bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of salt‐tolerant membrane adsorbers for viral clearance
Authors: Riordan William , Heilmann Steve , Brorson Kurt , Seshadri Kannan , He Yi , Etzel Mark
Published: March 2009

Strong anion exchange chromatography has frequently been employed as a viral clearance step during downstream processing of biological therapeutics. When challenged with viruses having only slightly acidic isoelectric points, the performance of the anion exchange operation becomes highly dependent on the buffer salt concentration, with the virus log reduction value (LRV) dropping dramatically in buffers with 50–150 mM salt. In this work, a series of anion exchange membrane adsorbers utilizing alternative ligand chemistries instead of the traditional quaternary amine (Q) ligand have been developed that overcome this limitation. Four different ligands (agmatine, tris‐2‐aminoethyl amine, polyhexamethylene biguanide, and polyethyleneimine) achieved >5 LRV of bacteriophage ΦX174 (pI ∼ 6.7) at pH 7.5 and up to 150 mM salt, compared to 0 LRV for the Q ligand. By evaluating structural derivatives of the successful ligands, three factors were identified that contributed to ligand salt tolerance: ligand net charge, ligand immobilization density on the membrane, and molecular structure of the ligand‐binding group. Based on the results of this study, membrane adsorbers that incorporate alternative ligands provide a more robust and salt tolerant viral clearance‐processing step compared to traditional strong anion exchange membrane adsorbers. Biotechnol. Bioeng. 2009;103: 920–929. © 2009 Wiley Periodicals, Inc.
Synthesis of L‐valine crystals
Authors: Ramachandran E. , Natarajan S.
Published: March 2009

L‐valine (C5H11NO2), an essential amino acid of monoclinic space group P21, Z = 4 and lattice parameters a = 9.688 (2) Å, b = 5.267 (1) Å, c = 11.980 (2) Å and β = 90.75 (1)° and of size: 6.0 mm across and 0.5 mm thick was crystallized in silica gel under suitable pH conditions by reduction of solubility method. Density measurement and single crystal X‐ray diffraction were used to characterize the grown crystals. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopic (SEM) studies were made and crystal packing also discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some features of thermo‐activated structural transformation of biogenic and synthetic Mg‐containing apatite with β‐tricalcium‐magnesium phosphate formation
Authors: Danilchenko S. N. , Protsenko I. Yu. , Sukhodub L. F.
Published: March 2009

Temperature transformation of biogenic and synthetic Mg‐containing apatite with β‐tricalcium‐magnesium phosphate (β‐TCMP) formation was investigated by X‐ray diffraction. Samples were annealed in air at the temperature range from 600 to 1200 °C at intervals 100 °C and cooled down to room temperature. The appearance of β‐TCMP was ascertained in samples annealed at 800 °C. As revealed, the relative amount of β‐TCMP increases and Mg concentration in this phase decreases as the annealing temperature is raised. While this, the replacement degree of Ca by Mg in the β‐TCMP lattice is the annealing temperature function and does not depend either on sample origin (biogenic/synthetic) or on initial Mg concentration. The results of present work together with other investigation data testify to a high thermally activated mobility of Mg both in structure of Mg‐containing apatites and in the structure of β‐TCMP formed after thermal decomposition. Obtained data can be used for new biomaterials design with varied prolongation of Mg released into the living biological tissue. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Predicting a major role of surface spins in the magnetic properties of ferrite nanoparticles
Authors: Obaidat I. M. , Mohite V. , Issa B. , Tit N. , Haik Y.
Published: March 2009

Room‐temperature magnetization hysterisis measurements were conducted on Mn0.5Zn0.5GdxFe(2‐x)O4 ferrite nanoparticles, with x = 0, 0.5, 1.0, 1.5. The structure of this ferrite is normal spinel where the added of Gd3+ ions occupied the octahedral sites and replaces Fe3+ ions. The saturation magnetization was found to increase with the initial addition of the Gd3+ ions followed by a sharp decrease with further addition of Gd3+ ions. The Curie temperature was found to increase up to Gd3+ concentration of x = 1.0, and then decreases at x = 1.5. These results were attributed to the surface spins. Because the size of Gd3+ ions is larger than that of Fe3+ ions, the substitution of Fe3+ ions with the Gd3+ ions results in surface disorder which results in surface spins. A core‐shell magnetization model was introduced where several factors were combined to explain our results. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recovery process of sciatic nerve defect with novel bioabsorbable collagen tubes packed with collagen filaments in dogs
Authors: Okamoto Hideki , Hata Ken‐Ichiro , Kagami Hideaki , Okada Kunihiko , Ito Yuki , Narita Yuji , Hirata Hitoshi , Sekiya Isato , Otsuka Takanobu , Ueda Minoru
Published: March 2009

Autologous nerve graft is the most commonly applied treatment for the patients with peripheral nerve defect, while application is limited because of tissue availability and unfavorable donor site morbidity. To overcome this problem, peripheral nerve regeneration using a nerve conduit has been studied. Especially, nerve conduit using biodegradable materials has been considered promising. In this study, a potential of collagen nerve conduit has been studied with special reference to the regenerating process of a peripheral nerve. Twelve adult female Beagle dogs weighting 10–12 kg were used. The peroneal nerve was cut to make a 30‐mm defect. The nerve defect was bridged by the collagen artificial nerve conduit. Comprehensive functional, electrophysiological, morphometrical, and histlogical analyses were performed until one year after operation. The wet weight of tibialis anterior muscles was only 32.4% of the healthy side at 24 weeks, which was recovered to 77.4% at 52 weeks after denervation. Electrophysiological evaluation of tibialis anterior muscle belly showed polyphasic wave at 52 weeks after implantation, which was almost half amplitude as compared with that of control. The diameters of myelinated nerve fibers thickened day by day, and the average diameter was 5.16 μm at PFN, 3.91 μm at CG, and 3.75 μm at DFN, and average thickness of myelin sheath was 0.94 μm at PFN, 0.46 μm at CG, and 0.55 μm at DFN after 52 weeks. The distribution of myelinated nerve fiber size in the 52 weeks group was distinctly bimodal with the major peak at approximately 2–4 μm and the minor peak at 10–12 μm. These findings were consistent with the distribution of the normal nerve fiber. This study proves the feasibility of the collagen artificial nerve conduit for promoting nerve regeneration, raises new possibilities of seeking alternatives to autograft for nerve repair. The results from this study showed detailed process of morphological, electrophysiological, and functional recovery of the regenerated nerve, which would provide scientific background for this novel therapy © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
NMP‐modified PMMA bone cement with adapted mechanical and hardening properties for the use in cancellous bone augmentation
Authors: Boger Andreas , Wheeler Kurtis , Montali Andrea , Gruskin Elliot
Published: March 2009

The use of polymethylmethacrylate (PMMA) to reinforce vertebral bodies (Vertebroplasty) leads to an increase in the Young's modulus of the augmented vertebral body. Fractures in the adjacent vertebrae may be the consequence thereof. Hence, PMMA with a reduced Young's modulus may be suitable for vertebroplasty. The goal of this study was to produce and characterize stiffness‐adapted PMMA cements. Modified PMMA bone cements were produced by adding N‐methyl‐pyrrolidone (NMP). Young's modulus, yield strength, polymerization temperature, setting time, and hardening behavior of different cements were analyzed. Focus was on the mechanical properties of the material after different storage conditions (in air at room temperature and in PBS at 37°C). The Young's modulus decreased from 2670 MPa (air)/2384 MPa (PBS) for the regular cement to 76 MPa (air)/320 MPa (PBS) for a material composition with 60% of the MMA substituted by NMP. Yield strength decreased from 85 MPa (air)/78 MPa (PBS) to 2 MPa (air)/24 MPa (PBS) between the regular cement and the 60% composition. Polymerization temperature decreased from 70°C (regular cement) to 48°C for the 30% composition. The hardening behavior exhibited an extension in handling time up to 200% by the modification presented. Modification of PMMA cement using NMP seems to be a promising method to make the PMMA cement more compliant for the use in cancellous bone augmentation in osteoporotic patients: adjustment of its mechanical properties close to those of cancellous bone, lower polymerization temperature, and extended handling time. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2009
On the amination of azaheterocycles. A new procedure for the introduction of an amino group
Authors: Hara Hiroshi , Van Der Plas Henk C.
Published: March 2009

A new method of amination of diazines and triazines, using potassium amide, liquid ammonia and potassium permanganate, has been described.
On the reaction of 2‐aminopyridines with alpha‐halocarbonyl compounds
Authors: Elliott Arthur J. , Guzik Henry , Soler Jose R.
Published: March 2009

The reactions of 6‐substituted‐2‐aminopyridines with bromoacetone and 3‐bromo‐2‐butanone have been investigated. In contrast to bromoacetone which gives a high yield of the imidazo[1,2‐a]pyridine, bromobutanone also produces significant amounts of material derived from substitution on the exocyclic nitrogen atom. These adducts, which are not a source of imidazopyridine in the reaction mixture, may be isolated and cyclised under more forcing conditions. The reactions of 2‐aminopyridine with 2‐chlorocyclohexanone and phenacyl bromide have been re‐examined and all the major products identified.
An alternate synthesis of 6‐substituted‐5‐deazapteridines
Authors: Degraw Joseph I. , Tagawa Hiroaki
Published: March 2009

A procedure for synthesis of 2,4‐diamino‐6‐substituted‐5‐deazapteridines (pyrido[2,3‐d]pyrimidines) is described. Condensation of 1‐piperidino‐1‐propene with ethoxymethylenemalononitrile afforded an enamino malononitrile adduct, which when treated with ammonia yielded 2‐amino‐3‐cyano‐5‐methylpyridine. Cyclization to 2,4‐diamino‐6‐methyl‐5‐deazapteridine could be effected with guanidine. Similar condensation of piperidinopropene with ethyl methoxymethylenecyanoacetate followed by cyclization with hydroxylamine gave 2‐amino‐3‐carbethoxy‐6‐methylpyridine 1‐oxide. Reduction with phosphorus trichloride afforded the pyridine base, however, attempts to cyclize the amino ester to 2‐amino‐4‐hydroxy‐6‐methyl‐5‐deazapteridine were unusccessful.
The alkylation of 3H‐phenoxazin‐3‐one derivatives
Authors: Ueno Yoshio
Published: March 2009

2‐Alkyl‐, 4‐alkyl‐, and 2,4‐dialkyl‐3H‐phenoxazin‐3‐ones were prepared by reacting 3H‐phenoxazin‐3‐one with alkyl radicals in aqueous acetonitrile at 70–75°. The alkyl radicals were generated from the silver catalysed oxidative decarboxylation of acids with peroxydisulphate.
Characterization of geometric isomers of norbornene end‐capped imides
Authors: Young Philip R. , Chang A. C.
Published: March 2009

Three geometric isomers from the thermal isomerization of methylene‐4,4′‐bis(endo‐N‐phenylbicyclo‐[2.2.1]hept‐2‐ene‐5,6‐dicarboximide) (I) were chromatographically separated and isolated. Nmr spectroscopy was used to assign endo‐endo (I), endo‐exo (II), and exo‐exo (III) configurations to each compound. The three isomers, which serve as model compounds for norbornene end‐capped polyimides, were then characterized by several chromatographic, spectroscopic, and thermal techniques. Upon heating, each isomer was found to establish an equilibrium mixture of all three isomers. The possibility that the compounds react by different mechanisms in air and in nitrogen is proposed.
Hydrolysis of amides. Kinetics and mechanism of the basic hydrolysis of N‐acylpyrroles, N‐acylindoles and N‐acylcarbazoles
Authors: Linda P. , Stener A. , Cipiciani A. , Savelli G.
Published: March 2009

The hydroxide ion catalyzed hydrolysis of N‐formyl, N‐acetyl and N‐benzoylpyrroles, ‐indoles and ‐carbazoles has been studied in water at 25.0°. The rate constants of formation of the tetrahedral intermediate are strongly increased by releasing steric hindrance in the acyl portion as shown by the higher reactivity of N‐formyl derivatives in comparison with N‐acetyl and N‐benzoyl derivatives.
Synthesis of 1‐substituted‐2,3,4,9‐tetrahydro‐(2‐oxopropyl)‐1H‐pyrido [3,4‐b] indoles and their base‐catalyzed rearrangements to N‐ [2‐[2‐(1‐alkyl‐3‐oxobutenyl)‐1H‐indol‐3‐yl] ethyl]acetamides
Authors: Bobowski George
Published: March 2009

The condensation of 1H‐indole‐3‐ethanamides, 1, with 2,4‐pentanediones, 2, gave enamines 3. Acid catalyzed ring closure of 3 gave 1‐(1‐substituted‐2,3,4,9‐tetrahydro‐ (2‐oxopropyl) ‐1H‐pyrido [3,4‐b] indoles 4. Subsequent N‐acetylation yielded 5 which sequentially produced 2,3‐disubstituted indoles 6 and 7 resulting from CN bond cleavage after treatment with sodium alkoxide in ethanol. Controlled catalytic hydrogenation of the latter gave saturated derivatives 8 and 9.
Synthesis of 1,2,3,4‐tetrahydroquinazoline derivatives as potential alpha‐adrenergic blocking agents
Authors: Granados R. , Alvarez M. , Vails N. , Salas M.
Published: March 2009

The synthesis of N,N′‐bis[6‐(1,2,3,4‐tetrahydro‐3‐quinazolidyl)hexyl]cystamine (I) and 3‐(6‐aminohexyl)‐1,2,3,4‐tetrahydroquinazoline (II) are described. Compound I is obtained by condensation of o‐nitrobenzoyl chloride with 3‐(6‐aminohexyl)‐1,3‐thiazolidine (III) followed by dimerization, reduction and formation of tetrahydroquinazoline ring. A similar method was used for preparation of compound II. These compounds and some synthesis intermediates are potential alpha‐adrenergic blockers.
2‐(4‐alkylamido‐2‐hydroxyphenyl)benz‐X‐azoles as intermediates for the synthesis of dyes
Authors: Barni Ermanno , Savarino Piero , Marzona Mario , Piva Marco
Published: March 2009

Nineteen substituted 2‐phenylbenz‐X‐azoles, which are intermediates for the synthesis of dyes, were prepared from p‐aminosalicylic acid (PAS). Substituents in the phenyl ring are 2′‐hydroxy and/or 4′‐amino and 4′‐alkylamido with alkyl chains ranging from C1 to C15. The preferred route of the synthesis is discussed. The melting points and the Rf values are correlated with the structure. An extensive discussion of the electronic absorption spectra, involving other compounds with the same general structure, is reported.
Some new methods for preparing 2,3‐ and 3,4‐diaminopyridines
Authors: Campbell J. B. , Greene J. M. , Lavagnino E. R. , Gardner D. N. , Pike A. J. , Snoddy J. , Taylor E. C.
Published: March 2009

New methods of preparing 2,3‐diaminopyridine (13) from 2‐chloro‐3‐nitropyridine (11) and 3,4‐diaminopy‐ridine (8) from 4‐ethoxy‐3‐nitropyridine hydrochloride (5) have been explored and evaluated.
Preparation and characterization of 6‐substituted 1,8‐diazabicyclo[5.4.0]undec‐7‐ene
Authors: Matsumura Noboru , Nishiguchi Hiroshi , Okada Masao , Yoneda Shigeo
Published: March 2009

The lithium 1,8‐diazabicyclo[5.4.0]undec‐6‐ide (1) prepared from 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) and n‐butyllithium reacts with alkyl halides and carbonyl compounds such as benzophenone, acetophenone, and benzaldehyde to give 6‐substituted DBU derivatives in good yields. The reaction behavior of 6‐substi‐tuted DBU was also investigated.
An unexpected aminolysis in the synthesis of 5‐substituted 3‐(1H‐tetrazol‐5‐yl)pyrazolo[1, 5‐a]quinazolines
Authors: Peet Norton P.
Published: March 2009

A synthetic route to 5‐substituted 3‐(1H‐tetrazol‐5‐yl)pyrazolo[1, 5‐a]quinazolines is described. An unexpected displacement of a 4‐morpholinyl group from the 5‐position of this system occurred during tetrazole formation by the ammonia produced byin situgeneration of hydrazoic acid from ammonium chloride and sodium azide.
Cyclization reactions of 3‐hydrazino[1, 2, 4]triazino[5, 6‐b]indole
Authors: Abdel‐Latif F. F. , Shaker R. M. , Mahgoub S. A. , Badr M. Z. A.
Published: March 2009

The reaction of 3‐hydrazino[1, 2, 4]triazino[5, 6‐b]indole I with nitrous acid affords the azide III which could be cyclized with acetic anhydride to 10‐acetyl‐10H‐tetrazolo[5′,1′:3, 4][1, 2, 4]triazino[5, 6‐b]indole IIb. Cyclization reactions of I with acetic anhydride, ethyl chloroformate, carbon disulphide and aromatic aldehydes to the corresponding fused triazolo derivatives V–VIII are reported. On the other hand cyclization reactions of I with malononitrile, ethyl cyanoacetate, ethyl acetoacetate and acetylacetone to the corresponding condensed pyrazolino derivatives IX–XI are also reported. The reaction of I with α‐dicarbonyl compounds to form mono and dihydrazones are reported. The structure of the compounds prepared and their cyclization mechanisms are reported.
Synthesis and reactions of 2‐amino‐7, 8‐dimethoxy‐1h‐3‐benzazepines. Competitive formation of 2‐amino‐1h‐3‐benzazepinesvs. 2‐benzylimidazoles
Authors: Robey R. L. , Copley‐Merriman C. R. , Phelps M. A.
Published: March 2009

A short synthesis of 2‐amino‐7, 8‐dimethoxy‐1H‐3‐benzazepine (1a) from 3, 4‐dimethoxyphenylacetonitrile (8a) is reported. The synthesis of several other 2‐amino‐1H‐3‐benzazepines1is also discussed. Conditions which favor the formation of1versusthe formation of the isomeric 2‐benzylimidazoles11are evaluated. Several reactions of1aare also described.
Syntheses of 4,7‐Dimethyl‐6‐phenyl‐5,6,7,8‐tetrahydro‐4H‐1,3,6‐dioxazocin‐2‐ones and its related compounds
Authors: Nishiyama Tomihiro , Yamaguchi Hiromasa , Yamada Fukiko
Published: March 2009

Four isomeric 4,7‐dimethyl‐6‐phenyl‐5,6,7,8‐tetrahydro‐4H‐1,3,6‐dioxazocin‐2‐ones and four isomeric 4,7‐dimethyl‐6‐phenyl‐5,6,7,8‐tetrahydro‐4H‐1,3,2,6‐dioxathiazocine 2‐oxides were prepared. On the basis of the nmr chemical shifts due to the γ‐effect, the stereochemical structures are discussed.
A Synthesis of imidazo‐ and pyrimido[1,2‐g][1,6]naphthyridinones
Authors: Friary R. , Schwerdt J. H. , Seidl V. , Villani F. J.
Published: March 2009

Arylmethylimidazolines and (3‐chlorophenyl)methyl‐1,4,5,6‐tetrahydropyrimidine amidated 2‐chloro‐3‐pyridinecarbonyl chloride, and potassiumt‐butoxide cyclized the products to linearly fused, tricyclic imidazo‐and pyrimido[1,2‐g][1,6]naphthyridinones. Condensation of ethyl 2‐chloro‐3‐pyridinecarboxylate with 2‐(phenylmethyl)imidazoline in the presence of sodium methoxide directly formed the isomeric, angularly fused 8,9‐dihydro‐6‐phenylimidazo[1,2‐a][1,8]naphthyridin‐5(7H‐one.
Synthesis and stereochemistry of novel [1,2,4]oxadiazolo[4,5‐a][1,5]benzodiazepine derivatives
Authors: Chimirri Alba , Grasso Silvana , Ottanà Rosaria , Romeo Giovanni , Zappalà Maria
Published: March 2009

An one‐pot synthetic approach to the novel 3a,4,5,6‐tetrahydro[1,2,4]oxadiazolo[4,5‐a][1,5]benzodiazepine system, by 1,3‐dipolar cycloaddition of benzonitriloxides to 1,5‐benzodiazepine derivatives, is described. The structure and stereochemistry of the obtained adducts have been assigned by means of spectroscopic measurements.
Synthesis of certain pyrazolo[3,4‐d]pyrimidin‐3‐one nucleosides
Authors: Anderson Jack D. , Cottam Howard B. , Larson Steven B. , Dee Nord L. , Revankar Ganapathi R. , Robins Roland K.
Published: March 2009

Synthesis of the pyrazolo[3,4‐d]pyrimidin‐3‐one congeners of guanosine, adenosine and inosine is described. Glycosylation of 3‐methoxy‐6‐methylthio‐1H‐pyrazolo[3,4‐d]pyrimidin‐4(5H)‐one (13) with 1‐O‐acetyl‐2,3,5‐tri‐O‐benzoyl‐D‐ribofuranose (16) in the presence of boron trifluoride etherate gave 3‐methoxy‐6‐methylthio‐1‐(2,3,5‐tri‐O‐benzoyl‐β‐D‐ribofuranosyl)pyrazolo[3,4‐d]pyrimidin‐4(5H)‐one (17) which, after successive treatments with 3‐chloroperoxybenzoic acid and methanolic ammonia, afforded 6‐amino‐3‐methoxy‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidin‐4(5H)one (18). The guanosine analog, 6‐amino‐1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidine‐3,4(2H,5H)‐dione (21), was made by sodium iodide‐chlorotrimethylsilane treatment of 6‐amino‐3‐methoxy‐1‐(2,3,5‐tri‐O‐acetyl‐β‐D‐ribofuranosyl)pyrazolo[3,4‐d]pyrimidin‐4(5H)one (19), followed by sugar deprotection. Treatment of the adenine analog, 4‐amino‐1H‐pyrazolo[3,4‐d]pyrimidin‐3(2H)‐one (11), according to the high temperature glycosylation procedure yielded a mixture of N‐1 and N‐2 ribosyl‐attached isomers. Deprotection of the individual isomers afforded 4‐amino‐3‐hydroxy‐1‐βribofuranosylpyrazolo‐[3,4‐d]pyrimidine (26) and 4‐amino‐2‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidin‐3(7H)‐one (27). The structures of 26 and 27 were established by single crystal X‐ray diffraction analysis. The inosine analog, 1‐β‐D‐ribofuranosylpyrazolo[3,4‐d]pyrimidine‐3,4(2H,5H)‐dione (28), was synthesized enzymatically by direct ribosylation of 1H‐pyrazolo[3,4‐d]pyrimidine‐3,4(2H,5H)‐dione (8) with ribose‐1‐phosphate in the presence of purine nucleoside phosphorylase, and also by deamination of 26 with adenosine deaminase.
Nitration studies of naphtho[2,3‐c][1,2,5]thiadiazole
Authors: Smith Walter T. , Patterson John M. , Kovelesky Albert C.
Published: March 2009

Nitration of naphtho[2,3‐c][1,2,5]thiadiazole gives the 5‐nitro derivative in 61–66% yield. Chlorination of this product apparently gives an unstable addition product which loses hydrogen chloride on recrystallization to give 4‐chloro‐8‐nitronaphtho[2,3‐c][1,2,5]thiadiazole. Thus, naphtho[2,3‐c][1,2,5]thiadiazole under nitrating conditions behaves as a 2‐substituted naphthalene rather than as an anthracene analog.
A 1H and 13c Nmr study of the structure and tautomerism of 4‐pyrazolylpyrazolinones
Authors: Elguero J. , Martíanez A. , Singh S. P. , Grover M. , Tarar L. S.
Published: March 2009

It has been established that the primary reactions products between dehydroacetic acid and p‐chlorophenylhydrazine or 4‐phenylthiazol‐2‐ylhydrazine are 4‐acetylacetyl‐5‐hydroxypyrazoles. These compounds react with the above hydrazines to yield 4‐(pyrazol‐5′‐yl)‐2‐pyrazolin‐5‐ones which exist in solution as 5‐hydroxypyrazoles.
Synthesis and stereochemistry of tetrahydro‐4‐aryl‐3‐[(dimethylamino)methyl]‐2H‐pyranols as potential analgesics
Authors: Mohacsi Erno , O'Brien Jay P. , Blount John F. , Sepinwall Jerry
Published: March 2009

Diastereomericcis‐ andtrans‐tetrahydro‐4‐aryl‐3‐[(dimethylamino)methyl]‐2H‐pyranols derived from 3‐[(dimethylamino)methyl]tetrahydro‐4H‐pyran‐4‐one (5), have been prepared and their configurations were established on the basis of ir data. The biologically more potenttransisomer3was resolved into its optical antipodes and the absolute stereochemistry of one of the enantiomers14, was determined by X‐ray crystallography. Some of the compounds showed analgesic activity comparable to codeine.
The improved convergent syntheses of arecolones and isoarecolone
Authors: Ward John S. , Merritt Leander
Published: March 2009

Good yields of arecolone and isoarecolone were obtained by treating theN,O‐dimethylamides of arecaidine and isoarecaidine, respectively, with methylmagnesium chloride. Other substituted arecolones were synthesized by this same strategy.
The electron transfer reactions of cyano substituted pyridines and quinolines with thermally generated diphenyl ketyl
Authors: Mcdevitt Patricia , Vittimberga Bruno M.
Published: March 2009

Electron transfer reactions of cyano substituted pyridines and quinolines with thermally generated diphenyl ketyl are reported. When E1/2(‐) for the heterocycle is less negative than ‐2V, electron transfer occurs from the ketyl to the heterocyclic base. In some cases the products obtained from the thermal reaction are the same as those obtained from the photochemical reaction with benzophenone and alcohols. In other cases different products are formed. Two bases, 2‐pyridinecarbonitrile and 2,4‐pyridinedicarbonitrile, undergo regiospecific reactions in which the course of the reaction is determined by the acidity of the medium. A mechanism in which the heterocyclic nitrogen is involved in the substitution process at the 2 position is proposed.
An improved synthesis of 3,6‐diamino‐1,2,4,5‐tetrazine. I
Authors: Coburn Michael D. , Ott Donald G.
Published: March 2009

Treatment of 1,3‐diaminoguanidine monohydrochloride (1) with 2,4‐pentanedione (2) in alcohols under carefully controlled conditions gave 3,6‐diamino‐1,2‐dihydro‐1,2,4,5‐tetrazine monohydrochloride (3) in 45‐50% yields along with 3,5‐dimethyl‐1H‐pyrazole (4) and its hydrochloride 5. Oxidation of 3 with sodium perborate produced 3,6‐diamino‐1,2,4,5‐tetrazine (6) in quantitative yield.
Methylation of 2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐ones. A structural determination of anhydro‐5‐aryl‐1,4‐dimethyl‐3‐hydroxy‐1,2,4‐triazolium hydroxides by two dimensional NMR
Authors: Huber Edward W. , Kane John M.
Published: March 2009

The syntheses of 5‐[3‐(n‐butoxy)‐4‐methoxyphenyl]‐4‐methyl‐2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐one (6) and 5‐[3‐(n‐butoxy)‐4‐methoxyphenyl]‐2,4‐dimethyl‐2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐one (7) are reported. The alkylation of6with methyl iodide to yield7also yields anhydro‐5‐[3‐(n‐butoxy)‐4‐methoxyphenyl]‐1,4‐dimethyl‐3‐hydroxy‐1,2,4‐triazolium hydroxide (8). The structures of these products are substantiated using 2D nmr techniques.
Synthesis of 5‐trifluoromethyl‐5,8‐dideazafolic acid and 5‐trifluoromethyl‐5,8‐dideazaisofolic acid
Authors: Singh Shyam K. , Govindan Meledath , Hynes John B.
Published: March 2009

The target folate analogue 5‐trifluoromethyl‐5,8‐dideazafolic acid has been elaborated in a seven‐step reaction sequence beginning with 2‐fluoro‐6‐trifluoromethylbenzonitrile. The bridge‐reversed isomer 5‐trifluoromethyl‐5,8‐dideazaisofolic acid was prepared in six steps using the common intermediate 2,6‐diamino‐3,4‐dihydro‐4‐oxo‐5‐trifluoromethylquinazoline. The key intermediate 2‐amino‐3,4‐dihydro‐4‐oxo‐5‐trifluoromethyl‐quinazoline was prepared using two distinct synthetic routes and the resulting products were found to be identical.
Synthesis of various 5‐substituted uracils
Authors: Peters Dan , Hörnfeldt Anna‐Britta , Gronowitz Salo
Published: March 2009

Several Pd‐catalyzed coupling reactions have been evaluated for the synthesis of 5‐substituted uracils. A convenient reaction, further developed by us, is the Suzuki Pd(0)‐catalyzed coupling between arylboronic acids and aryl bromides or iodides in weakly alkaline medium. However, all attempts to use 5‐bromo‐ or 5‐iodouracil as the aryl halide failed. On the other hand, couplings between 2,4‐di‐t‐butoxy‐5‐bromopyrimidine and various arylboronic acids were successful. In cases when the arylboronic acids were not available, it was better to reverse the coupling functionalities and use 2,4‐di‐t‐butoxy‐5‐pyrimidineboronic acid and arylbromides. A large number of 5‐aryluracils were prepared in this way. They were obtained in almost quantitative yields by dealkylation of the 5‐aryl‐2,4‐di‐t‐butoxypyrimidines. However, a great drawback of these procedures is the highly allergenic properties of 2,4‐dichloro‐5‐bromopyrimidine, which is an intermediate in the synthesis of 2,4‐di‐t‐butoxy‐5‐bromopyrimidine and 2,4‐di‐t‐butoxy‐5‐pyrimidineboronic acid. In order to avoid this intermediate the coupling between 5‐bromo‐2,4‐ditrimethylsilyloxypyrimidine and arylboronic acids were attempted but failed. Also attemptes to prepare 2,4‐di‐trimethylsilyloxy‐5‐pyrimidineboronic acid failed due to migration of a silyl group to the 5‐position upon halogen‐metal exchange. We therefore turned to the use of tin derivatives instead of boronic acids in the coupling reaction, which can be carried out under neutral conditions. Thus 5‐(1‐methyl‐2‐pyrrolyl)uracil, which could not be prepared from 2‐bromo‐1‐methylpyrrole and 2,4‐di‐t‐butoxy‐5‐pyrimidineboronic acid was obtained through the Pd(0)‐catalyzed coupling of 1‐methyl‐2‐trimethylstannylpyrrole and 2,4‐di‐t‐butoxy‐5‐bromopyrimidine followed by dealkylation. However, the great advantage with the tin derivatives was that 5‐bromo‐2,4‐ditrimethylsilyloxypyrimidine could be used in the coupling with aryltin derivatives giving 5‐aryluracils in reasonable yields. We also tried to use unprotected 5‐halouracils in the coupling reactions. We were unsuccessful with the 5‐bromo derivative. However, with 5‐iodouracil coupling was achieved in some cases.
An improved procedure for the preparation of 1‐benzyl‐1H‐1,2,3‐triazoles from benzyl azides
Authors: Cottrell Ian F. , Hands David , Houghton Peter G. , Humphrey Guy R. , Wright Stanley H. B.
Published: March 2009

A procedure for the preparation of substituted 1‐benzyl‐1H‐1,2,3‐triazoles from benzyl azides under very mild conditions is described. The method provides improved yields and extends the scope of the Dimroth Reaction to other types of active methylene compound to those previously used. Benzyl azides react with active methylene compounds in dimethyl sulphoxide catalysed by potassium carbonate at 35–40° to give 1H‐1,2,3‐triazoles usually in good yield. Acetonitrile derivatives gave 5‐amino‐1H‐1,2,3‐triazoles whereas diethyl malonate gave 5‐hydroxy‐1H‐1,2,3‐triazoles. 1H‐1,2,3‐Triazole‐4‐carboxylate esters and 1H‐1,2,3‐triazole‐4‐ketones were obtained from ethyl acetoacetate and β‐diketones respectively. Benzyl methyl ketone reacted to give a 5‐methyl‐4‐phenyl‐1H‐1,2,3‐triazole, but acetone and acetophenone failed to react. Other active methylene compounds which did not react under these reaction conditions included ethyl cyanoacetate, ethyl fluoroacetate and ethyl nitroacetate.
Photoreaction of benzofuroxan
Authors: Hasegawa Minoru , Takabatake Tohru
Published: March 2009

Benzofuroxan 5, upon irradiation using a high pressure mercury lamp with a Pyrex filter in acetonitrile containing a little water, afforded 1H‐azepine‐2,7‐dione 6. The initial stage of this reaction would be formation of a highly reactive intermediate possessing two nitrile oxide functions. On the other hand, when compound 5 was irradiated using a low pressure mercury lamp in acetonitrile containing a little water, it afforded 6H‐furazano[4,5‐c]carbazole 3‐oxide 11 and compound 6. The structure of compound 11 was determined by an X‐ray structural analysis. In the presence of an aromatic hydrocarbon, the formation of compound 11 was decreased and that of compound 6 was increased. Mechanistic studies on the photoreaction suggest that the photosensitized formation of compound 6 with the aromatic hydrocarbon may be carried out by the reabsorption of the fluorescence of it near 365 nm and the presence of it may quench the formation of compound 11.
Pyrazine nucleoside analogs. Synthesis and reactions of some 5‐thio‐substituted pyrazines
Authors: Tuntiwachwuttikul Pittaya , Bardos Thomas J. , Bobek Miroslav
Published: March 2009

5‐Benzylthio‐1,2‐dihydro‐2‐oxopyrazine (8) was prepared from 2‐amino‐5‐bromopyrazine by sequential treatment with sodium thiobenzylate and diazotization. Condensation of the silyl derivative of 8 with a protected 2‐deoxyribofuranosyl chloride gave α and β anomers of 5‐benzylthiopyrazine nucleosides. Reaction of 2,5‐dichloropyrazine 4‐oxide with sodium thiobenzylate followed by hydrolysis gave 5‐benzylthio‐1,2‐dihydro‐2‐oxopyrazine 4‐oxide (16).
Synthesis of vertical‐type bis(pyridodipyrimidines) as a redox catalyst and their autorecycling oxidation of alcohols
Authors: Yamato Hirotake , Nagamatsu Tomohisa , Yoneda Fumio
Published: March 2009

Condensation of bis(3‐methyluracil‐6‐ylamino)alkanes with 6‐chloro‐5‐formyl‐3‐methyluracil or 2,4,6‐trichloropyrimidine‐5‐carbaldehyde in acetic acid gave the respective bis(pyridodipyrimidin‐10‐yl)alkanes (vertical‐type bis(pyridodipyrimidines)). The vertical‐type bis(pyridodipyrimidines) exhibited autorecycling turnover oxidation toward cyclopentanol and l‐menthol to give the corresponding carbonyl compounds.
An alternative preparation of the 2‐dimethylaminomethylene‐1,3‐bis(dimethylimmonio)propane salt from phosphonoacetic acids and some applications in heterocyclic synthesis
Authors: Gupton John T. , Gall John E. , Riesinger Steve W. , Smith Stanton Q. , Bevirt Kathy M. , Sikorski James A. , Dahl Maria L. , Arnold Zdenek
Published: March 2009

An alternative preparation of a 2‐iminovinamidinium salt from phosphonoacetic acids is described along with its application to the synthesis of 5‐formylpyrimidines and masked 4‐formylpyrazoles.
Synthesis of 7‐(alkenyl, cycloalkenyl, and 1,2,3,6‐tetrahydro‐4‐pyridinyl)quinolones
Authors: Kiely John S. , Laborde Edgardo , Lesheski Lawrence E. , Bucsh Ruth A.
Published: March 2009

A series of 1‐cyclopropyl‐1,4‐dihydro‐4‐oxoquinolines was prepared in which the C‐7 position is substituted with a vinyl, a 1‐cyclopentenyl, or a 1,2,3,6‐tetrahydro‐4‐pyridinyl group. These quinolones were synthesized via a palladium‐catalyzed cross coupling of a 7‐quinolyltriflate with an appropriately functionalized vinylstannane.
An improved synthesis of pyrroles from N‐p‐toluenesulfonylglycine esters and α,β‐unsaturated aldehydes and ketones
Authors: Lash Timothy D. , Hoehner Michael C.
Published: March 2009

N‐p‐Toluenesulfonylglycine esters 2 condensed with α,β‐unsaturated carbonyl compounds 1 in the presence of the non‐nucleophilic base DBU to give hydroxypyrrolidines 3. Dehydration with phosphorus oxychloride‐pyridine, followed by DBU mediated elimination of p‐toluenesulfinic acid, gave a series of synthetically useful pyrrole‐2‐carboxylates 5.
Synthesis, stereochemistry and pharmacological activity of rac.‐cis‐tetrahydro‐6‐hydroxy‐7‐(4‐methoxyphenyl)‐1,4‐thiazepin‐5(2H)‐ones
Authors: Mohacsi Erno , O'Brien Jay P. , Todaro Louis J.
Published: March 2009

Reaction of 2‐aminoethanethiol (3) withtrans‐3‐(p‐methoxyplienyl)glycidate (4) gave the rac.‐cis‐1,4‐thiazepinone5and a by‐product6. The structure of5was proven by X‐ray crystallography. The X‐ray data revealed that this compound adopts the chair conformation in the solid state and the heterocyclic ring is sevenmembered. The structure of the by‐product6was elucidated on the basis of spectral data. Compounds9and10were inactive as calcium channel blocking agents.
A comparative study on the synthesis of pyrazolo‐[4,3‐c]quinoline oxides by reductive cyclisations
Authors: Sicker Dieter
Published: March 2009

Alternate routes for the reductive cyclisation of 4‐acetyl‐3‐methyl‐5‐(2‐nitrophenyl)‐1‐phenylpyrazole under different conditions are described. Whereas 3,4‐dimethyl‐1‐phenylpyrazolo[4,3‐c]quinoline 5‐oxide is formed by mild noncatalytic reductions, catalytic and transfer hydrogenation processes cause the diastereoselective formation of cis‐4,11‐dihydro‐3,5‐dimethyl‐1‐phenylpyrazolo[4,3‐c]quinoline 6‐oxide.
Synthesis of pyrrolopyridines (azaindoles)
Authors: Mahadevan Indumathy , Rasmussen Malcolm
Published: March 2009

Improved, convenient, and reliable routes for the synthesis of 4‐, 5‐, 6‐, and 7‐azaindole, 7‐methyl‐4‐azaindole, 7‐methyl‐6‐azaindole, and the hitherto unreported 7‐amino‐4‐azaindole are described. The syntheses have been accomplished either by significant modifications to established procedures or by new methods which afford the compounds in improved yields.
Synthesis of 7‐methyl‐4,6,6a,7,10,10a‐hexa‐hydroindolo[4,3‐fg]quinazoline derivatives
Authors: Mantegani Sergio , Bandiera Tiziano , Brambilla Enzo , Traquandi Gabriella
Published: March 2009

The synthesis of a series of compounds indolo[4,3‐fg]quinazoline related to ergoline (indolo[4,3‐fg]quinoline) is reported. The key step of the synthetic sequence is the ring cleavage of the ketone IV. The stereochemistry of the chiral centers is established by the chirality of dihydrolysergic acid I.
Inverted and suppressed direct response HMQC‐TOCSY spectra ‐ a convenient method of spectral editing
Authors: Martin Gary E. , Spitzer Timothy D. , Crouch Ronald C. , Luo Jiann‐Kuan , Castle Raymond N.
Published: March 2009

HMQC‐TOCSY spectra provide a convenient means of establishing proton‐proton connectivities in congested spectra of complex aromatic heterocycles. Advantage is taken of the greater dispersion of the 13C nmr spectrum to circumvent overlap which would preclude spectral interpretation through the usual COSY spectrum. A recently reported method for inverting direct responses (IDR) in HMQC‐TOCSY spectra is demonstrated for [1]benzothieno[2,3‐c]naphtho[2,1‐g]quinoline. A modification of the IDR‐HMQC‐TOCSY method is also demonstrated which is capable of fully suppressing direct responses (SDR) without resorting to the timing of the onset of decoupling as in the original report of the HMQC‐TOCSY experiment. SDR‐HMQC‐TOCSY has the further advantage of allowing the use of higher levels of digitization in F2 than can be attained when broadband heteronuclear decoupling is employed.
Synthesis of 5‐fluoro‐2‐methyl‐3‐(2‐trifluoromethyl‐1,3,4‐thiadiazol‐5‐yl)‐4(3H)‐quinazolinone and related compounds with potential antiviral and anticancer activity
Authors: Párkányi Cyril , Yuan Hui Liang , Strömberg Bo H. E. , Evenzahav Ariella
Published: March 2009

The synthesis of ten new substituted 1,3,4‐thiadiazolyl‐4(3H)‐quinazolinones 8–11, 13, 17, and 20–23 is reported. Compounds 8–11 were prepared by condensation of 5‐fluoro‐2‐methyl‐3,1‐benzoxazin‐4‐one (3) and 5‐substituted 2‐amino‐1,3,4‐thiadiazoles 4–7. Compound 13 was obtained by condensation of 5‐fluoro‐2‐methyl‐3,1‐benzoxazin‐4‐one (3) with DL‐α‐amino‐ϵ‐caprolactam (12). Compound 17 was synthesized by condensation of 6‐bromo‐2‐methyl‐3,1‐benzoxazin‐4‐one (16) and 2‐amino‐5‐t‐butyl‐1,3,4‐thiadiazole (5). Compounds 20–23 were obtained by condensation of 5‐chloro‐6,8‐dibromo‐2‐methyl‐3,1‐benzoxazin‐4‐one (19) and 5‐substituted 2‐amino‐1,3,4‐thiadiazoles 4–7, respectively. The substituted 3,1‐benzoxazin‐4‐ones 3, 16, and 19 were obtained in good yield by refluxing the appropriate anthranilic acid, 1,15, and 18 with acetic anhydride (2).
Synthesis of pyrido[1′,2′:1,2]imidazo[4,5‐b]quinoxalines
Authors: Tanaka Kiyoshi , Takahashi Hideki , Takimoto Kozo , Sugita Masahiko , Mitsuhashi Keiryo
Published: March 2009

Synthesis of pyrido[1′,2′:1,2]imidazo[4,5‐b]quinoxalines by the facile cyclizations of 2,3‐dichloroquinoxalines with 2‐aminopyridines and of 2‐amino‐3‐chloroquinoxalines with various substituted pyridines is described.
Investigation of the synthesis and analgesic activity of 1‐substituted 4‐(propananilido)perhydroazepines
Authors: Deruiter Jack , Andurkar Shridhar , Riley Thomas N. , Walters Donald E. , Noggle F. Taylor
Published: March 2009

Methods are explored to enhance the efficiency and versatility of the synthesis of the 1‐substituted 4‐(propananilido)perhydroazepine analgesics. The modified synthesis begins with ring expansion of 1‐carbethoxy‐4‐piperidinone3with ethyl diazoacetate and boron trifluoride to yield 1,5‐biscarbethoxyperhydroazepin‐4‐one4. Selective hydrolysis of4followed by decarboxylation provides 1‐carbethoxyperhydroazepin‐4‐one6. Reductive amination of6with aniline affords the 4‐anilino intermediate7which is treated with propionic anhydride to give 1‐carbethoxy‐4‐(propananilido)perhydroazepine18. Selective cleavage of the 1‐carbethoxy group of 18 was accomplished with trimethylsilyliodide to yield the versatile intermediate 4‐(propananilido)‐perhydroazepine 19. Treatment of 19 with styrene oxide afforded the 1‐[2‐(1‐hydroxy‐1‐phenyl)ethyl] derivative1cwhich, in the tail‐flick assay, displays greater analgesic potential than previously reported members of this series.
The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 10. Synthesis and structure determination of naphtho[1′,2′:4,5]thieno[3,2‐a]‐4,7‐phenanthroline
Authors: Musmar M. J. , Zektzer Andrew S. , Castle Raymond N. , Kent Dalley N.
Published: March 2009

Naphtho[1′,2′:4,5]thieno[3,2‐a]‐4,7‐phenanthroline, a novel hexacyclic ring system has been synthesized in four steps. The 1H and 13C nmr assignments have been made using two‐dimensional nmr techniques. The tertiary helical structure was determined by X‐ray crystallographic analysis.
An evaluation of hofmann and cope elimination routes to (±)‐2‐n‐propylthietane
Authors: Woolhouse A. D. , Gainsford G. J. , Crump D. R.
Published: March 2009

A synthetic route to (±)‐2‐n‐propylthietane 1 that utilises a silver oxide‐induced Hofmann elimination is described together with an evaluation of the potential of a Cope elimination as an alternative and more cost‐effective route to 1. Some chemistry of the isomeric intermediate thiete sulfones 5 and 12 from each of these respective eliminations is presented.
Synthesis of thieno[2,3‐d]pyrimidines from 4,6‐dichloropyrimidine‐5‐carbaldehydes
Authors: Clark J. , Shahhet M. S. , Korakas D. , Varvounis G.
Published: March 2009

Several thieno[2,3‐d]pyrimidines have been prepared by intramolecular cyclisation of 6‐(substituted methylthio)‐5‐pyrimidinecarbaldehyde and carbonitrile intermediates derived from 6‐chloropyrimidine‐5‐carbaldehydes and 5‐carbonitriles and methyl thioglycolate or 5‐formylpyrimidine‐4‐(3H)‐thiones and appropriate α‐halogeno compounds. Thienopyrimidines 18 and 5c were nitrated to the corresponding nitro compounds 23 and 24. Hydrolysis at position 4 of compound 18 also occurred during nitration. The ester 5g was hydrolysed in base to the acid 25.
Synthesis of 8‐dipropylamino‐7,8,9,10‐tetrahydrophenanthridines as potential serotoninergic agonists
Authors: Castan Florence , Bigg Dennis C. H.
Published: March 2009

A number of 8‐dipropylamino‐7,8,9,10‐tetrahydrophenanthridines have been prepared as analogs of the known serotoninergic agonist 8‐hydroxy‐2‐(dipropylamino)tetralin (8‐OH‐DPAT) and their affinity for the 5‐HT1Areceptor subtype evaluated by radioligand binding assay.
Synthesis of some benzo[h]quinoline derivatives
Authors: Janin Yves L. , Bisagni Emile , Carrez Danièle
Published: March 2009

Reaction between 6‐methoxy‐1‐tetralone, methyl propiolate and an ammonia‐saturated methanolic solution led to 5,6‐dihydro‐8‐methoxybenzo[h]quinolin‐2(1H)‐one in good yields. Subsequent aromatization, chlorination, substitution and demethylation enabled us to prepare 2‐amino‐substituted benzo[h]quinoline derivatives. These compounds, which are structurally related to the antitumor benzo[c]phenanthridine alkaloids by deletion of a ring, were tested on cultured murine lymphoblastic leukaemia cells (L1210). Results showed that they are devoid of cytotoxicity.
Synthesis, structural, conformational and pharmacological study of new fentanyl derivatives of the camphidine system
Authors: Rico B. , Gálvez E. , Izquierdo M. L. , Arias M. S. , Orjales A. , Berisa A. , Labeaga L.
Published: March 2009

A series ofN‐phenethyl‐8‐β‐amidocamphidines4a‐f(3‐phenethyl‐8‐β‐(N‐arylamido)‐3‐azabicyclo‐[3.2.1]octane) has been designed, synthesized and stereochemically characterized as semirigid analogous of the 4‐anilidopiperidine analgesics in an attempt to study the influence of certain stereochemical factors on analgesia in this class of compounds. In deuteriochloroform and deuteriobenzene solution, compounds4a‐fdisplay the same preferred conformation. The cyclopentane and piperidine rings adopt an envelope and distorted chair conformation respectively flattened at N‐3, with the N and C‐8 substituents in equatorial and axial positions with respect to the piperidine ring.

In vivopharmacological testing demonstrated that compounds4a‐fwere inactive in the analgesic test, with the exception of compound4fwhich showed an ED50of 250 mg/kg p.o.
New method of synthesis of 1,5‐benzodiazepin‐2‐ones from 4‐hydroxycoumarin
Authors: Hamdi Maǎmar , Grech Odile , Sakellariou Reine , Spézale Vincent
Published: March 2009

A new method of synthesis of 1,5‐benzodiazepine‐2‐ones, from 4‐hydroxycoumarin and substituted 1,2‐phenylenediamines by heating in xylene or acetic acid‐ethanol, is reported.
A convenient method for regioselective C‐5 halogenation of 4(3H)‐oxo‐7H‐pyrrolo[2,3‐d]pyrimidines
Authors: Barnett Charles J. , Kobierski Michael E.
Published: March 2009

N‐7, O‐Disilylation of 4(3H)‐oxo‐7H‐pyrrolo[2,3‐d]pyrimidines provides a convenient method for activation of these compounds toward regiospecific halogenation at C‐5. The sequence is conveniently carried out without isolation of the silylated derivatives and desilylation is spontaneous upon addition of water to the reaction mixture.
Studies on pyrazines. Part 28. Deoxydative acetoxylation of pyrazine N‐oxides
Authors: Sato Nobuhiro , Miwa Naoko , Suzuki Hiroko , Sakakibara Tohru
Published: March 2009

Deoxydative acetoxylation of 3‐methoxy‐, 3‐phenyl‐, 3‐methyl‐, 3‐chloro‐, and 3‐methoxycar‐bonylpyrazine 1‐oxides furnished predominantly 2‐acetoxy‐6‐substituted pyrazines, some of which were more selectively prepared by addition of zinc bromide and triethylamine to the reaction. Regioselectivity of the acetoxylation is discussed based upon heat of formation by AMI and AMI‐COSMO for all possible isomers of each set.
The synthesis of azatryptophane derivatives
Authors: Svete Jurij , Stanovnik Branko , Tiŝler Miha
Published: March 2009

Optically active and racemic isomers of aspartic acid (1) were transformed into the corresponding N‐trifluoroacetyl‐5‐bromo‐4‐oxonorvaline methyl esters (6, R = Me) and N‐trifluoroacetyl‐3‐formylalanine methyl esters 13, which were used as starting compounds in the synthesis of β‐heteroaryl substituted‐α‐amino acids.
A new procedure for the synthesis of 4H‐pyrazolo[1,5‐c][1,3,5]thiadiazine‐4‐thiones
Authors: Vicentini C. B. , Veronese A. C. , Guarneri M. , Manfrini M. , Giori P. , Guccione S.
Published: March 2009

Thiation of N‐(1‐tert‐butyl‐3‐methylpyrazol‐5‐yl)carboxamides 2 with the Lawesson reagent afforded the corresponding thiocarboxamides 3. Heating of 3 in formic acid gave the N‐dealkylated thiocarboxamides 4 which were cyclized into 4H‐pyrazolo[1,5‐c][1,3,5]thiadiazine‐4‐thiones 5 by treatment with thiophosgene.
Novel pyranopyridine derivatives from an enaminone
Authors: Löwe Werner , Braun Beate , Müller Bärbel
Published: March 2009

The pyranopyridine derivatives 2 and 15B were synthesized from enaminone 1 and hydroxylamine in the presence of 2N and 1N aqueous sodium hydroxide solutions, and consecutive reactions with these compounds are described.
Diazine‐substituted tert‐butylureas and tert‐butylthioureas and a convenient access to the related carbodiimides
Authors: Heinisch Gottfried , Matuszczak Barbara , Pürstinger Gerhard , Rakowitz Dietmar
Published: March 2009

An efficient procedure for the preparation of diazine‐substituted urea and thiourea derivatives 3a‐c, 5a‐c is proposed. On attempts to prepare the related S‐methylisothioureas 6a‐c under phase‐transfer conditions smooth conversion into carbodiimides 7a‐c was found to occur.
The methylation, oxidation and crystallographic characterization of imidazole derivatives
Authors: Vampa Gabriella , Benvenuti Stefania , Severi Fabio , Malmusi Luca , Antolini Luciano
Published: March 2009

Compounds 2, 3 and 4 were synthesized and the crystal and molecular structures of 1 and 4 were determined. An hptlc technique for studying the methylation rate of 1 and the oxidation rate of 2 was applied.