bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel heterocycles. Synthesis of 2,3‐dihydro‐6‐methyl‐2‐phenyl‐4H,6H‐pyrano[3,2‐c][2,1]benzothiazin‐4‐one 5,5‐dioxide and related compounds
Authors: Coppo Frank T. , Fawzi Maged M. 
Published: March 2009

AbstractThe reaction of 2‐chloro‐4‐(methylsulfonyl)benzoyl chloride (5) with 1‐methyl‐1H‐2,1‐benzothiazin‐4‐(3H)‐one 2,2‐dioxide (4) gave the O‐benzoyl compound, 1‐methyl‐2,2‐dioxido‐1H‐2,1‐benzothiazin‐4‐yl 2‐chloro‐4‐(methylsulfonyl)benzoate (6), which rearranged to give the C‐benzoyl isomer, [2‐chloro‐4‐(methylsulfonyl)phenyl] (4‐hydroxy‐1‐mefhyl‐2,2‐dioxido‐1H‐2,1‐benzothiazin‐3‐yl)methanone (7). The O‐cinnamoyl compound 13 that resulted from the addition of 2,4‐dichlorocinnamoyl chloride (11) to compound 4 rearranged to give the C‐cinnamoyl compound, 3‐(2,4‐dichlorophenyl)‐1‐(4‐hydroxy‐1‐methyl‐2,2‐dioxido‐1H‐2,1‐benzothiazin‐3yl)‐2‐propen‐1‐one (15). On the other hand, 1‐methyl‐2,2‐dioxido‐1H‐2,1‐benzothiazin‐4‐yl 3‐phenyl‐2‐propenoate (19) (from cinnamoyl chloride (17) and compound 4) rearranged to give 2,3‐dihydro‐6‐methyl‐2‐phenyl‐4H,6H‐pyrano[3,2‐c][2,1]benzothiazin‐4‐one 5,5‐dioxide (21), an example of a hitherto unknown ring system. Additional examples of this novel heterocycle were prepared from 1‐methyl‐7‐(trifluoromethyl)‐1H‐pyrido[2,3‐c][1,2]thiazin‐4(3H)‐one 2,2‐dioxide (23) and 1‐methyl‐1H‐thieno[3,2‐c][1,2]thiazin‐4(3H)‐one 2,2‐dioxide (8).
Cyclocondensation of 6‐acetyl‐4,7‐dihydro‐5‐methyl‐7‐phenyl[1,2,4]triazolo[1,5‐a]pyrimidine with hydroxylamine and hydrazine
Authors: Desenko Sergey M. , Komykhov Sergey A. , Orlov Valery D. , Meier Herbert 
Published: March 2009

AbstractThe cyclocondensation of 6‐acetyl‐4,7‐dihydro‐5‐methyl‐7‐phenyl[1,2,4]triazolo[1,5‐a]pyrimidine (3) with hydroxylamine or hydrazine leads to 3a,4,9,9a‐tetrahydro‐3,9a‐dimethyl‐4‐phenylisoxazolo‐[5,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine (4a) and 3a,4,9,9a‐tetrahydro‐3,9a‐dimethyl‐4‐phenyl‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine (4b), respectively. In the presence of methanolic hydrogen chloride, 4b undergoes a cleavage of the pyrimidine ring to yield (5‐amino‐1,2,4‐triazol‐1‐yl)(3,5‐dimethylpyrazol‐4‐yl)phenylmethane (5). The structure determination of the compounds obtained is based on 1H and 13C nmr spectra including NOE measurements.
Preparation of 1,2‐disubstituted‐3‐hydroxy‐4(1H)‐quinolinones and the influence of substitution on the course of cyclization
Authors: Hradil Pavel , Hlaváč Jan , Lemr Karel 
Published: March 2009

AbstractSynthesis of 1,2‐disubstituted‐3‐hydroxy‐4(1H)‐quinolinones by the cyclization of N‐substituted phenacyl or acetonyl anthranilates is described. Two methods were employed for cyclization of anthranilates. Heating in polyphosphoric acid has a wide scope of applicability. The thermal cyclization in boiling N‐methylpyrrolidone is limited by steric effect.
A simple one step synthesis of new 3,5‐disubstituted‐4‐amino‐1,2,4‐triazoles
Authors: Bentiss Fouad , Lagrenée Michel , Traisnel Michel , Mernari Bouchaib , Elattari Hassan 
Published: March 2009

AbstractA number of symmetrically 3,5‐disubstituted 4‐amino‐1,2,4‐triazoles have been prepared by the reaction of aromatic nitriles with hydrazine dihydrochloride or sulfate with an excess of hydrazine hydrate in ethyl ene or diethylene glycol under a nitrogen atmosphere. The structures of the new triazoles derivatives were confirmed by analytical and spectral data.
Fused 1,2‐dithioles. IV. Synthesis and reactions of 1,2‐dithiole s‐oxides
Authors: Schachtner Josef Emmeram , Zoukas Thomas , Stachel Hans‐Dietrich , Polborn Kurt , Nöth Heinrich 
Published: March 2009

Abstract1,2‐Dithiolopyrrolones and their heterologues of type 1 are resonance stabilized systems displaying a high dipole moment. Upon oxidation with organic peracids compounds 2, 5, 15a, 16a, 20a and 25a gave the corresponding S(2)‐oxides and, depending on substituents, in some cases the S(2)‐ and S(1)‐dioxides. The S(2)‐monoxides showed a proclivity to disproportionation and were easily reduced to dithioles with symme trical dimethylhydrazine. From S(2)‐oxides and several primary amines bicyclic isothiazole‐S‐oxides were obtained (S/N‐exchange reaction). From the N‐unsubstituted isothiazole S‐oxide 10e the N‐hydroxyisothiazole 9d was synthesized by an aza‐Pummerer‐type rearrangement. The assumption is made that S(2)‐oxides may be biologically important as active metabolites of pyrrothines and analogues of type 1 in their action as antibacterials and antimycobacterials.
9,9′‐Thiobis‐(1,2,3,4,7,8‐hexahydro‐7‐methyl‐6H‐pyrimido[1,6‐a]pyrimidine‐6,8‐dione)
Authors: Šimo Ondrej , Rybár Alfonz , Alföldi Juraj , Pätoprstý Vladimír 
Published: March 2009

AbstractThe 6‐(3‐hydroxypropylamino)‐3‐methylpyrimidine‐2,4‐dione (1) did not afford the expected 6‐(3‐chloro‐propylamino)‐ derivative on reaction with thionyl chloride, but, instead, the pyrimidine rings were joined via a sulfur bridge to give 9,9′‐thiobis(1,2,3,4,7,8‐hexahydro‐7‐melnyl‐6H‐pyrimido[1,6‐a]pyrirnidine‐6,8‐dione) (3). An identical 9,9′‐thiobis‐ derivative 3 was obtained when reacting thionyl chloride with 1,2,3,4,7,8‐hexahydro‐7‐methyl‐6H‐pyrimido[1,6‐a]pyrimidine‐6,8‐dione (4). We suppose the sulfoxide‐ derivative 2 to be the intermediate of both routes: it underwent reduction to the final sulfide 3 in excess thionyl chloride.
The solid‐state michael addition of indole to 4‐arylidene‐3‐methyl‐5‐pyrazolone
Authors: Li Xiao‐Liu , Wang Yong‐Mei , Matsuura Teruo , Meng Ji‐Ben 
Published: March 2009

AbstractThe Michael addition reactions of indole to 4‐arylidene‐3‐methyl‐1‐phenyl‐5‐pyrazolone 1 were investigated in the solid state, by which a series of new compounds, 1‐aryl‐1‐(3‐indolyl)‐1‐(3′‐methyl‐1′‐phenyl‐5′‐pyrazolon‐4′‐yl)methanes 2, were easily obtained. This provides a feasible method of preparing novel compounds containing two heterocyclic groups at the same carbon.
A new approach to the synthesis of benzofuro[3,2‐b]quinolines, benzothieno[3,2‐b]quinolines and indolo[3,2‐b]quinolines
Authors: Rádl Stanislav , Konvička Petr , Váchal Petr 
Published: March 2009

AbstractTreatment of 2‐hydroxy‐, 2‐mercapto‐, and 2‐ethoxycarbonylamino‐benzonitriles 12 with 2‐fluoro‐ or 2‐nitrophenacylbromides 13 under alkaline conditions provided the corresponding benzofuran, benzothiophene, and indole intermediates 10, respectivelly. Nucleophilic cyclization of these compounds led to the corresponding tetracyclic quinolinones 7a, 7b, and 3. Denitrocyclization reaction of compounds 10 (R = NO2) was found especially useful. Compounds 7a, 7b, and 3 were converted to their chloro derivatives 14a‐c, which were reduced with hydrogen and a catalyst to the corresponding compounds 8a, 8b, and 2. The presented pathway represents a new method of preparation of quindoline 2 and its O and S analogs 8. Chloro derivatives 14 are reactive enough to provide the corresponding methoxy derivatives 15 and dimethylamino derivatives 16. Methylation of compounds 7a and 7b with iodomethane providing mixtures of major N‐methyl derivatives 17 and minor O‐methyl derivatives 15 were also studied.
Synthesis of benzo[b]thieno‐ and benzo[b]furano‐[2,3‐a]pyrrolo[3,4‐c]carbazole‐5‐, ‐7‐ and ‐5,7‐dione
Authors: Hudkins Robert L. , Johnson Neil W. 
Published: March 2009

AbstractBenzo[b]thieno[2,3‐a]pyrrolo[3,4‐c]carbazoles and benzo[b]furano[2,3‐a]pyrrolo[3,4‐c]carbazoles were prepared from 2‐(2‐benzo[b]thieno)‐ (8) and 2‐(2‐benzo[b]furano)‐3‐[3‐(2,5‐dioxo‐lH‐pyrrolidinyl)]indole (9) by a palladium(II)acetate/tetrachloro‐1,4‐benzoquinone oxidative A‐E ring closure.
Synthesis of 3‐Carboxylic derivatives of 1,5‐benzodiazepines
Authors: Mansour O. , Szymonski B. , Morand J. M. , Cussac M. , Thomasson F. 
Published: March 2009

AbstractA series of 3‐carboxylic derivatives of disubstituted 1,5‐benzodiazepines(5–9)was synthesized by hetero‐cyclisation from 1,2‐diaminobenzene(1)with dibenzoylmethane(2)followed by bromination on position 3 and by introduction of the carboxylic group or introduction of the malonic moiety. Reduction of the hetero‐cycle gave the perhydro derivative diethyl (2,4‐diphenyl‐1,2,4,5‐tetrahydro‐3H‐1,5‐benzodiazepin‐3‐yl)malonate(9).
Synthesis and characterization of new heterocyclic derivatives by oxidation of 1‐amino‐2‐methylindoline
Authors: Peyrot L. , Elkhatib M. , Vignalou J. R. , Metz R. , Elomar F. , Delalu H. 
Published: March 2009

Abstract1‐Amino‐2‐methylindoline is a precursor used in the synthesis of antihypertension drugs. It reacts with monochloramine to lead to the formation of 1‐amino‐2‐methylindole and azo(2‐methyl)indoline. These new products have been isolated and characterized by microanalysis, uv, gc/ms, ir, and 1H/13C nmr. The reaction leads to the transient formation of an indolic aminonitrene. 1‐Amino‐2‐methylindole formation proceeds in strongly alkaline medium by rearrangement of a diaziridine intermediate. In neutral or slightly alkaline medium, one obtains a precipitate of tetrazene type (‐N‐N=N‐N‐), the azo(2‐methyl)indoline. The study of the thermochemical properties shows that tetrazene decomposes towards 150 °C to give the 1,1′‐bi(2‐methyl)indoline. The stability of the starting reagents and products was the subject of a systematic investigation. A reaction mechanism is proposed.
Synthesis of new 5‐substitutedbenzo[b]thiophene derivatives
Authors: Pérez‐Silanes S. , Martínez‐Esparza J. , Oficialdegui A. M. , Villanueva H. , Orúas L. , Monge A. 
Published: March 2009

AbstractPrevious works of our group have dealt with the synthesis of 1‐(aryl)‐3‐[4‐(aryl)piperazin‐1‐yl]propane derivatives in the search for new and efficient antidepressants with a dual mode of action: serotonin reuptake inhibition and 5‐HT1A receptor afinity [1‐4]. From these studies we concluded that the 3‐[4‐(aryl)piperazin‐1‐yl]‐1‐(benzo[b]thiophen‐3‐yl)propane derivatives led to the best results. The continuation of this research project required the preparation of some new 3‐acyl‐5‐substituted benzo[b]thiophenes with a wide variety of substituents at the 5 position, ranging from nitro to hydroxyl derivatives. To obtain these derivatives we acylated the corresponding 5‐substituted benzo[b]thiophenes when it was possible.
Easy access to medium rings by entropy/strain reduction, Part 3. Competition between dihydroazepine and enamine formation in reaction of tetrahalosubstituted dibromides with primary amines
Authors: Walsh James G. , Gilheany Declan G. 
Published: March 2009

AbstractThe reaction of Z,Z‐2,3,4,5‐tetrahalo‐2,4‐dien‐1,6‐dibromides (3, R1 ‐ R4 = Cl, Br) with primary amines in the presence of potassium carbonate leads to both the dihydroazepines 4 and secondary enamines 5. The formation of enamine is suppressed with toluene sulfonamide as nitrogen source. (2Z,4Z)‐2,3,4,5‐Tetrabromo‐hexa‐2,4‐diene‐1,6‐diol (2, R1 ‐ R4 = Br) is atropisomeric in solution.
Synthesis of 2‐(2‐, 3‐, and 4‐pyridyl)benzoxazoles by the reaction of phenolic schiff bases with thianthrene cation radical
Authors: Park Myeong Soon , Ha Park Koon , Jun Kun , Shin Seung Rim , Oh Sea Wha 
Published: March 2009

Abstract2‐(2‐, 3‐, and 4‐Pyridyl)benzoxazole derivatives were prepared in excellent yields by the oxidative cyclization of phenolic Schiff bases with thianthrene cation radical perchlorate in the presence of 2,6‐di‐tert‐butyl‐4‐methylpyridine.
Facile one‐pot syntheses of new polyfunctional pyrazolyl substituted and pyrazolofused pyridines
Authors: El Latif Fawi M. Abd , El Rady Eman A. , Döupp Dietrich 
Published: March 2009

AbstractEthyl 2‐cyano‐3‐(5‐chloro‐1,3‐diphenylpyrazol‐4‐yl)acrylate (1) undergoes both conjugate addition of a number of methylene‐active ethanenitriles and direct addition of other active methylene donors to the cyano carbon atom. These additions are the starting events of cascades of subsequent reactions eventually forming (i) novel polyfunctional pyrazolyl‐substituted monocyclic pyridines (4a,band6), (ii) 1,3‐benzothiazole and benzimidazole‐fused pyridines (11, 13) and (iii) pyrazolo[5,4‐b]pyridines (19b, 20) in one‐pot reactions in ethanolic solution containing catalytic amounts of piperidine.
Regioselective synthesis of ethyl pyrazolecarboxylates from ethyl 3‐[(dimethylamino)methylidene]pyruvate and diethyl 3‐[(dimethylamino)methylidene]‐2‐oxosuccinate. Isolation of ethyl 4,5‐dihydro‐1‐heteroaryl‐5‐hydroxy‐1H‐pyrazole‐5‐carboxylates as stable intermediates in the pyrazole ring formation
Authors: Hanzlowsky Andrej , Jelenčič Blanka , Rečnik Simon , Svete Jurij , Golobič Amalija , Stanovnik Branko 
Published: March 2009

AbstractReactions of ethyl 3‐[(E)‐(dimethylamino)methylidene]pyruvate (3) and 3‐[(dimethylamino)methyl‐idene]‐2‐oxosuccinate (4) with hydrazine monohydrochloride (5a) and (hetero)arylhydrazines (5b‐i) afforded, regioselectively, 1‐substituted ethyl 1H‐pyrazole‐5‐carboxylates 9a‐f and diethyl 1H‐pyrazole‐3,4‐dicarboxylates, 11a‐i, respectively. Upon treatment of 3 with pyridazinylhydrazines 5d‐f, the stable intermediates, 1‐substituted ethyl 4,5‐dihydro‐5‐hydroxy‐1H‐pyrazole‐5‐carboxylates 8d‐f, were isolated. Treatment of compounds 8d‐f in acetic acid under reflux furnished the pyrazoles 9d‐f. On the other hand, reaction of 3 with N,N′‐dimethylhydrazine (51) gave ethyl 1‐methyl‐1H‐pyrazole‐3‐carboxylate (14). The structures of compounds 3, 4, 14 were determined by nmr (noesy and hmbc techniques), while the structures of compounds 8f, 9f, and 11e, f were determined by X‐ray diffraction.
Cyanomethylation of anthranilic acid
Authors: Mitchell Miguel O. , Hurley Ashley R. 
Published: March 2009

AbstractAnthranilic acid reacts with chloroacetonitrile and N,N‐diisopropylethylamine in DMF to yield 3‐imino‐2,3‐dihydro‐4,1‐benzoxazepin‐5(1H)‐one (1) as the only reaction product. Also known as Ashley's fluorescer, compound 1 is fluorescent and binds to calcium carbonate, including the calcium carbonate‐rich antennae of Daphnia pulex, the water flea.
2,4‐Dinitroimidazole: Microwave assisted synthesis and use in synthesis of 2,3‐dihydro‐6‐nitroimidazo[2,1‐b]oxazole analogues with antimycobacterial activity
Authors: Bhaumik Kankan , Akamanchi K. G. 
Published: March 2009

Abstract2,4‐Dinitroimidazole (2,4‐DNI), an important starting material for nitroimidazooxazole and nitroimidazooxazine types of antitubercular agents was synthesized by rearrangement of 1,4‐dinitroimidazole (1,4‐DNI) under microwave irradiation. Various new nitroimidazooxazoles analogues were prepared using 2,4‐DNI and were tested preliminarily against Mycobacterium tuberculosis, H37Rv strain. Some were found to be active.
Simple, efficient, high yield syntheses of substituted and unsubstituted 5‐benzoylbarbituric acids, and their corresponding schiff base phenylhydrazones
Authors: Jursic Branko S. , Neumann Donna M. , Bowdy Katharine L. , Stevens Edwin D. 
Published: March 2009

AbstractPreparation procedures for biologically important benzoylbarbiturates are presented. Several procedures are optimized to cover the preparations of a wide variety of substituted 5‐benzoylbarbiturates. To further explore the biological importance of these compounds, multi‐ gram preparation procedures for nitrophenyl‐hydrazones of benzoylbarbiturates and their corresponding salts with organic amines are discussed. It is demonstrated that these compounds can exist in several tautomeric forms and that the equilibrium in solution can be changed by temperature as well as by the pH of the solution. X‐ray structural analysis performed on one of the nitrophenylhydrazones of benzoylbarbiturates fully agrees with the presented spectroscopic studies. AMI semi‐empirical studies show that the enol form is preferred in the gas phase of benzoylbarbiturates over the keto form, which was also confirmed by NMR spectroscopic studies with chloroform as the solvent. Furthermore, AMI computed structural and electronic properties of the dinitrophenylhydrazone of 4‐hydroxybenzoylbarbiturate compared favorably with the X‐ray determined structure.
Alkylation of 2‐pyridinones: Synthesis of novel acyclonucleosides
Authors: El‐Essawy Farag A. , Khattab Ahmed F. 
Published: March 2009

AbstractThis paper presents the synthesis of some novel acyclonucleosides containing 2‐pyridinones and 2‐hydroxyethoxymethyl, 2,3‐dihydroxy‐propyl side chain. The tosylate of these nucleosides analogues could be modified to azido derivatives. Also, acyclonucleosides with 1‐ethoxymethyl, 1‐benzyloxymethyl, 1‐methylthiomethy 1 and 2‐hydroxyethyl side chains have been investigated. The O‐alkylated pyridine derivatives were obtained during most reactions.
Transformation reactions of the betti base analog aminonaphthols
Authors: Szatmári István , Hetényi Anasztázia , Lázár László , Fülöp Ferenc 
Published: March 2009

AbstractBy means of simple or domino ring‐closure reactions of 1‐(α‐aminobenzyl)‐2‐naphthol (Betti base: 1), 1‐aminomethyl‐2‐naphthol (2) and 2‐(α‐aminobenzyl)‐1‐naphthol (reverse Betti base: 3) with phosgene, ethyl benzimidate, 2‐carboxybenzaldehyde, levulinic acid, salicylaldehyde/formalin or salicylaldehyde/acetaldehyde, naphth[1,2‐e][1,3]oxazine and naphth[2,1‐e][1,3]oxazine derivatives were prepared. All of the nitrogen‐bridged polycyclic derivatives of 1 and 3 containing a number of centers of asymmetry were formed with nearly complete diastereoselectivity. Considerable differences were observed in the ring‐closing abilities of the unsubstituted and phenyl‐substituted aminonaphthols 1 and 2 and of the regioisomeric compounds 1 and 3.
Cyclocondensation reaction of heterocyclic carbonyl compounds . The direction of competitive cyclocondensation between carbonyl groups of 6‐azauracile and 1,2‐dihydro‐quinoxalin‐2‐one cycles
Authors: Buchtík Roman , Hlaváč Jan , Slouka Jan , Fryčák Petr 
Published: March 2009

AbstractIn the article the study of cyclocondensation of 3‐[2‐amino‐3‐(3,5‐dioxo‐2,3,4,5‐tetrahydro[1,2,4]‐triazme‐6‐yl)phenyl]‐2,3‐dihydro‐quinoxalin‐2‐one 5 is described and it was found, that the reaction does not proceed by both possible directions, but only cyclization with the carbonyl group of 6‐azauracile cycle proceeds. The 6‐(3‐oxo‐3,4‐dihydro‐quinoxaline‐2‐yl)‐4H‐2,3‐dihydro[1,2,4]triazino[5,6‐b]indol‐3‐one 6 was formed in this way. This course of cyclocondensation was confirmed by the fact, that the product 6, mentioned above, is quite different from isomeric compound 7, prepared unambiguously by condensation of 7‐(6‐azauracile‐5‐yl)isatine 8 with o‐phenylenediamine.
Synthesis of 5‐phenyl‐5,6,7,8‐tetrahydro‐1,6‐naphthyridines and 5‐phenyl‐6,7,8,9‐tetrahydro‐5H‐pyrido[3,2‐c]azepines as potential D1 receptor ligands
Authors: Hussenether Thomas , Troschütz Reinhard 
Published: March 2009

AbstractA new access to 5‐phenyl‐5,6,7,8‐tetrahydro‐1,6‐naphthyridines25a‐28a(n=1) and 5‐phenyl‐6,7,8,9‐tetrahydro‐5H‐pyrido[3,2‐c]azepines25b‐28b(n=2) has been developed by first preparing the functional pyridine moiety followed by intramolecular cyclization forming the partially reduced ring.
The examination of the Book of Kells using micro‐Raman spectroscopy
Authors: Bioletti Susan , Leahy Rory , Fields John , Meehan Bernard , Blau Werner 
Published: March 2009

AbstractThe Book of Kells, Trinity College Dublin MS 58, is one of Ireland's greatest cultural treasures, and as such all aspects of its production have attracted academic attention. Until recently, studies of its dyes and pigments have relied exclusively on techniques such as visual and optical microscopic and spectroscopic examination, and comparison of the appearance of the pigment with specimens prepared using ancient or medieval recipes. These studies have yielded interesting results, but, due to the limitations of the examination techniques, they have remained incomplete and somewhat speculative. This article presents the results of a pigment analysis that took place between 2004 and 2006 using micro‐Raman spectroscopy. In total, 681 sites over the 4 volumes of the Book of Kells were analysed using 2 separate laser wavelengths (632.8 and 532 nm), making this the most extensive Raman spectroscopic investigation of a single medieval manuscript. In this article several pigments are identified, in particular, blue (indigo), red–orange (red lead), yellow (orpiment), green (vergaut), black (carbon and iron gall ink), and white (gypsum). In addition, purple (orcein) is also discussed. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and characterization of thermally stable, high‐modulus polyimides containing benzimidazole moieties
Authors: Wang Shuang , Zhou Hongwei , Dang Guodong , Chen Chunhai 
Published: March 2009

AbstractA series of novel benzimidazole‐containing aromatic polyimides were prepared from synthesized 5,4′‐diamino‐2‐phenyl benzimidazole (DAPBI), and commercial dianhydrides by the conventional two‐step polymerization. The obtained films were amorphous and could afford flexible, transparent, and tough films with excellent thermal and mechanical properties. They showed high levels of tension strength of up to 234 MPa, modulus of up to 5.6 GPa without any stretching. According to thermal stability measurements, the glass‐transition temperatures of the polymers were observed between 329 and 425 °C. The 5% weight‐loss temperatures of most polyimides were above 600 °C in nitrogen. Excellent properties of these polyimides were proved to be attributed to the rigid‐rod structure and hydrogen bond of intermacromolecular. SAXS and SEM results showed self‐molecular orientation caused the formation of rod‐like extended conformations. It was demonstrated that high degree of supramolecular order led to the increase of thermal stability and mechanical properties of the polyimide films. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2024–2031, 2009
A novel computer‐assisted drill guide template for lumbar pedicle screw placement: a cadaveric and clinical study
Authors: Lu Sheng , Xu Yong Q. , Zhang Yuan Z. , Li Yan B. , Xie LE , Shi Ji H. , Guo Hai , Chen Guo P. , Chen Yu B 
Published: March 2009

AbstractBackgroundThe great accuracy of computer‐assisted operative systems for pedicle screw insertion makes them highly desirable for spinal surgeries. However, computer‐assisted pedicle screw placement is expensive, and the learning curve for these techniques is significant. We have developed a novel method of spinal pedicle stereotaxy by reverse engineering (RE) and rapid prototyping (RP) and have validated the method's accuracy by cadaveric and clinical study.MethodsA volumetric CT scan was performed on each desired lumbar vertebra and a three‐dimensional (3D) reconstruction model was generated with MIMICS 10.1, while the optimal screw size and orientation were determined using UG Imageware 12.1. A drill template was created using UG Imageware 12.1, with a surface that is the inverse of the vertebral surface. The drill template and its corresponding vertebra were manufactured using RP. The method was tested on six cadavers without any fluoroscopic control at surgery. Eventually, the technology was applied in six clinical cases.ResultsThe accuracy of the drill template was confirmed by preoperatively drilling the screw trajectory into the vertebra biomodel. In the cadaveric experiment, 36 pedicle screws were inserted and no pedicle perforation was observed by postoperative CT scan. In the six clinical patients, the best fit for positioning the template was easily found manually during the operation. The required time between fixation of the template to the lamina and insertion of the pedicle screw into each segment (one or two vertebrae) was 1–2 min. In total, 22 screws were inserted into T12‐L5, with two to four screws/patient. No misplacement occurred using the individual templates. Fluoroscopy was used only once after all the pedicle screws had been inserted. The method significantly reduces operation time and radiation exposure for the members of the surgical team.ConclusionsThe authors have developed a novel computer‐assisted drill template for lumbar pedicle screw placement. This method has shown its ability to customize the placement and size of each screw, based on the unique morphology of the lumbar vertebra. The potential use of drill templates to place lumbar pedicle screws is promising. Copyright © 2009 John Wiley & Sons, Ltd.