π interaction generates infinite chains, whereas two C H⋅⋅⋅O hydrogen bonds and three C H⋅⋅⋅π interactions in the ortho‐chloro derivative 3 form three‐dimensional framework. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:325–331, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20436     

New cyclization of N‐hydroxyiminoyl chlorides with N‐alkyl ethynesulfonamides: Synthesis of 4‐alkyl‐3‐aryl‐4,5‐dihydro‐1,5,2,4‐oxathiadiazepine‐5,5‐diones

N‐Hydroxyiminoyl chlorides reacted with N‐alkyl ethynesulfonamides in the presence of triethylamine in CH₂Cl₂ to afford the 4‐alkyl‐3‐aryl‐4,5‐dihydro‐1,5,2,4‐oxathiadiazepine‐5,5‐diones (3) as the major products together with N‐alkyl‐3‐aryl‐5‐isoxazolesulfonamides (4). © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 461–464, 1999     

Polystyrene‐supported aluminum chloride: An efficient and recyclable green catalyst for one‐pot synthesis of 14‐aryl or alkyl‐14H‐dibenzo[a,j]xanthenes

A new, mild, and efficient method has been developed for the one‐pot synthesis of 14‐aryl or alkyl‐14H‐dibenzo[a,j]xanthenes by condensation of 2‐naphthol and aryl or alkyl aldehydes in the presence of a catalytic amount of cross‐linked polystyrene‐supported aluminum chloride (PS/AlCl₃) as an ecofriendly heterogeneous catalyst. This polymeric solid acid catalyst is stable and can be easily recovered and reused without appreciable change in its activity. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:51–54, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20655     

N‐functionalized azolin‐2‐ylidene‐palladium‐catalyzed heck reaction

Novel 1,3‐dialkylimidazolidinium, 1,3‐dialkyl‐3,4,5,6‐tetrahydropyrimidinium, and 1,3‐dialkyl‐1H‐4,5,6,7‐tetrahydrodiazepinium hexafluorophosphates ( 1a–c, 2a–c ) as N‐heterocyclic carbene precursors have been synthesized and characterized. The incorporation of saturated N‐heterocyclic carbenes into palladium precatalysts gives high‐catalyst activity in the Heck coupling of aryl bromide substrates in aqueous media. The complexes were generated in the presence of Pd(OAc)₂ by in situ deprotonation of 1,3‐dialkylazolinium salts 1, 2 . © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:82–86, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20415     

Synthesis and antimicrobial activity of 2‐(acyl or carboxyalkyl)‐3‐(H or alkyl or aryl)‐5 (or ‐6 or ‐8)‐monochloro, 7‐fluoro‐substituted‐4H‐1,4‐benzothiazines

A series of 2‐(acyl or carboxyalkyl)‐3‐(H or alkyl or aryl)‐5 (or ‐6 or ‐8)‐monochloro, 7‐fluoro‐substituted‐4H‐1,4‐benzothiazines 3a‐x were prepared to investigate their potential biological activity. In this work the 3a‐w structures are supported with physical and analytical data and the results of their in vitro antimicrobial activity against some strains Gram positive, Gram negative, and Fungi are reported. It was found that compounds 3a, 3d displayed interesting antibacterial activity, whereas compound 3f displayed interesting antifungal activity.     

Syntheses and antimicrobial activities of 4‐aryl‐5‐phenylimino‐3‐S‐(hepta‐O‐acetyl lactosyl)‐1,2,4‐thiadiazolines

A series of 4‐aryl‐5‐phenylimino‐3‐S‐(hepta‐O‐acetyl lactosyl)‐1,2,4‐thiadiazolines have been synthesized by the interaction of S‐(hepta‐O‐acetyl lactosyl)‐1‐arylisothiocarbamides and S‐chloro‐N‐phenyl isothiocarbamoyl chloride. The title compounds were characterized on the basis of elemental analysis and IR, NMR, mass spectral studies. The title compounds exhibited comparable antimicrobial activities against pathogens such as E. coli, S. aureus, P. vulgaris, S. typhi, A. niger, and Candida guilliermondii. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:390–392, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20310     

Synthesis and characterization of color‐stable electroluminescent polymers: Poly(dinaphtho[1,2‐a:1′,2′‐g]‐s‐indacene)s

Two new stepladder conjugated polymers, that is, poly(7,7,15,15‐tetraoctyldinaphtho[1,2‐a:1′,2′‐g]‐s‐indacene) (PONSI) and poly(7,7,15,15‐tetra(4‐octylphenyl)dinaphtho[1,2‐a:1′,2′‐g]‐s‐indacene) (PANSI) with alkyl and aryl substituents, respectively, have been synthesized and characterized. In comparison with poly(indenofluorene)s, both polymers have extended conjugation at the direction perpendicular to the polymer backbone because of the introduction of naphthalene moieties. The emission color of the polymers in film state is strongly dependent on the substituents. While PONSI emits at a maximum of 463 nm, PANSI with the same backbone but aryl substituents displays dramatically redshifted emission with a maximum at 494 nm. Both polymers show stable photoluminescence spectra while annealing at 200 °C in inert atmosphere. The PONSI‐based devices with the configuration of ITO/PEDOT:PSS/polymer/Ca/Al turn on at 3.7 V, and emit at a maximum of 461 nm with the CIE coordinates of (0.19, 0.26), a maximum luminance efficiency of 1.40 cd/A, and a maximum brightness of 2036 cd/m² at 13 V. Meanwhile, the emission color of the devices is independent of driving voltage and keeps unchanged during the continuous operation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4866–4878, 2008     

3‐Methylthio‐pyrano[4,3‐c]pyrazol‐4(2H)‐ones from 3‐(bis‐methylthio)methylene‐2H‐pyran‐2,4‐diones and hydrazines

A useful synthesis of 3‐methylthio‐6‐methyl‐pyrano[4,3‐c]pyrazol‐4(2H)‐ones via 3‐(bis‐methylthio)methylene‐5,6‐dihydro‐6‐alkyl(aryl)‐2H‐pyran‐2,4‐dione with hydrazine as well as methyl and phenyl hydrazines is described and the mechanism of the formation is discussed. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:342–344, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10158     

The use of 18O‐exchange and base‐catalyzed N‐dealkylation with liquid chromatography/tandem mass spectrometry to identify carbinolamide metabolites

Oxidation of N‐alkyl‐substituted amides is a common transformation observed in metabolism studies of drugs and other chemicals. Metabolism at the alpha carbon atom can produce stable carbinolamide compounds, which may be abundant enough to require complete confidence in structural assignments. In a drug discovery setting, rapid structural elucidation of test compounds is critical to inform the compound selection process. Traditional approaches to the analysis of carbinolamides have relied upon the time‐consuming synthesis of authentic standards or purification of large enough quantities for characterization by nuclear magnetic resonance (NMR). We describe a simple technique used in conjunction with liquid chromatography/tandem mass spectrometry (LC/MS/MS) which demonstrates the chemical identity of a carbinolamide by its distinctive ability to reversibly exchange [¹⁸O]water through an imine intermediate. A key advantage of the technique is that the chromatographic retention times of metabolites are preserved, allowing direct comparisons of mass chromatograms from non‐treated and [¹⁸O]water‐treated samples. Metabolites susceptible to the treatment are clearly indicated by the addition of 2 mass units to their original mass. An additional test which can be used in conjunction with ¹⁸O‐exchange is base‐catalyzed N‐dealkylation of N‐(α‐hydroxy)alkyl compounds. The use of the technique is described for carbinolamide metabolites of dirlotapide, loperamide, and a proprietary compound. Copyright © 2010 John Wiley & Sons, Ltd.