Construction of a combinatorial library of 2‐(4‐oxo‐4H‐1‐benzopyran‐3‐yl)‐4‐thiazolidinones by microwave‐assisted one‐pot parallel syntheses

A one‐pot liquid‐phase combinatorial synthesis of 2‐(4‐oxo‐4H‐1‐benzopyran‐3‐yl)‐4‐thiazolidinones bearing diverse substituents at the 3‐position under microwave irradiation was successfully performed using 3‐formyl chromone, primary amine, and mercaptoacetic acid as reactants. Compared to an identical library generated by conventional parallel synthesis, the microwave‐assisted parallel synthesis approach dramatically decreased the reaction time from an average of 9 h to 5 min, and substantially increased the product yields. The coupling of microwave technology with liquid‐phase combinatorial synthesis constitutes a novel and particularly attractive avenue for the rapid generation of structurally diverse libraries. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:381–389, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20309     

A novel one‐pot procedure for preparation of some new condensed pyrido[2,3‐d]pyrimidine(1H,3H)‐2,4‐diones

A novel one‐pot procedure for preparation of some new condensed pyrido[2,3‐d]pyrimidine(1H,3H)‐2,4‐diones based on condensation of ninhydrin, alkyl cyanoacetate, and 6‐aminouracil derivatives has been reported. The reactions were carried out in refluxed ethanol and were completed in less than 2 h. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:16–18, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20242     

Synthesis of 5‐methyl‐4‐oxo‐2‐(coumarin‐3‐yl)‐N‐aryl‐3,4‐dihydrothieno[2,3‐d]‐pyrimidine‐6‐carboxamides

Possible approaches to synthesis of 5‐methyl‐4‐oxo‐2‐(coumarin‐3‐yl)‐N‐aryl‐3,4‐dihydrothieno[2,3‐d]pyrimidine‐6‐carboxamides 4 have been discussed. It is shown that the preferable approach is cyclization of 2‐iminocoumarin‐3‐carboxamides 1 , utilizing 5‐amino‐3‐methyl‐N²‐arylthiophene‐2,4‐dicarboxamides 2 as binucleophilic reagents. The proposed procedure allowed us to easily obtain 4 in two stages, using common reagents. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:341–346, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20303     

Substituted pyridopyrimidinones, 1: Convenient PTC alkylation and halogenation of 2‐hydroxy‐4H‐pyrido[1,2‐a]pyrimidin‐4‐one

Alkylation of 2‐hydroxy‐4H‐pyrido[1,2‐a]pyrimidin‐4‐one ( 1 ) was investigated under solid–liquid phase transfer catalysis conditions (PTC), using tetrabutylammonium bromide and potassium carbonate. The reaction with alkyl halides led to the formation of various 2‐alkoxy products, in fair yields. Reaction of compound 1 with epichlorohydrin and chloroacetonitrile, under the same PTC conditions, afforded novel O1,O3‐disubstituted glycerol and oxazolopyridopyrimidone betaine derivatives, respectively. Some 3‐halo‐, 3,3‐dihalo, and/or 2,3‐dihalopyrido[1,2‐a]pyrimidines were also prepared using different halogenating agents at different reaction conditions. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:19–27, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20245     

On the chemistry of 5‐aryl‐2‐hydrazino‐benzo[6,7]cyclohepta[1,2‐b]pyrido[2,3‐e] pyrimidin‐4‐one

Several pyrido[2,3‐e]pyrimidine fused with other rings have been prepared by intramolecular cyclization of 5‐(4‐chlorophenyl)‐2‐hydrazino‐benzo [6,7]cyclohepta‐[1,2‐b]pyrido[2,3‐e]pyrimidine‐4‐one ( 1 ) with acids, carbon disulfide to form triazole derivatives ( 2,4 ), halo‐ketones to give triazine derivative ( 5 ), β‐ketoesters, β‐cyanoesters, and β‐diketones to yield 2‐(1‐pyrazolyl) derivatives ( 7,9,10 ), and aldehydes to form arylhydrazone derivatives ( 11a,b ) which cyclized to form triazoles ( 12a,b ). Also, acyclic N‐nucleosides are prepared by heating under reflux 2‐hydrazino‐benzo[6,7]cyclohepta[1,2‐b]pyrido[2,3‐e] pyrimidin‐4‐one ( 1 ) with xylose and glucose to give the corresponding acyclic N‐nucleosides ( 13a,b ) which are cyclized to afford the corresponding protected tetra and penta–O‐acetate C‐nucleosides ( 14a,b ). Deacetylating of the latter nucleosides afforded the free acyclic C‐nucleosides ( 15a,b ). © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:34–43, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20248     

Synthesis and antimicrobial activity of new functionalized derivatives of [1,2,4]triazolo[4,3‐a]pyrimidin‐5(1H)‐one

New functionalized 1,7‐diaryl‐6‐cyano‐1,2,4‐triazolo[4,3‐a]pyrimidin‐5(1H)‐one derivatives ( 5a–j ) were synthesized via reaction of 5‐cyano‐6‐phenyl‐2‐thiouracil 1 with the respective hydrazonoyl halides 2a–j and their biological activity was evaluated. The mechanism and the regioselectivity of the studied reactions are discussed. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:393–398, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20311     

Efficient synthesis of 1‐substituted‐4‐phenyl‐1, 4‐dihydro‐5H‐tetrazole‐5‐thione and (1‐phenyl‐1H‐tetrazol‐5‐yl)thioacetyl derivatives

A new and convenient synthesis of a variety of N‐ and S‐substituted tetrazoles has been developed via azide and Mannich reaction methods. Compounds were characterized by elemental analysis, MALDI MS, and ¹H NMR data. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:637–643, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20353     

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     

Self‐assembly of amphiphilic tris(2,2′‐bipyridine)ruthenium‐cored star‐shaped polymers

Amphiphilic tris(2,2′‐bipyridine)ruthenium‐cored star‐shaped polymers consisting of one polystyrene block and two poly(N‐isopropylacrylamide) blocks were prepared by the “arm‐first” method in which RAFT polymerization and nonconvalent ligand–metal complexation were employed. The prepared amphiphilic star‐shaped metallopolymers are able to form micelles in water. The size and distribution of the micelles were studied by dynamic light scattering and transmission electron microscopy techniques. Preliminary studies indicate that the polymer concentration and the hydrophilic poly(N‐isopropylacrylamide) block length can affect the morphologies of the formed metal‐interfaced core–shell micelles in water. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4204–4210, 2007     

Magnetic field effects on the polymerization of 6‐N,N‐dioctylamino‐1,3,5‐triazine‐2,4‐dithiol

Electrochemical polymerization of monosodium salt ( 1b ) of 6‐N,N‐dioctylamino‐1,3,5‐triazine‐2,4‐dithiol on stainless steels was investigated in zero (0T), perpendicular (5T⊥), and parallel (5T//) magnetic fields which are arranged perpendicular and parallel to the direction of electrolytic current. 5T⊥ magnetic field enhances the formation rate of poly(6‐N,N‐dioctylamino‐1,3,5‐triazine‐2,4‐disulfide) 2 films but suppresses the crystallinity of 2 . However, 5T// magnetic field enhances the formation rate and the crystallinity. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:60–64, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20257     

One‐ and two‐photon activity of cross‐conjugated photoinitiators with bathochromic shift

Intrigued by the good performance of 1,5‐diphenylpenta‐1,4‐diyn‐3‐one ( DPD ) as photoinitiator for radical polymerization we prepared and investigated several donor substituted derivatives. UV‐Vis spectroscopy revealed a gradual red‐shift of λ_max and higher extinction in the order of the donor capability. A methoxy‐substituted derivative ( O‐DPD ) exhibited significant photoinitiation activity in photo‐DSC experiments. Steady state photolysis experiments showed decreased decomposition rates with increasing donor capability. A dimethylamino derivative N‐DPD was even photostable under these conditions. Because of to the D‐π‐A‐π‐D system of these compounds two‐photon induced 3D photopolymerization experiments were performed and N‐DPD showed outstanding performance compared to often applied single photon initiators. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3280–3291, 2007     

Chemoselective synthesis of thieno[3,2‐c][1,8]naphthyridin‐4(5H)‐ones by tandem cyclization

A number of the thieno[3,2‐c][1,8]‐naphthyridin‐4(5H)‐ones are chemoselectively synthesized from 4‐(4′‐aryloxybut‐2′‐ynylthio)‐1‐phenyl‐1,8‐naphthyridin‐2(1H)‐ones in 82–90% yield by the formation of sulfoxide, followed by [2,3] and [3,3]sigmatropic rearrangement and an intramolecular Michael addition. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:87–92, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20234     

NO migration from N‐methyl‐N‐nitrosobenzene‐sulfonamide to 3,6‐dibromocarbazole: Concerted or stepwise reaction path?

The NO migration from N‐methyl‐N‐nitrosobenzene‐sulfonamide to 3,6‐dibromocarbazole was proposed in a recent literature to follow a stepwise reaction path. However, the present density functional theory calculations at the MP2/6–31G(d,p)//B3LYP/6–31G(d,p) level show that this reaction exclusively proceeds via a concerted mechanism involving a four‐membered ring transition state. The calculated barrier is in good agreement with the experimental finding. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Synthesis of novel 5‐aryl‐1H‐tetrazoles

In this study phenylselenocyanate and some of its derivatives (o‐Cl, p‐Cl, p‐Br, o‐NO₂, p‐NO₂, o‐CH₃, p‐CH₃, o‐COOH, p‐COOH, p‐OCH₃ substituted) were synthesized ( 3a–3j ). The synthesized compounds were converted to 5‐aryl‐1H‐tetrazole ( 4a–4j ), by Et₃N ċ HCl‐NaN₃ in toluene, which are a new series of phenylselanyl‐1H‐tetrazoles. The structure of all the presently synthesized compounds were confirmed using spectroscopic methods (FTIR, ¹H NMR, MS). © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:255–258, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20293     

Synthesis,characterization, and crosslinking of methacrylate‐telechelic PDMAAm‐b‐PDMS‐b‐PDMAAm copolymers

The synthesis and molecular characterization of a new amphiphilic conetwork (APCN) designed for silicone hydrogel use is described. The synthesis strategy, outlined in Scheme 1 , calls for the preparation, by the RAFT technique, of a new methacrylate‐telechelic amphiphilic pentablock, MA‐PHEA‐b‐PDMAAM‐b‐PDMS‐b‐PDMAAm‐b‐PHEA‐MA, and its crosslinking to the target APCN. The sketch shows the architecture of the APCN (dotted lines, PDMAAm; solid lines, PDMS; clusters, MA‐based crosslinking sites; see Fig. 3 ). All six synthesis steps proceed smoothly and efficiently, and the products are optically clear, colorless membranes exhibiting properties appropriate for ophthalmic use. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4284–4290, 2007     

A convenient synthesis of 2‐alkoxy‐2‐oxo‐1,4,2‐oxazaphosphinanes

A study on the synthesis of the novel cyclic α‐aminophosphonates and 2‐alkoxy‐2‐oxo‐1,4,2‐oxazaphosphinanes 4a‐r has been carried out. The title compounds were obtained in good yields by one‐pot procedure using o‐aminophenol, alkyl dichlorophosphinite, and ketones or benzaldehyde. One of their geometric stereoisomers was isolated and characterized. Configurations of 4k and one isomer of 4r have been established by X‐ray diffraction analysis. The synthetic methods provide an easy access to the organophosphorus heterocycles with the ring system mentioned above. The abnormal chemical shifts of alkyl‐substitute protons in ¹H NMR spectra were given reasonable explanation. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:65–69, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20258     

Organoaluminum‐mediated polymerization of diazoketones

Polymerization of diazoketones mediated by organoaluminum compounds was investigated. Trialkylaluminum R₃Al (R = iBu, Et, Me) and diisobutylaluminum hydride (DIBAL) polymerized (E)‐1‐diazo‐3‐nonen‐2‐one ( 1 ) to give polymers with M_n = 2000–3500, which contained nearly 33 mol % of azo group (? N?N? ) along with the dominant acylmethylene unit in the main chain. On the other hand, when (E)‐1‐diazo‐4‐phenyl‐3‐buten‐2‐one ( 2 ) was used as a monomer for the organoaluminum‐mediated polymerization, the resulting polymers had ethylidene (? CH[CH₃]? ) units in the main chain along with acylmethylene and azo group, as a result of reductive cleavage of the acyl group during the polymerization. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5209–5214, 2007     

Synthesis and characterization of model polybutadiene‐1,4‐b‐polydimethylsiloxane‐b‐polybutadiene‐1,4 copolymers

Model copolymers of poly(butadiene) (PB) and poly(dimethylsiloxane) (PDMS), PB‐b‐PDMS‐b‐PB, were synthesized by sequential anionic polymerization (high vacuum techniques) of 1,3‐butadiene and hexamethylciclotrisiloxane (D₃) on sec‐BuLi followed by chlorosilane‐coupling chemistry. The synthesized copolymers were characterized by nuclear magnetic resonance (¹H NMR), size‐exclusion chromatography (SEC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). SEC and ¹H NMR results showed low polydispersity indexes (M_w/M_n) and variable siloxane compositions, whereas DSC and TGA experiments indicated that the thermal stability of the triblock copolymers depends on the PDMS composition. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2726–2733, 2007     

Templated nanostructured PS‐b‐PEO nanotubes

With anodic aluminum oxide (AAO) membranes as wetting templates, nanotubes of the cylinder‐forming polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) copolymer were generated. The PS‐b‐PEO solution was introduced into the cylindrical nanopores of an AAO membrane by capillary force and polymeric nanotubes formed after solvent evaporation. Because of the water solubility of the cylindrical PEO microdomains and the orientation of the cylindrical PEO microdomains with respect to the nanotube walls, the nanotubes were permeable to aqueous media. PS‐b‐PEO nanotubes were also prepared on the interior walls of amorphous carbon nanotubes (a‐CNTs). Because of the unique water permeability of the PEO microdomains, an avenue for functionalizing the interior of the a‐CNTs is enabled. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2912–2917, 2007     

Helical poly(phenylacetylene) derived from L‐tyrosine: A promising candidate for functional helical polymers carrying transformable N‐ and C‐termini

A novel optically active phenylacetylene derivative, N‐(tert‐butoxycarbonyl)‐4‐ethynyl‐L ‐phenylalanine methyl ester ( 1 ), was synthesized from L ‐tyrosine and polymerized with a rhodium catalyst. The corresponding polymer [poly( 1 )] with a moderate molecular weight was obtained in a high yield. The alkaline hydrolysis of poly( 1 ) gave poly[N‐(tert‐butoxycarbonyl)‐4‐ethynyl‐L ‐phenylalanine] [poly( 2 )] carrying free carboxy groups. Polarimetric, CD, and UV–vis spectroscopy analyses revealed that poly( 1 ) took a predominantly one‐handed helical structure in MeOH and toluene, and poly( 2 ) took a helical structure in MeOH. The secondary structures of poly( 1 ) and poly( 2 ) could be tuned with heat and solvents. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1691–1698, 2007