A convenient synthesis of 2‐(1H‐1,2,4‐triazol‐1‐yl)‐2H‐1,4‐benzothiazine derivatives

A series of 2‐(1H‐1,2,4‐triazol‐1‐yl)‐2H‐1,4‐benzothiazines were designed and synthesized by condensation of 1,2,4‐triazole‐substituted ω‐bromoacetophenones and o‐aminothiophenols with the aid of K₂CO₃ under mild conditions with moderate to high yields. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:332–336, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20434     

Synthesis of 1‐(phenylsulfanyl/phenoxy)‐3H‐naptho[1,2,3‐de]quinoline‐2,7‐diones

A convenient method is devised to synthesize 1‐(phenylsulfanyl/phenoxy)‐3H‐naptho[1,2,3‐de]quinoline‐2,7‐dione analogs in high yield for the first time by condensation of 2‐bromo‐N‐(9,10‐dixo‐dihydro‐anthracen‐1‐yl)‐acetamide with benzenethiol/phenol using potassium carbonate. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:221–227, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20399     

MnCl2‐Promoted synthesis of quinoxaline derivatives at room temperature

MnCl₂ efficiently catalyzes the condensation of o‐phenylenediamine derivatives with 1,2‐diketones at room temperature to afford the corresponding quinoxaline derivatives in high yields. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:218–220, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20401     

Kaolin: A recyclable catalyst for the synthesis of 1,5‐benzodiazepines

2,3‐Dihydro‐1H‐1,5‐benzodiazepines are synthesized by the condensation of o‐phenylenediamine and various ketones in the presence of kaolin as a recyclable catalyst in dichloroethane. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:215–217, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20354     

Phospha‐michael reactions involving p‐heterocyclic nucleophiles

P‐heterocyclic γ‐ketophosphonates were synthesized by the Michael reaction of methyl vinyl ketone with dibenzo‐1,2‐oxaphosphorine 2‐oxide, 1,3,2‐dioxaphosphorine 2‐oxide and benzo‐1,3,2‐dioxaphospholane 2‐oxide, respectively. In the first two cases, 50% of 1,8‐diazabicyclo[5.4.0[undec‐7‐ene had to be used that was also required in the addition of dibenzooxaphosphorine oxide to cyclohexenone to result in the formation of the corresponding γ‐ketophosphonate. The addition of dibenzooxaphosphorine oxide to less reactive 1,2‐dihydrophosphinine oxide was accomplished after activation by an equimolar amount of trimethylaluminum to afford a 3‐P(O)<‐1,2,3,6‐tetrahydrophosphinine oxide, which was subjected to catalytic hydrogenation to provide the corresponding 1,2,3,4,5,6‐hexahydrophosphinine oxide. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:288–292, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20421     

A new P‐heterocyclic family: A variety of six‐membered and bridged P‐heterocycles with 1‐benzyl substituent

The ring enlargement of 1‐benzyl‐2,5‐dihydro‐1H‐phosphole oxide ( 1 ) via the corresponding 2‐phosphabicyclo[3.1.0]hexane 2‐oxide ( 2 ) afforded, depending on the conditions, the double bond isomers ( A and B ) of 1,2‐dihydrophosphinine oxide 4 or that of 3‐substituted 1,2,3,6‐tetrahydrophosphinine oxides 5 and 6 . Dihydrophosphinine oxides ( 4 ) were suitable starting materials for 1,2,3,4,5,6‐hexahydrophosphinine oxide 7 and 1,2,3,6‐tetrahydrophosphinine oxide 8 obtained by reductive approaches and for the double bond isomers ( A and B ) of 2‐phosphabicyclo[2.2.2]octadiene 2‐oxide 9 and phosphabicyclooctene oxide 10 prepared in Diels–Alder cycloaddition. Precursor 9 was utilized in the fragmentation‐related phosphorylation of alcohols. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:28–34, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20363     

Palladium N‐heterocyclic‐carbene‐catalyzed ortho‐arylation of benzaldehyde derivatives

New, sterically demanding 1,3‐dialkylbenzimidazolium salts ( 2a–c ) as N‐heterocyclic‐carbene precursors have been synthesized and characterized. The ortho position of aromatic aldehydes was directly and selectively arylated with aryl chlorides in the presence of a catalytic system prepared in situ from Pd(OAc)₂, 1,3‐dialkylbenzimidazolium chlorides ( 2a–c ), and Cs₂CO₃. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:569–574, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20479     

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     

Cobalt(II) chloride as a novel and efficient catalyst for the synthesis of 1,2,5‐trisubstituted pyrroles under solvent‐free conditions

CoCl₂ is used as an efficient catalyst in the Paal–Knorr condensation of 2,5‐hexadione with primary amines under solvent‐free conditions, leading to the formation of pyrrole derivatives in excellent yield. This method is very easy, rapid, and high yielding reaction for the synthesis N‐substituted pyrrole derivatives. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:592–595, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20482     

A new class of sulfur‐linked bis‐1,2,3‐selenadiazoles, 1,2,3‐thiadiazoles,and 2H‐diazaphospholes

Novel sulfur‐linked bis‐heterocycles, bis‐1,2,3‐selenadiazoles 4 , 1,2,3‐thiadiazoles 5 , and 2H‐diazaphospholes 7 , were synthesized from bis(2‐oxo‐2‐phenylethanone)sulfide 2 by adopting a simple and well‐versed methodology. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:261–265, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20425     

Synthesis and antimicrobial activity of 5,5′‐dimethyl‐2‐oxido‐[1,3,2]‐dioxaphos‐phorinane‐2‐yl‐amino carboxylates

Synthesis of several 5,5‐dimethyl‐2‐oxido‐[1,3,2]‐dioxaphosphorinane‐2‐yl‐amino carboxylates ( 4a–j ) was accomplished through a two‐step process. This involves prior preparation of the intermediate monochloride ( 2 ), 2‐chloro‐5,5‐dimethyl [1,3,2]dioxaphosphorinane‐2‐oxide and its subsequent reaction with various amino acid esters ( 3a–j ) in dry tetrahydrofuran in the presence of triethyl amine at room temperature. They were characterized by elemental analysis, IR, ¹H, ¹³C, ³¹P NMR, and mass spectral data. Their antifungal and antibacterial activity is also evaluated. Majority of these compounds exhibited moderate antimicrobial activity in the assay. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:256–260, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20426     

NMR signal assignment of cis/trans‐conformational segments in MEH‐CN‐PPV

Poly[2‐(2′‐ethylhexyloxy)‐5‐methoxy‐1,4‐phenylene‐(1‐cyanovinylene)] MEH‐CN‐PPV and its all‐trans model compound 1,4‐bis(α‐cyanostyryl)‐2‐(2‐ethylhexyloxy)‐5‐methyloxybenzene were synthesized via Knoevenagel condensation. All‐cis isomer and cis–trans isomer of 1,4‐bis(α‐cyanostyryl)‐2‐(2‐ethylhexyloxy)‐5‐methyloxybenzene were prepared by the photoisomerization reaction. Comparison of the ¹H NMR spectra between MEH‐CN‐PPV and three model compounds proved the occurrence of cis‐vinylene in the backbone of MEH‐CN‐PPV. According to the ratio between the cis‐vinylene signal and trans‐vinylene signal, the content of the cis‐vinylene could be estimated to be 15% in MEH‐CN‐PPV. This large cis‐vinylene content came from the rapid photochemical isomerization of cyanovinylene and was likely relative to the poor electroluminescence property of MEH‐CN‐PPV. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1105–1113, 2008     

Oxidative degradation of poly(isophthaloylhydrazine‐1,2‐diyl)s

The condensation polymerization of isophthalodihydrazide and diphenyl isophthalate affords poly(isophthaloylhydrazine‐1,2‐diyl). High‐molecular‐weight poly(5‐tert‐butylisophthaloylhydrazine‐1,2‐diyl) is prepared by the polycondensation of 5‐tert‐butylisophthalodihydrazide and bis(4‐nitrophenyl) 5‐tert‐butylisophthalate in NMP at 100 °C. T_d of the poly(diacylhydrazine) is observed above 300 °C. No T_g is observed below T_d. The high‐molecular‐weight poly(diacylhydrazine) exhibits a film‐forming ability. The poly(diacylhydrazine) decomposes on treatment with an oxidant such as sodium hypochlorite solution to obtain the corresponding carboxylic acid and nitrogen. However, poly(diacylhydrazine) was stable to oxygen and hydrogen peroxide even in the presence of transition metal ions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6255–6262, 2008     

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 of an electroluminescent polymer and its non‐doped light‐emitting diodes with stable green emission

An electroluminescent polymer was synthesized by Wittig condensation and characterized by the measurements of ¹H‐NMR, IR, gel permeation chromatography (GPC), UV–Vis, PL, and cyclic voltammetry (CV). The polymer can be dissolved in common organic solvents such as tetrahydrofuran (THF), chloroform, and dichloromethane. The electroluminescent investigation showed that the non‐doped devices with a double‐layer configuration (ITO/PEDOT:PSS/Polymer/Mg:Ag) have a stable green emission property. The maximum luminance of the annealed device reaches 2317 cd/m². The emission maximum and the CIE 1931 coordinate values are respectively stabilized at 552 nm and near (x, y) = (0.43, 0.55) with different voltages. Copyright © 2008 John Wiley & Sons, Ltd.     

A convenient and practical method for the synthesis of N‐thiophosphoryl aldimines and ketimines

A convenient and practical method for the preparation of N‐thiophosphoryl imines was developed through the thermal condensation of acetals with different thiophosphoramides at 120–160°C. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:238–244, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20412     

Development of catalyst‐transfer condensation polymerization. Synthesis of π‐conjugated polymers with controlled molecular weight and low polydispersity

We describe the development of chain‐growth condensation polymerization for the synthesis of well‐defined π‐conjugated polymers via a new polymerization mechanism, catalyst‐transfer polymerization. We first studied the condensation polymerization of Grignard‐type hexylthiophene monomer with a Ni catalyst as a part of our research on chain‐growth condensation polymerization, and found that this polymerization also proceeded in a chain‐growth polymerization manner. However, the polymerization mechanism involving the Ni catalyst was different from that of previous chain‐growth condensation polymerizations based on substituent effects; the Ni catalyst catalyzed the coupling reaction of the monomer with the polymer, followed by the transfer of Ni(0) to the terminal C? Br bond of the elongated molecule. This catalyst‐transfer condensation polymerization is generally applicable for the synthesis of polythiophene with an etheric side chain and poly(p‐pheneylene), as well as for the synthesis of polyfluorene via the Pd‐catalyzed Suzuki–Miyaura coupling reaction. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 753–765, 2008     

Generation and detection of the radical cation and the dication derived from 4,9‐diethyl[1,4]dihydrodithiino[5,6‐f]benzotrithiole and its 5‐oxide

4,9‐Diethyl[1,4]dihydrodithiino[5,6‐f]benzotrithiole (DTBT) gave a radical cation, DTBT(•+), and a dication, DTBT(2+), on treatment with a single‐electron oxidizing reagent. Both compounds showed an ESR signal, whereas the dication, generated by this procedure, was silent for ¹H NMR. Hydrolysis of DTBT(2+) gave DTBT 1‐oxide (DTBT 1‐O) and 2‐oxide (DTBT 2‐O) together with DTBT and a mixture of several dioxides. A singlet‐state dication, DTBT(2+)‐S, which was generated upon treatment of DTBT 5‐oxide (DTBT 5‐O) with concentrated D₂SO₄, was detected by ¹H and ¹³C NMR. After 20 h, the NMR signals disappeared while the solution was active for ESR. The results suggest that (i) a species generated from DTBT by oxidation with the single‐electron oxidizing reagent is a triplet‐state dication, DTBT(2+)‐T, and (ii) DTBT(2+)‐S, initially generated, gradually isomerizes to DTBT(2+)‐T in the solution, and DTBT(2+)‐T forms a partial spin pair. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:394–401, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20445     

A facile route to 1,5‐benzodiazepin‐2‐yl‐phosphonates via ytterbium chloride‐catalyzed three‐component reaction

1,5‐Benzodiazepin‐2‐yl‐phosphonates were facilely synthesized via a one‐pot three‐component condensation of o‐diaminobenzene, 1,3‐diketone and diethyl phosphite in the presence of a catalytic amount of ytterbium chloride under mild reaction conditions. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:89–95, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20573     

A convenient synthesis of novel 7‐phosphonylbenzyl‐2‐substituted pyrazolo[4,3‐e]‐1,2,4‐triazolo[1,5‐c]‐pyrimidine derivatives

A series of pyrazolo[4,3‐e]‐1,2,4‐triazolo‐[1,5‐c]pyrimidine derivatives, bearing phosphonylbenzyl chain in position 7, were conveniently synthesized in an attempt to obtain potent and selective antagonists for the A_2A adenosine receptor or potent pesticide lead compounds. Diethyl[(5‐amino‐4‐cyano‐3‐methylsulfanyl‐pyrazol‐1‐yl)‐benzyl]phospho‐nate ( 3 ), which was prepared by the cyclization of diethyl 1‐hydrazinobenzylphosphonate ( 1 ) with 2‐[bis(methylthio)methylene]malononitrile ( 2 ), reacted with triethyl orthoformate to afford diethyl[(4‐cyano‐5‐ethoxymethyleneamino‐3‐methylsulfanyl‐pyrazol‐1‐yl)‐benzyl]phosphonate ( 4 ), which reacted with various acyl hydrazines in refluxing 2‐methoxyethanol to give the target compounds 5a–h in good yields. Their structures were confirmed by IR, ¹H NMR, ¹³C NMR, MS, and elemental analysis. The crystal structure of 5e was determined by single crystal X‐ray diffraction © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:634–638, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20478