bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and spectroscopic properties for six 7,16‐dibenzoylated tetraaza[14]annulene nickel(II) complexes
Authors: Sakata Kazunori , Koyanagi Ken , Hashimoto Mamoru 
Published: March 2009

AbstractThe condensation reaction between tetraaza[14]annulene nickel(II) complex and a series of para‐substituted benzoyl chlorides gave the corresponding 7,16‐dibenzoylated products in 53–98% yields. The mass spectra exhibit molecular ion peaks ascribed to the 7,16‐dibenzoylated products. The intense ir band due to the CO stretching mode in these nickel(II) complexes is present in the 1650–1658 cm−1 range upon the benzoylation. Even though the ligand moiety of these six complexes is changed by benzoylation, the electronic spectra hardly vary. These nickel(II) complexes assume roughly the square‐planar coordinations as judged by the ligand‐field transition bands. The olefinic proton peaks at the 7‐ and 16‐positions vanish on benzoylation in the proton nmr spectra and the proton signals of the para‐substituted benzoyl groups are observed in the 2.4–8.4 ppm region. The results of the carbon‐13 nmr spectra are compatible with those for the proton nmr spectra.
Pyridine‐substituted hydroxythiophenes. IV. Preparation of 3‐ and 4‐(2‐, 3‐ and 4‐pyridyl)‐2‐hydroxythiophenes
Authors: Zhang Yihua , Hörnfeldt Anna‐Britta , Gronowitz Salo 
Published: March 2009

Abstract3‐(2‐, 3‐ and 4‐Pyridyl)‐2‐methoxythiophenes have been prepared in good yields through the Pd(0)‐cat‐alyzed coupling of the three isomeric bromopyridines with 3‐trimethylstannyl‐2‐methoxythiophene. This compound was prepared through halogen‐metal exchange of 3‐bromo‐2‐methoxythiophene followed by stannylation. 3‐Bromo‐2‐methoxythiophene was prepared by dibromination and α‐debromination of 2‐methoxythiophen. Most attempts to demethylate 2‐methoxy‐3‐pyridylthiophenes using a large variety of reagents failed, probably due to the instability and high reactivity of the desired 3‐pyridyl‐2‐hydroxythiophene systems. Only 2‐methoxy‐3‐(3‐pyridyl)thiophene reacted with boron tribromide to give 3‐(3‐pyridyl)‐3‐thiolene‐2‐one, which only was stable in ether solution at −20°. The attempted demethylation of 2‐methoxy‐3‐(2‐pyridyl)thiophene with trimethylsilane chloride/sodium iodide in refluxing acetonitrile led to a dimer. Demethylation of the 2‐methoxy‐3‐pyridylthiophenes with dibenzyl diselenide and sodium borohydride gave 3‐pyridylthiophan‐2‐ones.A number of other routes to prepare 3‐pyridyl‐2‐hydroxythiophenes were also explored, but none of them gave the desired compounds. On the other hand, the 4‐(2‐, 3‐, and 4‐pyridyl)‐2‐hydroxythiophene systems could easily be prepared by hydrogen peroxide oxidation of the corresponding 4‐pyridyl‐2‐thiopheneboronic esters, which were obtained from 2‐bromo‐4‐pyridylthiophenes by halogen‐metal exchange followed by reaction with ethyl borate. The 2‐bromo‐4‐pyridylthiophenes were prepared by dibromination of the known 3‐pyridylthiophenes to the 2,5‐dibromo derivatives, and removal of the 2‐bromine by halogen‐metal exchange at −100°, followed by hydrolysis. The 1H nmr and ir spectroscopic investigations show that these quite stable 2‐hydroxythiophene systems exist exclusively in the 4‐pyridyl‐3‐thiolen‐2‐one forms.
Synthesis and properties of two new N‐alkyl substituted phthalocyanines
Authors: Fernández Daniel A. , Dicelio Lelia E. , Awruch Josefina 
Published: March 2009

AbstractThe synthesis and properties of tetrakis(1,1‐dimethyl‐2‐phthalimido)ethylphthalocyaninato zinc(II) (6) and tetrakis(1,1‐dimethyl‐2‐amino)ethylphthalocyaninato zinc(II) (7) are described. N‐Alkyl substituted phthalonitrile 5 was converted to phthalocyanine 6. which was deprotected to afford the free amino phthalocyanine 7.
Synthesis and reactions of dinitrated amino and diaminopyridines
Authors: Ritter H. , Licht H. H. 
Published: March 2009

AbstractNitration of amino‐ and diaminopyridines and ‐picolines led, in unexpected one‐step reactions, to dinitrated derivatives. Dinitropicolines gave styrylpyridines, and 2‐amino‐6‐hydroxy‐3,5‐dinitropyridine was transformed by the thermolysis of its azido derivative into 5‐amino‐6‐nitro[1,2,5]oxadiazolo[3,4‐b]pyridine. Using 1H and 13C nmr spectroscopy, azido‐tetrazole tautomerism of 2‐amino‐6‐azido‐3,5‐dinitropyridine and intramolecular hydrogen bonding at 20° for several 2‐amino‐3,5‐dinitro‐6‐R‐pyridines have been proved.
Enolethers. XXI. Synthesis of 5,5′‐disubstituted 4,4′‐bipyrimidines
Authors: Effenberger Franz , Barthelmess Ingrid 
Published: March 2009

Abstract1,6‐Dialkoxy‐3,4‐diones 3 are easily accessible by acylation of enol ethers 1 with oxalyl chloride and subsequent elimination of hydrogen chloride using triethylamine. The open‐chain 2,5‐dimethyl derivative 3b is converted with amidines 4a‐c and S‐methylisothiourea (4d), respectively, to give 2,2′‐disubstituted 5,5′‐dimethyl‐4,4′‐bipyrimidines 5a‐d. The dihydrofuran and dihydropyran derivatives 3c and 3d, however, react with benzamidine (4c) in dimethylformamide only in the presence of calcium hydride as condensation agent yielding 5,5′‐bis(2‐hydroxyethyl)‐ and 5,5′‐bis(3‐hydroxypropyl)‐2,2′‐diphenyl‐4,4′‐bipyrimidine 6a and b.
Synthesis of 9H‐pyrrolo[2,1‐b][1,3,6]benzothiadiazocin‐10(11H)‐one 4,4‐dioxide, a potential anti‐HIV‐1 agent
Authors: Silvestri Romano , Pagnozzi Eugenia , Artico Marino , Stefancich Giorgio , Massa Silvio , La Colla Paolo 
Published: March 2009

AbstractStarting from 2‐(2‐aminophenylthio)‐1‐ethoxycarbonylmethyl‐1H‐pyrrole a four‐step synthesis of 9H‐pyrrolo[2,1‐b][1,3,6]benzothiadiazocin‐10(11H)‐one 4,4‐dioxide, a new heterocycle related to anti‐HIV‐1 tricyclic non‐nucleoside agents, is described.
An effective synthesis of fused cyclic thiopyrans and pyrans by molybdenum(VI) sulfide catalyzed reduction of the corresponding thiopyranones and pyranones
Authors: Takido Toshio , Itabashi Kunio , Takagi Yuzuru 
Published: March 2009

AbstractThe synthesis of fused cyclic dihydrothiopyrans 2a‐c from dihydrothiopyranones 1a‐c and thiopyrans 2d‐f from thiopyranones 1d‐f by catalytic reduction over molybdenum(VI) sulfide (MoS3) has been studied. The hydrogenolysis of the carbonyl group of 1a‐f over MoS3 catalyst proceeded selectively to give the corresponding 2a‐f in high yields. Neither alcohols nor olefins were not detected in the products. The method was also applied successfully to the synthesis of dihydropyran 2h and pyran 2g from dihydro‐pyranone 1h and pyranone 1g.
Unambiguously confirmed structure of 2‐phenacylidene‐1,2‐dihydro‐4H‐pyrido[2,3‐b]pyrazin‐3‐one and 3‐phenacylidene‐3,4‐dihydro‐1H‐pyrido[2,3‐b]pyrazin‐2‐one
Authors: Seki Taketsugu , Sakata Hisanori , Iwanami Yasuo 
Published: March 2009

AbstractTo determine the structures of two isomeric products, 2‐phenacylidene‐1,2‐dihydro‐4H‐pyrido[2,3‐b]pyrazin‐3‐one (2) and 3‐phenacylidene‐3,4‐dihydro‐1H‐pyrido[2,3‐b]pyrazin‐2‐one (3) obtained by condensation of 2,3‐diaminopyridine (1) with ethyl benzoylpyruvate [1–3], these compounds were hydrolyzed to give 2‐methyl‐4H‐pyrido[2,3‐b]pyrazin‐3‐one (4) and 3‐methyl‐1H‐pyrido[2,3‐b]pyrazin‐2‐one (5), respectively [4,5]. Both hydrolysates 4 and 5 were hydrogenated to afford 2‐methyl‐1,2‐dihydro‐4H‐pyrido[2,3‐b]pyrazin‐3‐one (6) and 3‐methyl‐3,4‐dihydro‐1H‐pyrido[2,3‐b]pyrazin‐2‐one (7). The latter compound was identical with an unequivocally synthesized compound providing proof for the structures of all these compounds.
First synthesis of (±)‐harzianopyridone by metalation of polysubstituted O‐pyridylcarbamates
Authors: Tréecourt Françcois , Mallet Marc , Mongin Olivier , Quéguiner Guy 
Published: March 2009

AbstractThe first synthesis of (±)‐harzianopyridone, an antifungal metabolite of Trichoderma harzianum, has been achieved by metalation of 6‐substituted‐2,3‐dimethoxy‐4‐pyridyl‐N,N‐diisopropylcarbamates. Moreover, the chosen strategy allowed the preparation of harzianopyridone analogs, by varying the groups at C‐4, C‐5 and C‐6 on the pyridine ring.
Acetylenic amides. 3. The synthesis of 5‐methylene‐2,4‐imidazolidinediones from 2‐propynamides and isocyanates
Authors: Coppola Gary M. , Damon Robert E. 
Published: March 2009

Abstract2‐Propynamides react with aryl isocyanates in the presence of triethylamine to give 5‐methylene‐2,4‐imidazolidinediones 5 in good yields. If the propynamide contains a terminal trimethylsilyl group, Z‐trimethylsilylidenehydantoin (7) is produced.
Synthesis of 6,7,8,9‐tetrahydro‐N,N‐di‐n‐propyl‐1H‐benz[g] indol‐7‐amine, a potential dopamine receptor agonist
Authors: Demopoulos Vassilis J. , Gavalas Antonis , Rekatas George , Tani Ekaterini 
Published: March 2009

AbstractIn this work, the synthesis of 6,7,8,9‐tetrahydro‐N,N‐di ‐n‐propyl‐1H‐benz[g]indol‐7‐amine (1) is described. This compound was designed as an indole bioisostere to the known dopamine receptor agonist 5‐OH‐aminotetraline 2. The key step of the synthesis was a Mukaiyama type aldol condensation between the dimethyl acetal of 1‐(p‐toluenesulfonyl)pyrrole‐3‐acetaldehyde (4) and 4‐di‐n‐propylamino‐1‐trimethylsilyloxycyclohexene (8) followed by cycloaromatization to afford 1‐p‐toluenesulfonyl‐6,7,8,9‐tetrahydro‐N,N‐di‐n‐ propyl‐1H‐benz[g]indol‐7‐amine (10). Scission of the sulfonamide bond in 10 gave the target compound 1. A byproduct which was isolated was assigned to the structure of 1‐(p‐toluenesul‐fonyl)‐6‐[3‐[1‐(p‐toluenesulfonyl)]pyrrolyl]indole (11). This compound was also synthesized in good yield by an acid catalyzed dimerization of the dimethyl acetal of 1‐(p‐toluenesulfonyl)pyrrole‐3‐acetaldehyde (4). Preliminary screening of 1 indicated that it possesses central dopamine receptor agonist properties.
Synthesis and properties of 5‐(p‐carbomethoxyphenyl)‐ 15‐(p‐dimethylaminophenyl)porphyrin
Authors: Zindel Jürgen , Lightner David A. 
Published: March 2009

AbstractAn unsymmetrically substituted 5,15‐diarylporphyrin 1, with p‐dimethylamino and p‐carbomethoxy substituents, was synthesized via a MacDonald condensation of aryldipyrromethane precursors 6 and 12, which were prepared in good yield by three or four step procedures starting from ethyl 3,4‐dimethyl‐1H‐pyrrole‐2‐carboxylate (2).
Reactions of thioquinanthrene with alkanethiolates. The smiles rearrangement of diquinolinyl sulfides
Authors: Pluta Krystian 
Published: March 2009

AbstractReactions of thioquinanthrene 1 with alkali metal alkanethiolates in DMSO or DMF at 70° proceeded through a stage of the S→S type of the Smiles rearrangement (3′‐quinolinethiolate 2A→4′‐quinolinethiolate 3A) to give 4,4′‐dialkylthio‐3,3′‐diquinolinyl sulfides 3 as the final products. When these reactions were carried out at 20° two types of the products were isolated: 3′,4‐dialkylthio‐3,4′‐diquinolinyl sulfides 2 or sulfides 3 depending on the reaction time (1 hour or 7 days). Under acidic conditions 3′‐quinolinethiolate 2A underwent intramolecular cyclization to dithiin 1. Reactions of dithiin 1 with sodium alkanethiolates at 20°, realized as a one‐pot procedure, led to various 3,4‐dialkylthioquinolines 7. The rearrangement of other 3′‐quinolinethiolates 8A and 11A (the products of the reactions of dithiin 1 with sodium sulfide and sodium methoxide) needed higher temperature (140°).
Triazoles XXXVI. The arylation of 5‐amino‐3‐methylthio‐1H‐1,2,4‐triazole with activated aryl chlorides
Authors: Trinka Péter , Reiter József 
Published: March 2009

AbstractThe possibility of the arylation of 5‐amino‐3‐methylthio‐1H‐1,2,4‐triazole (1) with different chlorobenzenes activated by a nitro group was studied. The ratio of products obtained was determined by hplc using isolated products as standards. It was stated that from among the monoarylated products 8, 9 and 10 obtained the main product is 8. However, from the reaction mixtures diarylated derivatives 11 and 12 and different by products such as 15, 16, 22, 24, 25, 27, 28, 32, 36, and 38 were also isolated.
Studies on pyrrolidinones. Synthesis of some N‐fatty acylpyroglutamic acids
Authors: Rigo BenoÎT , Kolokouris Antonios , Kolokouris Nicolas 
Published: March 2009

AbstractStarting from readily available pyroglutamic acid 1, some N‐fatty acylpyroglutamic acids were synthesized and characterized by their spectral data. A preliminary pharmacological study showed that N‐stearoylpyroglutamic acid 4c displays a CNS stimulating effect on mice.
The reaction of imidazo[1,5‐a]pyridines with methyl‐ and phenyltriazolinediones and with diethyl azodicarboxylate
Authors: Anderson David J. , Watt William 
Published: March 2009

AbstractImidazo[1,5‐a]pyridines react in one of two ways with methyl‐ and phenyl triazolinediones and diethyl azodicarboxylate to give either Michael type addition products at C‐3 or C‐1, or novel 1,2,4‐triazolines. The nature of the product depends upon the dienophile and the substitution pattern of the imidazo[1,5‐a]pyridine.
Selective synthesis of monoaryl substituted porphyrins
Authors: Robinsohn Adriana E. , Buldain Graciela Y. 
Published: March 2009

AbstractA synthetic route to meso‐monoarylporphyrins using a MacDonald‐type 2 + 2 condensation is described. In this method a bisformyl substituted dipyrrylmethane is treated with a biscarboxydipyrrylmethane. The 5‐aryldipyrrylmethanes 15, 25 and 27 were obtained by condensation of the corresponding pyrroles 18, 28 and 29 respectively with benzaldehyde in presence of p‐toluenesulfonic acid.
Studies on pyrrolidinones. Synthesis and reactivity of somen‐protected pyroglutamic derivatives
Authors: Rigo BenoÎT , Erb BÉNÉDicte , El Ghammarti Samira , Gautret Philippe , Couturier Daniel 
Published: March 2009

AbstractThe synthesis of pyroglutamoyl chlorideN‐protected by a methoxycarbonyl or a trifluoroacetyl group is described. Some aspects of the reactivity of these compounds and intermediates have been studied.
Isolation and elucidation of the structure of homocryptolepinone
Authors: Sharaf Maged H. M. , Schiff Paul L. , Tackie Albert N. , Phoebe Charles H. , Davis Ann O. , Webster Andrews C. , Crouch Ronald C. , Martin Gary E. 
Published: March 2009

AbstractThe structure of a new indolobenzazepine alkaloid, homocryptolepinone, isolated from extracts of the roots of the indigenous Ghanaian medicinal plant Cryptolepis sanguinolenta, is reported. The structure was determined using mass spectrometric, one‐dimensional nOe difference nmr, and inverse‐detected two‐dimensional nmr experiments which included HMQC, IDR‐(Inverted Direct Response)‐HMQC‐TOCSY, and HMBC experiments. The structure of homocryptolepinone is significant in that it may provide insight into the biogenesis of the benzpyrrolizinobenzazepine portion of the structure of the complex spiro nona‐cyclic alkaloid cryptospirolepine previously isolated in these laboratories from C. sanguinolenta, and which has no precedent in alkaloid chemistry.
Thieno[2,3‐b]indole. The unsubstituted ring system
Authors: Olesen Preben H. , Hansen John B. , Engelstoft Mogens 
Published: March 2009

AbstractMethyl thieno[2,3‐b]indolecarboxylate (2) was prepared from methyl 1‐benzylthieno[2,3‐b]indole‐carboxylate by debenzylation with aluminium trichloride in toluene. Compound2was in one step saponified and decarboxylated by heating in morpholine to give the previously unreported parent heterocycle thieno[2,3‐b]indole.
NOE difference spectroscopy of some 5‐substituted and 5,5‐disubstituted hydantoins
Authors: De Rosa Michael , Freyer Alan J. 
Published: March 2009

AbstractThe nOe difference (NOED) spectra of twelve 5‐substituted‐ and 5,5‐disubstituted hydantoins were recorded in deuteriochloroform. The nOe's observed from the interaction of substituents on C‐5 with the proton on N‐1 are more reliable than the chemical shift of the N‐1 proton for structure determination.
Synthesis of new 1,2,3‐triazolo[1,2‐a]benzotriazoles or 2,3‐benzo‐1,3a,6,6a‐tetraazapentalenes
Authors: Biagi Giuliana , Giorgi Irene , Livi Oreste , Scartoni Valerio , Barili Pier Luigi 
Published: March 2009

AbstractSome new v‐triazolo[1,2‐a]benzotriazoles or 2,3‐benzo‐1,3a,6,6a‐tetraazapentalenes were prepared according to previously employed synthetic routes concerning deoxycyclization reactions of appropriate nitrophenyl‐1,2,3‐triazole derivatives and/or thermal decompositions of appropriate azidophenyl‐1,2,3‐triazoles. The nitration of 9‐phenyl‐1,2,3‐triazolo[1,2‐a]benzotriazoles allowed the isolation of some mononitro‐ and trinitro‐derivatives, whose structures were assigned by chemical and spectroscopic methods.
Synthesis of some new benzimidazole‐5(6)‐carboxylic acids
Authors: Göker Hakan , Ölgen Süreyya , Ertand Rahmiye , Akgün HÜLya , Özbey Süheyla , Kendi Engin , Topçu GÜL 
Published: March 2009

AbstractThe title compounds, 1,2‐dialkyl‐benzimidazole‐5(6)‐carboxylic acids34–45were prepared at four steps; 1) preparation of mono amide derivatives1–11by the reaction of methyl 3,4‐diaminobenzoate and substituted phenyl or phenoxyacetic acid chlorides; 2) preparation of the methyl benzimidazolecarboxyl‐ates12–22, with zinc chloride and dry hydrogen chloride gas; 3) alkaline hydrolysis of the esters23–33; and 4) substitution of the imidazole ring with benzyl orp‐fluorobenzyl bromide, in alkali medium. 2‐Aryl‐benzimidazole‐5(6)‐carboxylic acids50–53were preparedviathe oxidative condensation of 3,4‐diaminobenzoic acid and aromatic aldehydes with cupric ion.
Novel heterocyclic systems. Synthesis of 10H‐Pyrrolo[1,2‐b][1,2,5]‐benzothiadiazocine 5,5‐dioxide and related derivatives
Authors: Di Santo Roberto , Costi Roberta , Artico Marco , Massa Silvio 
Published: March 2009

AbstractThe synthesis of 10H‐pyrrolo[1,2‐b][1,2,5]benzothiadiazocine 5,5‐dioxide has been carried out by intramolecular cyclization of 1‐(2‐formamidomethylphenylsulfonyl)‐1H‐pyrrole, prepared from the reaction of 1‐(2‐aminomethylphenylsulfonyl)‐1H‐pyrrole with ethyl formate. Treatment of the last pyrrole derivative with triphosgene afforded 10H‐pyrrolo[1,2‐b][1,2,5]benzothiadiazocin‐12(11H)‐one 5,5‐dioxide, which was also prepared by cyclization of 1‐(2‐methoxycarbamidomethylphenylsulfonyl)‐1H‐pyrrole. Methylation of the 12‐one derivative furnished the corresponding ‐methyl benzothiadiazepine dioxide. 1‐(2‐Aminomethylphenylsulfonyl)‐1H‐pyrrole has been prepared by cleavage of the phthalimido moiety of 1‐(2‐phthalimidomethylphenylsulfonyl)‐1H‐pyrrole, obtained by reacting with potassium phmalimide 1‐(2‐bromomethylphenylsulfonyl)‐1H‐pyrrole. This compound has been obtained starting from 2‐bromomethyl‐benzensulfonamide by Clauson‐Kaas procedure.
Aflatoxin analogues as possible anticoagulants. III
Authors: Mouli G. V. P. Chandra , Giridhar T. , Rao D. Mohan , Reddy R. B. 
Published: March 2009

AbstractThe synthesis of a series of derivatives of 4‐hydroxycoumarin analogues of aflatoxin and a preliminary testing of their anticoagulant activity is described.
A straightforward route to 4H‐1,4‐Benzoxazine‐2‐carbaldehydes by swern oxidation
Authors: Bourlot Anne‐Sophie , Guillaumet Gérald , Mérour Jean‐Yves 
Published: March 2009

AbstractSwern oxidation of saturated (1,4‐benzoxazine‐2‐yl)‐methanols 2 furnished 4H‐1,4‐benzoxazine‐2‐carbaldehydes 3, which possess an α,β ethylenic bond. The reactivity of these compounds was examined.
Furopyridines. XIX. Reaction of furo[2,3‐b]‐, ‐[3,2‐b]‐, ‐[2,3‐c]‐ and ‐[3,2‐c]pyridine with acetic anhydride
Authors: Shiotani Shunsaku , Taniguchi Katsunori , Ishida Toshimasa , In Yasuko 
Published: March 2009

AbstractAcetoxylation of N‐oxide of furo[2,3‐b]‐ 2a, ‐[3,2‐b]‐ 2b, ‐[2,3‐c]‐ 2c and ‐[3,2‐c]pyridine 2d with acetic anhydride afforded compounds substituted normally at the α‐ or γ‐position to the ring nitrogen, 3a, 4a, 4b, 3d, 4d, 8 and 9, and in addition compounds substituted on the furan ring, 5a, 6a, 5b, 6b, 7b, 5c and 7c which were unexpected compounds. The structures of these compounds were established from the ir, nmr and mass spectra, and x‐ray crystal analysis of 5b.
The synthesis and determination of acidic ionization constants of certain 5‐substituted 2‐aminopyrrolo[2,3‐d]pyrimidin‐4‐ones and methylated analogs
Authors: Hoops Geoffrey C. , Park Julie , Garcia George A. , Townsend Leroy B. 
Published: March 2009

AbstractThe acidic ionization constants were determined for a series of 5‐substituted 2‐aminopyrrolo[2,3‐d]‐pyrimidin‐4‐ones and N‐3‐ and N‐7‐methylated analogs thereof. The syntheses of the methylated analogs are also described.
Nitrogen bridgehead compounds. Part 86. Synthesis and reactivity of 7,12‐dihydropyrimido[1′,2′;1,2]pyrido[3,4‐b]indol‐4(6H)‐ones. Debenzologues of rutaecarpine alkaloids
Authors: Hermecz István , Forgó PÉter , Böcskei Zsolt , Fehér Miklós , Kökösi József , Szász György 
Published: March 2009

AbstractA series of 7,12‐dihydropyrimido[1′2′:1,2]pyrido[3,4‐b]mdole‐4(6H)‐ones was prepared by Fischer indolization of 9‐arylhydrazono‐6,7,8,9‐tetrahydro‐4H‐pyrido[1,2‐a]pyrirmdin‐4‐ones. Quantum chemical calculations (ab initio and AM1) indicate that position 3 of 7,12‐dihydropyrimido[1′,2′:1,2]pyrido‐[3,4‐b]indole‐4(6H)‐one can be involved in electrophilic substitutions, while position 2 is sensitive towards nucleophilic attack. Bromination of 6‐methyl‐7,12‐tetrahydropyrimido[1′,2′:1,2]pyrido‐[3,4‐b]indol‐4(6H)‐one 16 with bromine afforded 3‐bromo derivative 25, which was reacted with cyclic amines to give 2‐ammo‐7,12‐dihydropyrirmdo[1′2′:1,2]pyrido[3,4‐b]indol‐4(6H)‐ones 26–30 in an addition‐elimination reaction. Vielsmeier‐Haack formylation of compound 16 gave 12‐formyl 31 and 3,12‐diformyl 32 derivatives (an N‐formyl‐1‐deaza derivative of nauclefidine alkaloid 34) at 60° and 100°, respectively. 3,12‐Diformyl compound 32 was oxidized to 3‐carboxyl derivative 33 with potassium permanganate. The quaternary salt 35, obtained from compound 16 with dimethyl sulfate, suffered a ring opening on the action of aqueous sodium hydroxide. The new compounds have been characterized by elemental analyses uv, 1H nmr and in some cases by 13C ruler, CD spectra and X‐ray investigations.
Acylaminoacetyl derivatives of active methylene compounds. 4
Authors: Hamilakis Stylianos , Kontonassios Demetrios , Sandris Constantine 
Published: March 2009

AbstractMeldrum's acid has been found to be effectively acylated using the imidazolides of N‐protected glycines, X‐NHCH2COOH (X = ‐COPh, ‐COMe, ‐Z, ‐Boc, ‐COOMe and ‐COOEt). The corresponding C‐acylation compounds were isolated in high yields and were readily converted to the N‐protected tetramic acids. It was shown by pmr spectroscopy that these acids exist as the enol tautomers in DMSO‐d6 solution, whereas in deuteriochloroform solution both the enol and keto tautomers can be observed.
Spectroscopic and computational investigation of the ground and low excited states of some symmetrical heterocyclic disulfides
Authors: Stoyanov Stefan , Stoyanova Tatyana , Akrivos Pericles D. , Karagiannidis Petros , Nikolov Peter 
Published: March 2009

AbstractThe electronic absorption and emission spectra of some symmetrical heterocyclic disulfides are investigated. The reversible disulfide — thione transformation in water is discussed in view of the complex equilibrium processes present. UV irradiation and pH influence on the above transformation is also studied. The emission properties at room and low temperature are related to the computed molecular geometries of the ground and low excited states of the compounds.
Photolysis of 2‐azidopyridines. the behavior of 1‐(2‐azido‐6‐chloropyrid‐4‐yl)‐3‐phenylurea, a photoaffinity labeling reagent for probing cytokinin‐binding proteins
Authors: Dias Marylène , Mornet René , Richomme Pascal 
Published: March 2009

AbstractThe photolysis of l‐(2‐azido‐6‐chloropyrid‐4‐yl)‐3‐phenylurea (1) was studied under various conditions. In alcohols or in hexane, complex mixtures of products were obtained. Methoxide anions or diethylamine gave rise in high yield to 1,3‐diazepines resulting from ring enlargement of the intermediate nitrene with addition of one molecule of the nucleophile, and nucleophilic substitution of the chlorine atom. A similar reaction was observed in water, when Pyrex filtered light was used. However, with unfiltered light produced by a powerful lamp, the main reaction was photodechlorination. The reagent 1 is expected to bind covalently to cytokinin‐binding proteins through different ways upon photolysis.