A reasonable criterion of reactivities at the defective region of single‐walled carbon nanotubes

Defect directional curvature K_D‐def was proposed as a reasonable criterion for the reactivities and adduct structures at the defective region of single‐walled carbon nanotubes (SWCNTs). B3LYP/6‐31G* calculations for the [2 + 1] and [1 + 1] additions of a series of 11‐layer (n, n) (n = 4–8) and six‐layer (10,0) SWCNTs with Stone‐Wales defects showed that the K_D‐def or its mean K_M‐def was a good index to judge the adduct structures and the reactivities. Adducts of the [2 + 1] additions were divided into two types: one was the adduct with the C‐X‐C configuration and corresponding to the large K_D‐def and the large binding energy, and another was the adduct with the closed ?3MR structure and corresponding to the small K_D‐def and the small binding energy. It must be pointed out that, besides mainly relying on the K_D‐def, the adduct structures and the reactivities of the [2 + 1] additions had been weakly affected by topologic structures. The calculated results for the [1 + 1] additions of the 11‐layer (5,5) SWCNT with defect A revealed that the binding energies monotonously increased with the K_M‐def. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

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     

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     

Synthesis of amphiphilic poly(methyl methacrylate‐ b‐ethylene oxide) copolymers from monohydroxy telechelic poly(methyl methacrylate) as macroinitiator

The synthesis of well‐defined poly(methyl methacrylate)‐block‐poly(ethylene oxide) (PMMA‐b‐PEO) dibock copolymer through anionic polymerization using monohydroxy telechelic PMMA as macroinitiator is described. Living anionic polymerization of methyl methacrylate was performed using initiators derived from the adduct of diphenylethylene and a suitable alkyllithium, either of which contains a hydroxyl group protected with tert‐butyldimethylsilyl moiety in tetrahydrofuran (THF) at ?78 °C in the presence of LiClO₄. The synthesized telechelic PMMAs had good control of molecular weight with narrow molecular weight distribution (MWD). The ¹H NMR and MALDI‐TOF MS analysis confirmed quantitative functionalization of chain‐ends. Block copolymerization of ethylene oxide was carried out using the terminal hydroxyl group of PMMA as initiator in the presence of potassium counter ion in THF at 35 °C. The PMMA‐b‐PEO diblock copolymers had moderate control of molecular weight with narrow MWD. The ¹H NMR results confirm the absence of trans‐esterification reaction of propagating PEO anions onto the ester pendants of PMMA. The micellation behavior of PMMA‐b‐PEO diblock copolymer was examined in water using ¹H NMR and dynamic light scattering. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2132–2144, 2008     

Co‐oxidation of ammonia and ethanol in supercritical water,part 2: Modeling demonstrates the importance of H2NNOx

A co‐oxidation model was constructed from available submechanisms for ammonia and ethanol oxidation. The ammonia submechanism validated for combustion at atmospheric pressure conditions was modified for the higher densities and lower temperatures (655–700°C) of supercritical water. The ethanol submechanism had previously been tested and validated at supercritical water conditions. The initial model poorly reproduced experimental ammonia conversion data and was not able to consistently match nitrous oxide production as a function of temperature over a range from 655–700°C at 246 bar. To improve model predictions, the low‐pressure NH₂ + NO_x submechanism was replaced with a submechanism that included the H₂NNO_x adduct species that are expected to be stabilized in the high‐pressure supercritical water environment. Thermochemical and kinetic parameters for the adduct species were estimated with quantum chemical calculations using Gaussian 98 with the CBS‐Q method. The explicit treatment of the H₂NNO_x adducts resulted in nitrous oxide yield predictions that correctly reproduced experimental trends. This work represents a vital first step in improving the understanding of ammonia oxidation in supercritical water. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 653–662, 2008     

A novel stereoselective synthesis of (2Z)‐2‐arylsulfanylallylic alcohols by tin–lithium exchange of (E)‐α‐stannylvinyl sulfides

Tin–lithium exchange reaction of (E)‐α‐stannylvinyl sulfides 1 with n‐butyllithium gave (Z)‐α‐arylsulfanylvinyllithiums 2 , which reacted with aldehydes or ketones 3 to afford stereoselectively (2Z)‐2‐arylsulfanylallylic alcohols 4 in good to high yields. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:639–643, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20487     

Synthesis,structure, and biological activity of novel 4,5‐disubstituted thiazolyl urea derivatives

Novel 1‐(2,4‐dichlorophenyl)‐3‐[4‐aryl‐5‐(1H‐1,2,4‐triazol‐1‐yl)thiazol‐2‐yl] urea derivatives were synthesized by the reaction of 2‐amino‐4‐sustituted phentyl‐5‐(1H‐1,2,4‐triazol‐1‐yl) thiazoles with 2,4‐dichloro‐1‐isocyanatobenzene. Structures of the title compounds were confirmed by the elemental analysis, ¹H NMR, and single crystal X‐ray diffraction analysis. Biological evaluation showed that some of them possess promising antitumor activities. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:2–6, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20375     

Stereochemical aspects of the hypophosphorous acid addition to terephthalic schiff bases. Synthesis of new 1,4‐phenylene‐bis‐aminomethane‐bis‐phosphonous acids

Terephthalic Schiff bases react with hypophosphorous acid to form 1,4‐phenylene‐bis‐N‐alkyl‐aminomethanephosphonous acids in moderate yields. NMR studies demonstrated that—for several examples—this reaction led to the exclusive formation of only one diastereomeric form. NMR investigation of a chiral salt identified the meso form. In contrast hereto, a corresponding addition of hypophosphorous acid to a chiral Schiff base proved to be not stereoselective; all three possible diastereoisomers were formed in a 4:1:1 ratio. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:283–287, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20422     

Facile synthesis of phosphorylated azides in ionic liquids and their use in the preparation of 1,2,3‐triazoles

The facile general synthetic route to azidoalkylphosphonates by the nucleophilic substitution reaction in a series of bromoalkylphosphonates was elaborated, using 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([bmim][PF₆]) as a recyclable reaction medium. These azidoalkylphosphonates were used as intermediates for copper(I)‐catalyzed regioselective 1,3‐dipolar cycloaddition with a variety of alkynes to afford 4‐substituted (1H‐1,2,3‐triazol‐1‐yl)alkylphosphonates as potential drug candidates. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:293–300, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20420     

Oxidation of diethyl N‐sulfinylphos‐phoramidates

It is reported that the diethyl N‐sulfinylphosphoramidate ( 1a ) is oxidized with iodoso‐ and/or iodoxybenzene as well as with organic peroxides, to give diethyl N‐sulfonylphosphoramidate ( 7a ). The latter was generated in situ at low temperature and trapped with dialkyl phosphoramidates, affording the N,N′ bis(dialkyl phosphor)sulfamides 3a–c . The oxidation of 1a with cumene peroxide in the presence of 2,2‐dimethyl‐propan‐1‐ol ( 9 ) produced the diethylphosphor‐N‐[2,2‐dimethylpropyl]sulfamate ( 10a ). © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:530–536, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20474     

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     

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     

Quantum chemical study on enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine. Part 3. Properties of intermediates during hydride transfer

In the current article, the structures and properties of intermediates during the hydride transfer for the prior coordination of the carbonyl oxygen of keto oxime ether at B(2) of oxazaborolidine are discussed. All the structures are optimized completely by means of the Hartree–Fock (HF) and the density functional methods at the HF/6‐31G(d) and Becke's three‐parameter exchange functional and the gradient‐corrected functional of Lee, Yang, and Paar (B3LYP)/6‐31G(d) levels. The hydride transfer from BH₃ to the carbonyl carbon in oxazaborolidine‐borane‐keto oxime ether adduct results in the formation of the adduct 4a* with a seven‐membered ring. This adduct has four stable structures. Another hydride of BH₂ transfers to the oxime carbon in 4a* , leading to the adduct 5a* , which has also four stable structures. Among all the structures of 5a* , the most stable structure can generate (1S, 2R)‐cis amino alcohol, which is in agreement with that obtained in the experiment. This enantioselective reduction may go through the process in which oxazaborolidine‐borane‐keto oxime ether adduct is directly transformed into the adduct 4a* with a seven‐membered ring. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 307–316, 2003     

Phosphorylation of N‐Silylpyrroles with Phosphorus Tribromide

Phosphorylation of N‐trimethylsilyl‐ and N‐dimethyl‐tert‐butylsilylpyrroles with phosphorus tribromide in pyridine proceeds selectively at position 3 of the pyrrole ring. Removal of the trialkylsilyl protecting group has furnished the first representatives of N‐unsubstituted 3‐phosphorylated pyrroles. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:93–96, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20416     

Synthesis of 1‐methoxypoly(oxyethylene)benzocyclobutene and its diels–alder reactions

A new poly(ethylene glycol) derivative, 1‐methoxypoly(oxyethylene)benzocyclobutene ( 1 ) was prepared from the reaction of 1‐benzocyclobutenyl 1‐hydroxyethyl ether with mesylate of methoxypoly(oxyethylene) in tetrahydrofuran. The degree of end‐group conversion, as determined by NMR, was 100%. The Diels–Alder reactions of 1 with maleic anhydride and N‐phenylmaleimide were carried out in refluxing toluene to obtain the corresponding adducts ( 2 and 3 , respectively) in excellent yields. NMR analyses of 2 and 3 indicated complete conversion of 1 to the corresponding products. The reaction of 2 with o‐toluidine resulted in complete conversion of the anhydride adduct to the corresponding products. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1934–1938, 2004     

Synthesis and fungicidal activity of O‐alkyl O‐aryl O‐2‐(stearamido)ethyl phosphates

N‐stearoylethanolamine (NAE18:0) was reacted with O‐alkyl O‐aryl chlorophosphate and a series of O‐alkyl O‐aryl O‐2‐(stearamido)ethyl phosphates were synthesized to explore their antifungal activity. Compared with parent NAE18:0, title compounds without substitution or with methyl substitution on a benzene ring exhibited improved antifungal activity. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:602–608, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20485     

Convenient synthesis of optically active α‐hydroxyphosphinic acids

The reaction of O‐menthyl phenylphosphonite 1 with aromatic aldehydes in the presence of Me₃SiCl provided the O‐menthyl α‐hydroxyphosphinates 2 . Acidic hydrolysis of 2 gave the corresponding α‐hydroxyphosphinic acids 3 . The (+)‐enantiomer of 3a and 3b , adduct of benzaldehyde and 4‐methylbenzaldehyde respectively, were obtained via multiple recrystallization. The absolute configuration of (+)‐ 3a was determined as S by X‐ray crystallography. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:312–315, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10150     

Novel routes to aminophosphonic acids: Interaction of dimethyl H‐phosphonate with hydroxyalkyl carbamates

It was found that the reaction of dimethyl H‐phosphonate ( 1 ) with 2‐hydroxyalkyl‐N‐2′‐hydroxyalkyl carbamates at 135°C includes several chemical reaction steps: (i) chemical transformations of 1‐methyl‐2‐hydroxyethyl‐N‐2′‐hydroxyethyl carbamate ( 2 ) and 2‐methyl‐2‐hydroxyethyl‐N‐2′‐hydroxyethyl carbamate ( 3 ); (ii) transesterification of dimethyl H‐phosphonate with 2 and 3 , and with secondary hydroxyl‐containing compounds that are formed during the course of the chemical transformation of 2‐hydroxyalkyl‐N‐2′‐hydroxyalkyl carbamates; (iii) hydrolysis of 1 and dialkyl H‐phosphonates, formed via transesterification of 1 with secondary hydroxyl‐containing compounds. The interaction was studied by means of ¹H, ¹³C, ³¹P NMR, and FAB mass spectroscopy. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:119–124, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20404     

An efficient and green method for the synthesis of N‐phosphoramino o‐hydroxylphenyl α‐aminophosphonic monoesters

An efficient and green method to the synthesis of N‐protected o‐hydroxylphenyl α‐amino‐alkylphosphonic monoesters is described. It consists of the three‐component Mannich‐type reaction of phosphoramides, carbonyl compounds (aldehydes or ketones), and 2‐chlorobenzo[1,3,2] diox‐aphospholes under solvent‐free and catalyst‐free conditions, followed by hydrolysis. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:596–601, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20483