bluuebunny/crossref_metadata_2025_split huggingface dataset:
Substituent effects on the tautomer ratios between the hydra‐zone imine and diazenyl enamine forms in 3‐(arylhydra‐zono)methyl‐2‐oxo‐1,2‐dihydroquinoxalines. Correlation of the hammett constants σp with the tautomeric equilibrium constants KT
Authors: Kurasawa Yoshihisa , Hosaka Tomoyoshi , Takada Atsushi , Kim Ho Sik , Okamoto Yoshihisa 
Published: March 2009

AbstractThe 3‐(arylhydrazono)methyl‐2‐oxo‐1,2‐dihydroquinoxalines 1a‐e and 2a‐i showed tautomeric equilibria between the hydrazone imine A and diazenyl enamine B forms in dimethyl sulfoxide media. The sub‐stituent effects on the tautomer ratios of A to B in compounds 1a‐e and 2a‐i were studied by the nmr spec‐troscopy. The electron‐donating or electron‐withdrawing p‐substituents R1 in compounds 2a‐i represented a tendency to increase the ratios of the tautomer A or the tautomer B, respectively, exhibiting the linear correlation of the Hammett constants σp (‐0.17 to +0.78) with the tautomer ratios of A to B or the tautomeric equilibrium constants KT. However, the presence of the ester group R2 in compounds 1a‐e induced the exclusive existence of the tautomer A regardless of the nature of the p‐substituents R1. In the tautomeric thermodynamic study, the elevating temperature increased the ratios of the hydrazone imine tautomer A in compounds 2a‐i. The tautomeric thermodynamic parameters ΔG°, ΔH° and ΔS° were derived from the van't Hoff plots for compounds 2a,b,h,i, wherein the entropy term dominated the free‐energy difference between the A and B tautomers.
Preparation, structural characterization, and acid‐catalyzed isomerization of 3‐, 7‐, and 9‐benzyl‐6‐benzylthiopurines
Authors: Huang Jim J. , Ragouzeos Aris , Rideout Janet L. 
Published: March 2009

AbstractBenzylation of 6‐benzylthiopurine was examined. Structural assignments of the products were determined by 1‐D and 2‐D nmr spectroscopy (HMQC, HMBC, and nOe). In the presence of base, the isomeric N3‐, N7‐, and N9‐benzylated products 4, 3, and 2 were isolated; however, only 9‐benzyl‐6‐benzylthio‐purine (2) was obtained in the absence of base. In the latter case, the initially formed N3‐ and N7‐isomers were, in the presence of acid, converted to 9‐benzyl‐6‐benzylthiopurine (2) via a 6‐benzylthiopurine intermediate as evidenced by analysis of the reaction over time using reversed‐phase hplc.
AM1 semiempirical searching for suitable thiophene derivatives that will enable thiophenes to act as a diene in the diels‐alder reactions
Authors: Jursic Branko S. , Coupe Don 
Published: March 2009

AbstractThe AM1 semiempirical method was used for theoretical searching of activation of thiophene as a diene for the Diels‐Alder reaction. The reactivity of thiophene, electron‐withdrawing and electron‐donating substituted thiophenes, as well as the S‐methylthiophenium ion were studied as the diene for Diels‐Alder reactions by evaluating their frontier orbital energies and by calculating reaction barriers with activated and deactivated dienophiles. It was demonstrated that slight activation of the thiophene ring can be obtained with both electron‐donating and electron‐withdrawing groups attached to the thiophene ring. It was predicted that the actual transformation of thiophenes into the corresponding S‐methylthiophenium anions is the best means of activating the thiophenes. The calculated activation energies for normal (non‐activated) dienophiles are moderate so mild reaction conditions are predicted. If dienophiles are activated with electron‐donating substituents, AM1 calculations predict a two step cycloaddition reaction with a very small activation barrier.
Ring transformations of heterocyclic compounds. X. A simple method for the conversion of methyl substituted pyridinium salts into 2,4,6‐triarylphenyl derivatives: The first (thio)pyrylium ring transformations with heterocyclic anhydrobases as carbon nucleophiles
Authors: Zimmermann Thomas 
Published: March 2009

AbstractThe synthesis of 2,4,6‐triarylphenylpyridinium perchlorates 3 from methyl substituted derivatives 2 by a 2,6‐[C5+C] ring transformation of 2,4,6‐triaryl(thio)pyrylium salts 1/4 in the presence of triethylamine/acetic acid in ethanol is reported. Spectroscopic data of the pyridinium perchlorates 3 and their formation via anhydrobases of the salts 2 are discussed.
Synthesis of coumarin‐3‐O‐acylisoureas by dicyclohexylcarbodiimide
Authors: Bonsignore Leonardo , Cottiglia Filippo , Maccioni Anna M. , Secci Daniela , Lavagna Silvio M. 
Published: March 2009

AbstractThe synthesis and isolation of some O‐acylisoureas are described. The reaction between dicyclohexyl‐carbodiimide and coumarin‐3‐carboxylic acids leads to coumarin‐dicyclohexylisourea derivatives, isolated as the main products, and to coumarin‐dicyclohexylurea derivatives as byproducts.
Syntheses and photophysical properties of fluorescent dibenzofurans, a dibenzothiophene, and carbazoles substituted with benzoxazole and hydroxyl groups to produce excited state intramolecular proton‐transfer
Authors: Kauffman Joel M. , Litak Peter T. , Boyko Walter J. 
Published: March 2009

AbstractDibenzofurans, a dibenzothiophene, and carbazoles, each substituted with a 2‐benzoxazolyl group as well as an ortho‐hydroxyl group, were synthesized to produce fluors with fluorescence due to excited‐state intramolecular proton‐transfer. The orientations for Friedel‐Crafts acylation of 3‐methoxydibenzothio‐phene and of the analogous carbazole were determined. The fluors displayed absorption peaks in the 330–385 nm region with molar extinction coefficients up to 57,000. Fluorescence quantum efficiencies of 0.17–0.44 were obtained at wavelengths that had peak values from 540–600 nm. The fluors are of potential use as wavelength shifters in scintillating polystyrene fibers.
15N chemical shifts and long‐range 1H‐15N coupling pathways of selected strychnos alkaloids
Authors: Martin Gary E. , Crouch Ronald C. , Andrews C. Webster 
Published: March 2009

AbstractThe Strychnos alkaloids have been the focal point of considerable synthetic and spectroscopic effort. We now report the 15N chemical shifts and long‐range 1H‐15N coupling pathways of strychnine, brucine, and holstiine at natural abundance. Long‐range coupling pathways were established using a gradient‐enhanced HMQC sequence optimized for the observation of 1H‐15N long‐range couplings.
Long‐range 1H‐15N couplings and 15N chemical shift assignments of the bis‐indole anticancer drug navelbine®
Authors: Martin Gary E. , Crouch Ronald C. 
Published: March 2009

AbstractThe recently reported application of gradient‐enhanced HMQC for the observation of long‐range 1H‐15N heteronuclear couplings at natural abundance has been extended to the bis‐indole anticancer drug Navelbine®. Responses correlating protons to N16′ (δ 15N 138.2 ppm)in the velbanamine subunit and N1 and N9 (δ 15N 66.0 and 55.3 ppm, respectively) in the vindoline subunit were observable within about 4 hours of data acquisition. The single response to N6′ (δ I5N 43.0 ppm), in contrast, was very weak requiring a weekend data acquisition to even be observed. The difficulty in observing correlations to N6′ is presumably a function of molecular mobility in the eight‐membered azocine ring.
Synthesis of thieno[2′,3′(3′,4′ or 3′,2′):5,6]azepino[2,1‐a]isoindolediones from N‐Thienyl‐2(3)‐ylmethylphthalimides
Authors: Pigeon Pascal , Decroix Bernard 
Published: March 2009

AbstractReduction of N‐thienybnethylphthalimides 5a‐e followed by the Wittig reaction gave the substituted acetic acids 8a‐e. Their corresponding acyl chlorides where cyclized in the presence of aluminium trichloride to furnish the cyclic ketones 9a‐e. Treatment of these ketones with bromine followed by triethylamine, or with selenium dioxide led to the thienoazepinoisoindolediones 1a‐e.
Preparation and regiochemical assignments of new pyrazolo[3,4‐c] [2,1]benzodiazepines
Authors: Arranz Esther , Díaz Juan A. , Morante Esther , Pérez Carmen , Vega Salvador 
Published: March 2009

AbstractThe preparation of new pyrazolo[3,4‐c][2,1]benzothiazepines substituted at the nitrogen atoms of the pyrazole moiety is described. It was carried out by reaction of the 4,9‐dihydro‐9‐methyl‐4,10,10‐trioxo‐1(2)H‐pyrazolo[3,4‐c][2,1]benzothiazepine (1) with several alkylating agents under both classical and phase‐transfer catalysis (PTC) conditions. Assignments of theN‐alkyl regioisomers obtained were performed by study of their1H nmr spectra and NOE experiments.
Steroidal oxazoles, oxazolines, and oxazolidines
Authors: Camoutsis Charalambos 
Published: March 2009

AbstractIn recent years the interest of this investigator has been attracted to a series of new compounds in which a cyclopentanoperhydrophenanthrene system is condensed with various heterocyclic rings. As was to be expected, the addition of heterocycles to steroids often leads to a change of their physiological activity and the appearance of new interesting biological properties. Since the numerous data on the synthesis and properties of the steroidal oxazoles, oxazolines, and oxazolidines are scattered, this stimulated us to write the present review, in which the literature published up to the end of 1994 is systematized.
Synthesis of substituted furo[3,2‐e][1,2,4]triazolo[4,3‐c]pyrimidines and furo[3,2‐e]tetrazolo[1,5‐c]pyrimidines
Authors: Lockhart Christopher C. , Sowell J. Walter 
Published: March 2009

AbstractA series of substituted furo[3,2‐e][1,2,4]triazolo[4,3‐c]pyrimidines and furo[3,2‐e]tetrazolo[1,5‐c]pyrimidines were obtained from reactions of substituted 2‐dimemylamino‐4‐hydrazmofuro[2,3‐d]pyrimidines with orthoesters or sodium nitrite in acetic acid, respectively.
Ring closure reactions of cyclic 2‐arylaminomethylene‐1,3‐diones
Authors: Van Tinh Dang , Fischer Michaela , Stadlbauer Wolfgang 
Published: March 2009

Abstract5‐Arylaminomethylene compounds such as 5‐arylaminomethylenepyrimidine‐2,4,6‐triones 2 or 2‐phenylaminomethylenephenalene‐1,3‐dione 13 cyclize by thermolysis via migration of the arylamino group to pyrimido[4,5‐b]quinoline‐2,4‐diones 6 or 7‐oxo‐7H‐naphtho[1,8‐bc]acridine 15, respectively. 2‐Phenylaminomethylenecyclohexane‐1,3‐dione 8 cyclizes to 9,9‐dimethyl‐9,10‐dihydrophenanthridin‐7(8H)‐one 11 without rearrangement.
The synthesis of novel polycyclic heterocyclic ring system via photocyclization. 18. Benzo[h]naphtho‐[1′,2′:4,5]thieno[2,3‐c]quinoline and benzo[h]naphtho‐[1′,2′:4,5]thieno[2,3‐c] [1,2,4]triazolo[4,3‐a]quinoline
Authors: Luo Jiann‐Kuan , Federspiel Ronald F. , Castle Raymond N. 
Published: March 2009

AbstractThe synthesis of two previously unknown polycyclic ring systems, benzo[h]naphtho[1′2′:4,5]‐thieno[2,3‐c]quinoline (1) and benzo[h]naphtho[1′,2′:4,5]thieno[2,3‐c][1,2,4]triazolo[4,3‐a]quinoline (2), was achieved via oxidative photocyclization of 1‐chloro‐N‐(1‐naphthyl)naphtho[2,1‐b]thiophene‐2‐carboxamide (5). The total assignment of their 1H and 13C nmr spectra was determined by the concerted use of two‐dimensional nmr methods.
Ring closure reactions of azidouracils to oxazolo‐ and isoxazolopyrimidines
Authors: Van Tinh Dang , Stadlbauer Wolfgang 
Published: March 2009

AbstractThermolysis of 6‐azidouracils 1 in the presence of polyphosphoric acid leads either to oxazolo[5,4‐d]pyrimidine‐5,7‐diones 5 (by reaction with benzoic acid 2a) or to isoxazolo[3,4‐d]pyrimidine‐4,6‐diones 7 (by reaction with aliphatic carboxylic acids 2b,c). 5‐Benzoylpyrimidinetriones 12 could be shown to cyclize to isoxazolo[5,4‐d]pyrimidine‐4,6‐diones 15 by chlorination with phosphorus pentachloride and subsequent reaction with sodium azide.
The estimation of the aromaticity of five‐membered and benzo fused five‐membered rings by the hybrid DFT computed magnetic properties
Authors: Jursic Branko S. 
Published: March 2009

AbstractThe structures of thiophene, pyrrole, furan, and their benzo derivatives were generated with the hybrid B3LYP density functional theory (DFT) methods employing a 6‐31G* basis set. Their magnetic susceptibility anisotropics were calculated on these geometries with a continuous set of gauge transformations. The aromaticity of the heterocycles was discussed in light of their structural uniformity and magnetic susceptibility. The computed structural parameters, order of aromaticity, stability, and reactivity is in excellent agreement with the experimental results. The usefulness of this approach to determine the reactivity is discussed.
The synthesis and reactions of 4‐(2‐ and 3‐thienyl)‐tetrahydroisoquinolines
Authors: Tupper David E. , Hotten Terrence M. , Prowse William G. 
Published: March 2009

AbstractTetrahydroisoquinoline derivatives substituted in the 4‐position by either a 2‐ or 3‐substituted thiophene ring have been synthesised. Simple electrophilic substitution reactions of these systems take place as expected in the α‐position of the thiophene ring. Metalation reactions are more complex and take place at the benzylic 4‐position of the tetrahydroisoquinoline nucleus in the case of the 2‐substituted thiophene derivatives or at either the thiophene α‐positions or the benzylic 4‐position depending on the nature of the attacking electrophile in the case of the 3‐substituted thiophene system.
Synthesis of 2‐imino‐4‐thiazolines, 2‐imino‐4‐alkoxythiazolidines, thiazoles and 4‐imidazolin‐2‐ones from α‐halomethyl ketimines
Authors: De Kimpe Norbert , De Cock Wim , Keppens Marian , De Smaele Dirk , Mészáros Andrea 
Published: March 2009

AbstractA variety of heterocycles, including 3,4‐disubstituted‐2‐imino‐4‐thiazolines, 3,4‐disubstituted‐4‐methoxy‐2‐iminothiazolidines, 2,4‐disubstituted‐thiazoles, 2‐amino‐4‐substituted‐thiazoles and 1,5‐disubstituted‐4‐imidazolin‐2‐ones, were synthesized from α‐chloromethyl and α‐bromomethyl ketimines by condensation with potassium thiocyanate, thiourea, ammonium thiocyanate and potassium cyanate.
The reaction of phenylglyoxal with 2‐aminoalcohols. Rearrangement of 2‐acyloxazolidines to 2‐hydroxy‐5,6‐dihydro‐1,4‐oxazines
Authors: Sheradsky Tuvia , Silcoff Elliad R. 
Published: March 2009

AbstractThe reactions of phenylglyoxal hydrate with (R)‐phenylglycinol and with (1S,2R)‐norephedrine were investigated. The expected 2‐benzoyloxazolidines 3 and 2a, respectively are initially formed, and undergo a fast, spontaneous stereospecific rearrangement to the corresponding 2‐hydroxy‐3‐phenyl‐5,6‐dihydro‐1,4‐oxazines 4 and 5 respectively. The mechanism of this new rearrangement is discussed. The structures and stereochemistry of 4 and 5 were established by X‐ray diffraction analysis.
Concurrent alkylation‐methoxylation of 4,5‐dihalopyridazin‐6‐ones and synthesis of 5‐halo‐4‐hydroxypyridazin‐6‐ones
Authors: Cho Su‐Dong , Choi Woo‐Yong , Yoon Yong‐Jin 
Published: March 2009

Abstract1‐Alkyl‐5‐halo‐4‐methoxypyridazin‐6‐ones were synthesized from 1‐alkyl‐4,5‐dihalopyridazin‐6‐ones by the concurrent alkylation‐methoxylation. 1‐Alkyl‐5‐halo‐4‐hydroxypyridazin‐6‐ones were also prepared.
Functionalization of near‐infrared cyanine dyes
Authors: Strekowski Lucjan , Lipowska Malgorzata , Górecki Tadeusz , Mason J. Christian , Patonay Gabor 
Published: March 2009

AbstractAn indolium heptamethine cyanine dye 11 containing an isothiocyanate function for selective coupling of the dye chromophore with a primary amino group of proteins has been synthesized. Functionalization of a benzothiazolium heptamethine cyanine 12 is discussed.
Cyclization of 2‐ and 3‐indolythioalkanoic acids to novel indole‐containing tricyclic ring systems
Authors: Hamel Pierre , Girard Mario 
Published: March 2009

AbstractA series of 2‐ and 3‐indolylthioalkanoic acids of various chain lengths were cyclized under dehydrative conditions affording tricyclic indole‐containing ring systems wherein the third ring contains a sulfur atom attached to the 2‐ or 3‐position of the indole ring. This methodology affords entry into the novel thiepino[3,2‐b]indole, thiocino[2,3‐b]indole and thiocino[3,2‐b]indole ring systems.
Application of the hurd‐mori‐reaction for the synthesis of tricyclic annelated 1,2,3‐thiadiazoles
Authors: Stanetty Peter , Kremslehner Manfred , Müllner Martin 
Published: March 2009

AbstractThe synthesis of methyl naphtho[1,2‐d][1,2,3]thiadiazole‐4‐carboxylate 1a as well as the corresponding thienobenzo[1,2,3]thiadiazoles 1b and 1c is reported using the Hurd‐Mori reaction in the key step. Treatment of the readily available tosylhydrazones 10a‐c with thionyl chloride surprisingly affords the fully aromatic products 1a‐c, instead of the expected annelated 4,5‐dihydro[1,2,3]thiadiazoles 2a‐c. Based on these results a mechanism for the aromatization step with thionyl chloride is proposed.
A convenient synthesis of 4‐amino‐3,5‐dialkyl‐4H‐1,2,4‐triazoles
Authors: Lkizler Aysun , Demirbas Neslihan , Lkizler Aykut A. 
Published: March 2009

AbstractEster tert‐butoxycarbonylhydrazones 2 were reacted with some carboxylic acid hydrazides to give 4‐terrtutoxycarbonylamino‐3,5‐dialkyl‐4H‐1,2,4‐triazoles 3–6. Treatment of 3–5 with 6 N hydrochloric acid under mild conditions resulted in the formation of 4‐ammo‐3,5‐dialkyl‐4H‐1,2,4‐triazole hydrochlorides 7–9 in good yields. Compound 7a was converted to the free 4‐amino compound 10a upon treatment with ethanolic sodium ethoxide solution.
Substitution reactions of phenanthro[9,10‐d]triazole with benzyl chlorides
Authors: Yasuda Goro , Kimoto Hiroshi 
Published: March 2009

AbstractThe reaction of the potassium salt of phenanthro[9,10‐d]triazole and benzyl chloride gave 2‐(benzyl)‐2H‐phenanthro[9,10‐d]triazole (2a) in 15% yield. The other regio‐isomer, 1‐(benzyl)‐1H‐phenanthro[9,10‐d]‐triazole (1a), was obtained as a by‐product in 3.9% yield. Similar reactions with benzyl chlorides having a methyl, a chloro or a nitro group on the aromatic ring gave the corresponding two products, 1b‐j and 2b‐j. In all cases, 2b‐j were major products in yields of 14–62%, 1b‐j were minor ones in yields of 1.4–7.6%. The structures of the isomers were confirmed by X‐ray crystal analyses.
Cyclization reactions of 2‐(2‐chloro‐4‐nitrophenylsulfonyl)‐1‐(2‐thienyl)ethanone
Authors: Fan Ai‐Long , Cao Song , Xu Jing‐Hua , Zhang Zheng 
Published: March 2009

AbstractA new sulfonyl group‐containing heterocyclic compound 2‐(2‐chloro‐4‐nitrophenylsulfonyl)‐1‐(2‐thienyl)ethanone2was prepared from the corresponding sulfide 2‐(2‐chloro‐4‐nitrophenylthio)‐1‐(2‐thienyl)ethanone1. Two different cyclization reactions of the compound2were discussed. In contrast to the tandem alkylation‐cyclization process [1], another cyclic procedure was described. In the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene as a base and dimethylformamide as a solvent, compound2was treated with ethyl acrylate or methyl methacrylate at 50–55° to give the 1,4‐benzoxathiin 4,4‐dioxide5or6respectivelyviaa tandem Michael conjugate addition‐cyclization process.
Conjugate addition of grignard reagents to N‐(α,β‐unsaturated)acylpyrazoles. Diastereoselective β‐alkylation using 3‐phenyl‐l‐menthopyrazole
Authors: Kashima Choji , Takahashi Katsumi , Fukusaka Kiyoshi , Hosomi Akira 
Published: March 2009

AbstractThe conjugate additions of N‐(α,β‐unsaturated)acylpyrazoles were carried out by the treatment with Grignard reagents in the presence of cuprous halides. The reaction of 2‐(α,β‐unsaturated)acyl‐3‐phenyl‐l‐menthopyrazoles 3a‐h occurred in higher chemical yields and with asymmetric inductions on β‐position, where the addition of magnesium bromide as a Lewis acid influenced to the yields and the diastereoselectivities. In the case of α‐methylated 2‐(α,β‐unsaturated)acyl‐3‐phenyl‐l‐menthopyrazoles 3i‐n, the excellent asymmetric induction on the α‐position was also observed through the diastereofacial protonation.
Synthesis of 4‐ and 5‐(s‐triazolo[4,3‐b]pyridazinyl‐3)‐substituted cyclic polyols
Authors: Turk Cvetka , Svete Jury , Golobič Amalija , Golič Ljubo , Stanovnik Branko 
Published: March 2009

Abstract4(R)‐(6‐Chloro‐s‐triazolo[4,3‐b]pyridazinyl‐3)‐1,4‐furanoses 10 and 11, 5(R)‐(6‐chloro‐s‐triazolo[4,3‐b]pyridazinyl‐3)‐1,5‐pyranose 13, and 2(S),3(R)‐dihydro‐5‐(6‐chloro‐s‐triazolo[4,3‐b]pyridazinyl‐3)‐2,3‐O‐isopropylidenefuran (12) were prepared by cyclization of hydrazones 6–9 obtained from 6‐chloro‐3‐hydrazinopyridazine (1) and aldofuranoses 2, 3 and 4, and aldopyranose 5.
Synthesis of methyl derivatives of linear and angular thienocoumarins and thiopyranocoumarins
Authors: Rodighiero P. , Pastorini G. , Chilin A. , Marotto A. 
Published: March 2009

AbstractNew linear and angular thienocoumarins and thiopyranocoumarins were synthesized. The key intermediates were appropriate methyl derivatives of 7‐mercaptocoumarin, which were condensed with chloro‐ketones or propargyl chloride. Thioethers were cyclized under various conditions in order to determine which methods produced the best yields of the desired thienocoumarins 15, 16, 17, 18, 22, 23, 24, 27 and thiopyranocoumarins 28 and 29.
Heterocyclic and acyclic azadiene diels‐alder reactions: Total synthesis of nothapodytine B
Authors: Boger Dale L. 
Published: March 2009

AbstractA summary of the applications of the inverse electron demand Diels‐Alder reactions of heterocyclic and acyclic azadienes in the total synthesis of natural products is provided and a recent application in the total synthesis of nothapodytine B (mappicine ketone) is presented in detail.
Retro‐Ene reaction. VI. Functionalization of 4,5‐dihalopyridazin‐6‐ones using 1‐acetyloxymethyl‐4,5‐dihalopyridazin‐6‐ones as the 1‐O, 3‐N, 5‐O ene‐adduct
Authors: Chung Hyun‐A , Kang Young‐Jin , Kweon Deok‐Heon , Yoon Yong‐Jin 
Published: March 2009

AbstractFunctionalization of 1‐acetyloxymethyl‐4,5‐dihalopyridazin‐6‐ones via retro‐ene reaction with some nucleophiles gave regioselectively only 5‐halo‐4‐substitutedpyridazin‐6‐ones.
Synthesis and reactions of 4‐Hydroxy‐2(1H)‐pyridones with thienyl and pyridyl substituents in position 6 starting with azomethines and malonates
Authors: Schnell Barbara 
Published: March 2009

AbstractThe reaction of 4 with substituted diethyl malonates 5a, or “magic malonates” (bis‐2,4,6‐trichlorophenylmalonates 5b) leads to 4‐hydroxy‐2(1H)‐pyridones 6. The azomethines 4 are prepared via the Strecker compounds 3 starting with methyl ketones 1, anilines, and potassium cyanide. Chlorination of pyridones 6 with sulfuryl chloride leads to compounds 7 while nitration gives 9.
An improved synthetic approach to thieno[2,3‐d]‐1,2,3‐thiadiazolecarboxylates via diazotization of aminothiophene derivatives
Authors: Stanetty Peter , Görner Erwin , Mihovilovic Marko D. 
Published: March 2009

AbstractThe common synthetic method for the synthesis of fused 1,2,3‐thiadiazoles via diazotization is not generally applicable to aminothiophenes. A substantially improved experimental protocol for the preparation of the title compounds as a potential inducer of systemic acquired resistance in plants is reported based on a novel cyclization mechanism via a Huisgen‐White type rearrangement.
Ring transformations of heterocyclic compounds. XVII, 2‐(2,4,6‐Triarylphenyl) substituted dihydro‐1H‐imidazolium, dihydrothiazolium and thiazolium salts from 2‐methyl derivatives by pyrylium and thiopyrylium ring transformations
Authors: Zimmermann Thomas 
Published: March 2009

AbstractThe synthesis of hitherto unknown 2‐(2,4,6‐triarylphenyl) substituted 4,5‐dihydro‐1H‐imidazolium perchlorates 6, 4,5‐dihydrothiazolium perchlorates 8 and thiazolium perchlorates 9 from their 2‐methyl derivatives 2, 4 and 5, respectively, by a 2,6‐[C5+C] ring transformation of 2,4,6‐triarylpyrylium and ‐thiopyrylium salts 1/10 in ethanol in the presence of an appropriate base (6: sodium ethanolate; 8,9: anhydrous sodium acetate) is reported. Spectroscopic data of the transformation products and structural influences on their formation via anhydrobases of the salts 2, 4 and 5 are discussed.