bluuebunny/crossref_metadata_2025 huggingface dataset:
Some novel heterocyclic systems derived from 7‐amino‐2,3‐dihydro‐8‐nitro‐1H‐pyrrolo[1,2‐α]benzimidazole and the corresponding diamine
Authors: Groves Clive L. , Ralph James T. , Temple Arthur F.
Published: April 2009

The preparation of 7‐amino‐2,3‐dihydro‐8‐nitro‐1H‐pyrrolo[1,2‐a]benzimidazole from 1,4‐diacetamido‐2,3‐dinitrobenzene is described. Reaction of this compound with 2,5‐dimethoxytetrahydrofuran produces 2,3‐dihydro‐8‐nitro‐7‐N‐pyrrolo‐1H‐pyrrolo[1,2‐a]benzimidazole, which can be cyclised to produce two new heterocyclic ring systems, 9,10‐dihydro‐8H‐pyrrolo[1,2‐a]pyrrolo(1′,2′:1,2]imidazo[5,4‐f]quinoxaline and 9,10‐dihydro‐8H‐pyrrolo[2,1‐c]pyrrolo[1′,2′:1,2]imidazo[4,5‐h][1,2,4]benzotriazine. The corresponding diamine, 7,8‐diamino‐2,3‐dihydro‐1H‐pyrrolo[1,2‐a]benzimidazole undergoes a variety of condensation reactions to produce several new heterocyclic systems, for example, with formic acid, 1,7,8,9‐tetrahydroimidazo‐[4,5‐e]pyrrolo[2,1‐6]benzimidazole is formed and with diacetyl, 9,10‐dihydro‐2,3‐dimethyl‐8H‐pyrrolo‐[1′,2′:1,2]imidazo[5,4‐y]quinoxaline is obtained.
Correlation of dihedral angles with 13C chemical shifts of quaternary carbon atoms of some phenothiazine derivatives
Authors: Jovanovic Misa V. , Biehl Edward R.
Published: April 2009

A direct relationship between the 13C nmr chemical shifts of the quaternary carbon atoms of the central ring of phenothiazine and the dihedral angle of the respective derivatives has been observed. This correlation allows for the useful and quick estimation of the dihedral angles of novel phenothiazines from readily obtainable 13C nmr solution measurements. In addition, the change in the dihedral angle appears to be directly related to the S‐C4a‐C10a bond angle; however, the C4a‐S‐C5a bond angle is not affected by changes in the dihedral angle. This indicates that the “flattening” of the phenothiazine tricyclic ring system is compensated for by the vertical displacement of the sulfur atom, by changes in hybridization of N10, and by other angular distortions of the middle ring.
The synthesis of a pyrido[2,3‐c]pyridazine: A cinnoline related to 6‐fluoronalidixic acid
Authors: Sanchez Joseph P. , Trehan Ashok K. , Nichols Jeffry B.
Published: April 2009

An analog of the pyrido[2,3‐c]pyridazine ring system, 1‐ethyl‐6‐fluoro‐1,4‐dihydro‐7‐methyl‐4‐oxopyrido‐[2,3‐c]pyridazine‐3‐carboxylic acid (13), related to both Cinoxacin (1) and nalidixic acid (2), has been synthesized. The reductive ring closure of 2‐chloro‐α‐diazo‐6‐methyl‐5‐nitro‐β‐oxo‐3‐pyridinepropanoic acid, ethyl ester (7), proved to be the key reaction providing entry into the ring system.
Access to the 2,3‐dihydropyridazin‐3‐one and as‐triazino[3,4‐a]phthalazine ring systems from 4‐aryl‐2‐oxo‐butanoic acids
Authors: El‐Ashry El‐Sayed H. , Amer Adel , Labib George H. , Abdel Rahman Mohamed M. , El‐Massry Abdel Monem
Published: April 2009

A novel series of 2,3‐dihydropyridazin‐3‐ones 15 were synthesized via condensation between hydrazines and 4‐(p‐chlorophenyl)‐2‐hydroxy‐2‐(2‐oxo‐2‐substituted ethyl)butanoic acids 8 which in turn were prepared by the reaction of substituted benzylpyruvic acids 6 with methyl alkyl(aryl) ketones 7. Dehydration of 8b‐d by a mixture of glacial acetic acid and hydrochloric acid afforded 4‐(p‐chorophenyl)‐2‐(substituted phenacyl)‐2‐butenoic acids 10. Condensation reaction of 10 with hydrazines gave type 15 compounds in good yields. Also, a new series of as‐triazino[3,4‐a]phthalazines 20 was obtained from the reaction of substituted benzylpyruvic acids 6 with hydralazine to give the hydralazones 19 which underwent dehydrative cyclization reaction with PPA to afford 20. Structure assignments are based on 1H, 13C nmr and ir spectra.
Nucleophilic displacements in pyridine rings
Authors: Dunn A. D. , Norrie R.
Published: April 2009

The reactions of halopyridines containing an electron withdrawing group (‐CN, ‐CO2R,‐COMe, ‐NO2) with sulphur nucleophiles is reported.
Synthesis of 4H‐3,3a‐dihydrothiazolo[4,3‐b]quinazolines
Authors: Adegoke Emmanuel A. , Alo Babajide I. , Familoni Oluwole B.
Published: April 2009

Regiospecific synthesis of 4H‐3,3a‐dihydrothiazolo[4,3‐b]quinazolines and 7‐methyl‐4H‐3,3a‐dihydrothiazolo[4,3‐b]quinazolines IVa and IVb is described. The N‐substituted thiazolidinecarboxylic acids Ia and Ib were converted to the corresponding acid chlorides, IIa and IIb but neither reacted with silver trifluoromethanesulphonate. The carboxylic acids Ic and Id were however, decarboxylated to the corresponding iminium ions using phosphorus oxychloride and these afforded the nitroamines IIIa and IIIb. Reductive cyclisation led to the quinazolines IVa and IVb.
Crystal structures of 2,4‐dimethylthioxanthene 10,10‐dioxide, 2,4,9‐trimethylthioxanthene 10,10‐dioxide, and 2,4‐dimethyl‐9‐isopropylthioxanthene 10,10‐dioxide
Authors: Chu Shirley S. C. , Napoleone Vera , Chu Ting L.
Published: April 2009

The structures of 2,4‐dimethylthioxanthene 10,10‐dioxide, 1, 2,4,9‐trimethylthioxanthene 10,10‐dioxide, 2, and 2,4‐dimethyl‐9‐isopropylthioxanthene 10,10‐dioxide, 3, have been determined by x‐ray diffraction. The central ring of the thioxanthene ring system is in a boat conformation. The 9‐methyl substituent in 2 and the 9‐isopropyl substituent in 3 are both in the boat‐axial conformation with respect to the central ring. The folding angles between the planes of the two benzo rings are 136.6°, 142.9°, and 134.3° for 1, 2, and 3, respectively.
Synthesis and reactions of 4‐isopropylidene‐1‐aryl‐3‐methyl‐2‐pyrazolin‐5‐ones
Authors: Deruiter Jack , Carter Deborah Ann , Arledge Wilmer Scott , Sullivan Patrick J.
Published: April 2009

The reactions of 4‐isopropylidene‐1‐aryl‐3‐methyl‐2‐pyrazolin‐5‐ones 4a‐d were investigated under a variety of conditions. In the presence of thiols or piperidine, 4a‐d failed to yield conjugate addition products, presumably due to the steric bulk provided by the two methyl substituents of the isopropylidene side chain. Reaction of 4a‐d with hydrazine derivatives gave the 1‐aryl‐3‐methyl‐2‐pyrazolin‐5‐ones 3a‐d and isopropyl‐hydrazones. Treatment of 4a with potassium cyanide yielded a stable conjugate addition product which exists as a mixture of tautomers in different solvents. Also, oxidation of 4a with hydrogen peroxide gave a spiroepoxide 22, while m‐chloroperbenzoic acid oxidation afforded both the spiroepoxide 22, and a small quantity of a hydroxyspiroepoxide 23.
Research on heterocyclic compounds. XXI. Synthesis of imidazo[2,1‐b]benzothiazole and imidazo[2,1‐b]thiazole derivatives
Authors: Abignente Enrico , De Caprariis Paolo , De Martino Giovanni , Patscot Rosaria
Published: April 2009

The reaction of some 2‐aminobenzothiazoles and 2‐aminothiazoles with ethyl 3‐bromo‐4‐oxopentanoate was investigated with the aim to obtain the corresponding imidazo[2,1‐b]benzothiazole and imidazo[2,1‐b]‐thiazole derivatives, respectively. In some cases, two unexpected side products were obtained together with the required compound and their structures were elucidated: e.g., 2‐aminobenzothiazole reacted with ethyl 3‐bromo‐4‐oxopentanoate to give ethyl 2‐methylimidazo[2,1‐b]benzothiazole‐3‐acetate together with ethyl imi‐dazo[2,1‐b]benzothiazole‐2‐propionate and ethyl 3‐(benzothiazol‐2‐yl)amino‐4‐oxopentanoate.
Reaktivitäut und reaktionswege von methylsubstituierten bisindolylcarbenium‐ionen
Authors: Pindur Ulf , Müller Johann
Published: April 2009

Methyl substituted bisindolylcarbenium ions 1 react with some O‐ and C‐nucleophiles regioselectively. The cations 1b, 1c yield with hydroxide ions the tetraindolyldimethyl ether 4 and with methoxide ions the bisin‐dolylmethoxymethanes 5. Compounds 1a, 1b, 1c react with several methylindoles to isomeric bis‐ and trisin‐dolylmethanes. An electrophilic reactivity order of cations 1 can be derived supporting on the experimental results.
Synthesis and spectral properties of someN‐(2‐benzimidazoyl)‐α‐aminoesters and theirN‐oxides
Authors: Sabri Salim S. , El‐Abadelah Mustafa M. , Yasin Hani A.
Published: April 2009

A series of newN‐(2‐benzimidazol)(S)‐α‐aminoesters and the respectiveN‐oxides have been prepared, and their spectral data discussed. The CD spectra of thealiphaticandaromaticamino ester derivatives of either series show sign reversal for the observed Cotton effect (CE) band. This chiroptical behaviour was rationalized as due to differences in conformational isomerism.
Reactions of 2‐aminobenzenethiols with 4‐hydroxycoumarin, maleic anhydride and p‐chlorobenzoylacetone: A single step synthesis of heterocycles containing the 1,4‐thiazine nucleus
Authors: Gupta R. R. , Gautam R. K. , Kumar Rakesh
Published: April 2009

A single step and convenient synthesis of some heterocycles containing the 1,4‐thiazine nucleus are reported by the condensation and cyclization of substituted 2‐aminobenzenethiols with 4‐hydroxycoumarin, maleic anhydride and p‐chlorobenzoylacetone.
A new synthetic route to 7‐halo‐1‐cyclopropyl‐6‐fluoro‐1,4‐dihydro‐4‐oxoquinoline‐3‐carboxylic acid, an intermediate for the synthesis of quinolone antibacterial agents
Authors: Egawa Hiroshi , Kataoka Masahiro , Shibamori Koh‐Ichiro , Miyamoto Teruyuki , Nakano Junji , Matsumoto Jun‐Ichi
Published: April 2009

Starting from m‐fluorotoluene, 7‐chloro‐6‐fluoro‐ and 6,7‐difluoro‐1‐cyclopropyl‐1,4‐dihydro‐4‐oxoquino‐line‐3‐carboxylic acids, 3 and 16 were synthesized. Compounds 3 and 16 are useful intermediates for the synthesis of a class of quinolone antibacterial agents. The synthetic route involves two processes; i) construction of the quinoline ring by an intramolecular cyclization accompanied by the elimination of a nitro group and ii) introduction of fluorine atom by replacement of a nitro group with potassium fluoride. 7‐(3‐Amino‐1‐pyrroli‐dinyl)‐1‐cyclopropyl‐6‐fluoro‐1,4‐dihydro‐4‐oxoquinoline‐3‐carboxylic acid (18) was prepared from 3 or 16. The antibacterial activity of 18 compares favorably with that of ciprofloxacin (2).
3,6‐Dialkyl‐2‐hydroxypyrazine 1‐oxides as acyl carriers
Authors: Okuwaki Yukari , Inagawa Yukiko , Tamamura Hideo , Suzuki Taeko , Kuwana Hiroko , Tahara Mika , Yuasa Kayo , Ohta Akihiro
Published: April 2009

3,6‐Dialkyl‐2‐hydroxypyrazine 1‐oxides were found to be useful as acyl carriers. Benzoyl derivatives were convenient reagents for benzoylation of amines and hydroxy compounds.
Pyrimidines. 8. chlorination of 6‐methyluracil with phosphorus oxychloride in the presence of trialkyamines
Authors: Gershon Herman , Grefig Anthony , Clarke Donald D. , Gershon Herman
Published: April 2009

The effect of the tertiary amines triethyl, tri‐n‐propyl, and tri‐n‐butylamines on the chlorination of 6‐methyluracil by phosphorus oxychloride was studied. A comparison with the reaction of preformed 2,4‐dichloro‐6‐methylpyrimidine and triethylamine in toluene was made. The reaction in phosphorus oxychloride in the presence of triethylamine afforded low yields of 2‐diethylamino derivative after short heating periods and high yields of the 2,4‐bis(diethylamino) derivative after 188 hours of boiling. Heating the preformed 2,4‐dichloro‐6‐methylpyrimidine in toluene in the presence of triethylamine yielded primarily the 2‐diethylaminopyrimidine along with a small amount of the 4‐diethylamino isomer. After 188 hours, the product mixture was composed of 87% 2‐diethylamino and 13% of 4‐diethylamino isomers. Although substituent orientation was essentially the same, the yields of products seem to have been influenced by the dielectric constants of the solvents.

Tri‐n‐propylamine in phosphorus oxychloride yielded solely the dichloropyrimidine, even after 188 hours of boiling, and is recommended as the amine of choice in such chlorination reactions. Tri‐n‐butylamine was the same after 48 hours, but 4% of 4‐di‐n‐butylaminopyrimidine was found after 188 hours of heating.
A heterocyclic analog of leucine‐enkephalin
Authors: Carr Albert A. , Dudley Mark W. , Huber Edward W. , Kane John M. , Miller Francis P.
Published: April 2009

A series of di‐, tri‐, tetra‐ and pentapeptide analogs of leucine‐enkephalin have been prepared in which the initial tyrosinylglycine fragment has been replaced by the 5,6‐dihydro‐5,5‐dimethyl‐2‐oxo‐3‐phenyl‐1(2H)‐pyrazineacetic acid moiety.
Nonaqueous diazotization of 4‐amino‐3‐arylisothiazole‐5‐carboxylate esters
Authors: Beck James R. , Gajewski Robert P.
Published: April 2009

4‐Amino‐3‐arylisothiazole‐5‐carboxylate esters are converted to the corresponding desamino, chloro, bromo, and iodo esters by processes involving nonaqueous diazotization. These related procedures open up the possibility for the conversion of readily available heterocyclicortho‐amino esters and nitriles to related heterocyclic derivatives, which are not easily obtained by alternate routes.
Reactivity of aryl‐ and heteroarylmalonates against ortho‐dinucleophiles. Triaryl(heteroaryl)methane synthesis
Authors: Ramos Teresa , Avendaño Carmen , Elguero JosÉ
Published: April 2009

Condensations of several aryl(heteroaryl)malonates 1 and ortho‐dinucleophiles are studied as a possible synthetic approach to aryl(heteroaryl)bisheteroarylmethanes 2.
On mechanistic aspects of 5‐deazaflavin dependent dehydrogenation of alcohol
Authors: Tanaka Kiyoshi , Kimura Teiji , Yoneda Fumio , Ijuin Mineko , Sakuma Yoshiharu
Published: April 2009

The reaction of 5‐deazaflavins with alcoholates was investigated and the direct hydride equivalent transfer from C1 of alcoholates to C5 of 5‐deazaflavins was confirmed by chemical methods. 5‐Alkoxy‐10‐butyl‐3‐methyl‐5‐deazaflavins were synthesized by treatment of 10‐butyl‐5‐chloro‐3‐methyl‐5‐deazaflavin with the corresponding alcoholates. The 5‐alkoxy‐5‐deazaflavins were reduced by sodium borodeuteride or sodium hydro‐sulfite in deuterium oxide or monodeuteriomethanol to give 10‐butyl‐3‐methyl‐1,5‐dihydro‐5‐deazaflavin‐5,5‐D2 exclusively. 3,10‐Dimethyl‐5‐deazaflavin radical anion was detected by esr technique on treatment of 3,10‐dimethyl‐5‐deazaflavin with potassium in DMF. From the above reactions, a mechanism of 5‐deazaflavin dependent dehydrogenation of alcoholate was proposed.
Nonaqueous diazotization of 5‐amino‐1‐aryl‐1H‐pyrazole‐4‐carboxylate esters
Authors: Beck James R. , Gajewski Robert P. , Lynch Michael P. , Wright Fred L.
Published: April 2009

5‐Amino‐1‐aryl‐1H‐pyrazole‐4‐carboxylate esters are converted to the corresponding desamino, chloro, bromo, iodo, and methylthio esters by processes involving nonaqueous diazotization. Diazotizing agents are alkyl nitrites except in the case of chlorine where nitrosyl chloride is used. Evidence is presented that the latter reagent leads to the formation of cationic rather than radical intermediates.
Diphenyl cyancarbonimidate and dichlorodiphenoxymethane as synthons for the construction of heterocyclic systems of medicinal interest
Authors: Lee Webb R. , Eggleston Drake S. , Labaw Clifford S. , Lewis Joseph J. , Wert K.
Published: April 2009

Simple high yield methods for the preparation of heterocyclic N‐cyanoguanidines (including the anti‐ulcer drug cimetidine), substituted triazoles, benzimidazoles and oxadiazoles with anti‐histaminic (H2) activity from the title compounds are described.
Synthesis of 10‐propargylfolic acid from 2‐amino‐6‐(bromomethyl)‐4(1h)‐pteridinone
Authors: Piper James R. , Mccaleb George S. , Montgomery John A.
Published: April 2009

6‐(Bromomethyl)‐2,4‐pteridinediamine hydrobromide (1) is readily converted to 2‐amino‐6‐(bromomethyl)‐4(1H)‐pteridinone hydrobromide (2) by treatment with 48% hydrobromic acid. Compound 2 is of interest for direct attachment of the (2‐amino‐3,4‐dihydro‐4‐oxo‐6‐pteridinyl)methyl group to appropriate side‐chain precursors of analogues of folic acid, particularly those bearing functional groups incompatible with conditions required for hydrolytic deamination of the corresponding 2,4‐diaminopteridine analogues. An example of the use of 2 in this connection is demonstrated through synthesis of 10‐propargylfolic acid.
Synthesis of some hydroxy and methoxymethyl derivations of 1H‐pyrazolo[5,1‐c]‐1,2,4‐triazoles
Authors: Goddard John D.
Published: April 2009

Electrophilic hydroxylation of a pyrazolotriazole with a mixture of trifuoroacetic attack of methanolic hydroxide ion on a dichloropyrazolotriazole gave a 6‐methoxymethylpyrazolotriazole by a mechanism involveing a cyclopropane intermediate.
Reductive cyclization of ketoesters utilizing sodium cyanoborohydride: Synthesis of γ‐ and δ‐lactones
Authors: Podraza Kenneth F.
Published: April 2009

A new one pot procedure to synthesize γ‐ and δ‐lactones, in a 76‐84% yield, is accomplished by the reductive cyclization of 1,4‐ and 1,5‐ketoesters, utilizing sodium cyanoborohydride. The procedure is generally applicable to a wide variety of ketoesters with the exception of the ethyl ester of alkyl 1,5‐ketoesters and α,β‐unsaturated 1,4‐ and 1,5‐ketoesters.
1,3‐Dipolar cycloaddition reactions of nitrilimines with 1‐aroyl‐4,5‐dihydro‐3,4,4‐trimethyl‐5‐methylene‐1H‐pyrazoles. Synthesis of 6‐aroyl‐8,9,9‐trimethyl‐1,2,6,7‐tetrazaspiro[4.4]nona‐2,7‐dienes
Authors: Papadopoulos Stelios , Stephanidou‐Stephanatou Julia
Published: April 2009

From the 1,3‐dipolar cycloaddition reactions of 5‐methylene‐1H‐pyrazoles 3 with N‐arylnitrilimines the novel spiro‐cycloadducts 4 were isolated, in addition to the corresponding 5‐(2‐aroylhydrazono‐1,1‐dimethylpropyl)‐1H‐pyrazoles 5. These pyrazoles 5 were the only products from the reactions of 3 with N‐methylnitrilimine 2d. The chemical behaviour of the spiro‐cycloadducts 4 was also examined.
Fused s‐triazino heterocycles. XIV 8H‐1,3,7,8,9,10c‐hexaazacyclopenta[a]phenalene, 1,3,7,8,10,11c‐hexaazabenz[de]anthracene and 13H‐4,6,8,13a, 13c‐pentaazabenzo[de]naphthacene, three new ring systems
Authors: Shaw John T. , Fair Mark C.
Published: April 2009

The synthesis of the title compounds 3,4 and 5 is described, using 7,9‐dibromo‐5‐tribromomethyl‐2‐t‐butyl‐4‐cyano‐1,3,6,9b‐tetraazaphenalene 2a as starting material. The key intermediates are 7,9‐dibromo‐2‐t‐butyl‐4‐cyano‐5‐hydrazino‐1,3,6,9b‐tetraazaphenalene 2b, 5‐benzamidino‐7,9‐dibromo‐2‐t‐butyl‐4‐cyano‐1,3,6,9b‐tetraazaphenalene 2c, and 7,9‐dibromo‐2‐t‐butyl‐5‐(2‐carboxyanilino)‐4‐cyano‐1,3,6,9b‐tetraazaphenalene 2e.
Synthesis of 3‐(2‐chloro‐5‐nitroanilino and 4‐nitroanilino)‐1‐(2,4,6‐trichlorophenyl)‐2‐pyrazolin‐5‐ones
Authors: Kim Chang‐Kyu , Debellis Francesco , Maggiulli Cataldo A.
Published: April 2009

A new synthesis of 3‐anilino‐1‐aryl‐2‐pyrazolin‐5‐ones in which the pyrazolinone ring is built via NN bond formation is described. 2‐Cyano‐2′,4′,6′‐trichloroacetanilide 1 was converted to imino ether hydrochloride 2 which was reacted with anilines in methanol to produce N‐arylimino ether 3a,b. Reaction of these N‐arylimino ethers with hydroxylamine gave N‐arylamidoximes 4a,b. An 1,2,4‐oxadiazol‐5‐one 6a was prepared from the N‐arylamidoxime 4a and subjected to base‐induced rearrangement. The desired 3‐anilino‐pyrazolinone 7a was obtained only in a very low yield. However, O‐acetylation of the N‐arylamidoximes 4a,b followed by acid‐catalyzed ring closure and rearrangement in the presence of excess acetic anhydride gave a mixture of N‐acetylanilinopyrazolinones (e.g. 10) and 4‐acetyloxy‐3‐N‐acetylanilinopyrazoles (e.g. 12) which upon acid hydrolysis afforded the 3‐anilinopyrazolinones 7a,b in better yield.
The insertion and extrusion of heterosulfur bridges. XIII. Syntheses and structural studies of nitrophenanthro[4,5‐bcd]thiophenes
Authors: Klemm L. H. , Tsuchiya Reiko , Wong Eric K. L. , Stevens Michael P. , Lu Jennifer J. , Klopfenstein C. E.
Published: April 2009

A simplified procedure for sulfur bridging of phenanthrene (2a) with hydrogen sulfide and a catalyst, but without solvent, is described. The product, phenanthro[4,5‐bcd]thiophene (1a), undergoes nitration at 25° or 60° in acetic anhydride to give mixtures (56–79%) of 1‐nitro‐1a and 3‐nitro‐1a in varying ratios. Reductive acetylation of these nitro derivatives gives 1‐ and 3‐acetylamino‐1a (93% and 33%). Hydrodesulfurization of the former amide produces crude 1‐acetylamino‐2a. Positions of substitution are assigned primarily on the basis of nmr chemical shifts of protons ortho or peri to the nitro substituent, and are consistent with calculations of reactivity indices by simple Hückel molecular orbital theory.
Cycloaddition of oxetanes with heterocumulenes catalyzed by organotin iodide‐lewis base complex
Authors: Shibata Ikuya , Imoto Takafumi , Baba Akio , Matsuda Haruo
Published: April 2009

A series of 2‐oxazinones 1‐8 were synthesized from the cycloaddition reactions of oxetanes with isocya‐nates by utilizing the complex of diphenyltin diiodide with hexamethylphosphoric triamide (HMPA) as a catalyst. Moreover, the reactions with carbodiimides proceeded under milder conditions with the same catalyst system, and gave 2‐iminooxazines, 9 and 10, in high yields.
Reactions of lithium tributyl heteroaryl borates with allylic bromides in the presence of copper(I) cyanide
Authors: Ishikura Minoru , Kamada Machiko , Oda Izumi , Ohta Tsukasa , Terashima Masanao
Published: April 2009

The reaction of various lithium tributylheteroarylborates with allylic bromides in the presence of copper(I) cyanide furnished the regioselective allylation at the heteroaryl ring.
Amidomethylation of indoles and cyclisations to spiro[pyrrolo[4,3,2‐de]isoquinoline‐3,4′‐piperidines]
Authors: Carter Christine , Freter Kurt R. , Kriwacki Richard W. , Leonard Scott F. , Phil Pitner T.
Published: April 2009

4‐Aminomethylindoles react with aldehydes and ketones to form pyrrolo[4,3,2‐de]isoquinolines. The structures of starting materials and end products were determined using 1D and 2D 1H nmr techniques.
Nitrogen bridgehead compounds. Part 71. Chiroptical properties of 9‐halo derivatives of 6,7,8,9‐tetrahydro‐4H‐pyrido[1,2‐a]pyrimidin‐4‐one and its 3‐carboxy derivative
Authors: Kajtár Márton , Kajtár Judit , Hermecz István , Breining Tibor , Mészáros Zoltán
Published: April 2009

Earlier assignments [2] relating to the CD bands of 6,7,8,9‐tetrahydro‐4H‐pyrido[1,2‐a]pyrimidin‐4‐ones were utilized to explain the chiroptical properties of their 9‐halogenated derivatives. The signs of the most characteristic CD bands proved to be determined by the axial substituents in the benzylic position to the inherently achiral pyrimidinone chromophore.
Synthesis, structure elucidation and chemotherapeutic activity of 6‐substituted 1‐ethyl‐1,4‐dihydro‐7‐[(1‐imidazolyl)phenylmethyl]‐ 4‐oxo‐3‐quinolinecarboxylic acids
Authors: Frigola Jordi , Colombo Augusto , Más Josep , Parés Juan
Published: April 2009

The synthesis, structure elucidation and chemotherapeutic activity of novel 3‐quinolinecarboxylic acid derivatives are reported. These derivatives are characterized by a group (1‐imidazolyl)phenylmethyl attached to the 7‐position and chloro 10a, fluoro 10b or methoxy 10c appended to the 6‐position.
Proton‐ionizable crown compounds. 9. Synthesis and structural studies of new 14‐crown‐4 compounds containing a pyridine or 4‐pyridone subcyclic unit
Authors: Bradshaw Jerald S. , Guynn John M. , Wood Steven G. , Wilson Bruce E. , Kent Dalley N. , Izatt Reed M.
Published: April 2009

Four new 14‐crown‐4 macrocyclic ligands containing either a pyridine or a 4‐pyridone subcyclic unit have been prepared. Two of the 4‐pyridono‐crowns contained lipophilic hydrocarbon substituents. The starting octyl‐ and benzyl‐substituted 4‐oxa‐1,7‐heptanediols were prepared from the 2‐octyl‐ or 2‐benzyl‐1,3‐propane‐diol. When the two substituted 4‐oxa‐1,7‐heptanediols were treated with tosyl chloride, both the expected 2‐substituted‐4‐oxaheptane‐1,7‐ditosylates and the ditosylate of the dimeric diol were isolated. X‐ray structure determinations were carried out on two of the new 14‐crown‐4 compounds.
Selected reactions on the o‐aminonitrile system of substituted pyrroles
Authors: Eger Kurt , Pfahl Johannes Georg , Folkers Gerd , Roth Hermann J.
Published: April 2009

The synthesis of the difficult to obtain pyrrolo[2,3‐d]pyrimidine‐2,4‐diamine (4) is reported. Furthermore, some unexpected reactions on the 2‐aminopyrrole‐3‐carbonitrile system are described 15‐17.
The oxidation of 6‐ and 7‐aryl‐4(3h)‐pteridinones by immobilized arthrobacter M‐4 cells containing xanthine oxidase
Authors: De Meester Johan W. G. , Van Der Plas Henk C. , Middelhoven Wouter J.
Published: April 2009

The preparation of 6‐ and 7‐(pX‐phenyl)‐4(3H)‐pteridinones (X = H, CH3, OCH3) is described. The oxidation of these compounds by (immobilized) Arthrobacter M‐4 cells containing xanthine oxidase has been studied. The oxidation monitored by uv spectroscopy usually goes fast, except for 7‐(pX‐phenyl)‐4(3H)‐pteridinones (X = CH3, OCH3), which are slowly oxidized. With bacterial cells immobilized in gelatine crosslinked with glutaraldehyde small laboratory‐scale oxidations were carried out. Based on spectral data the products of the oxidation reactions are 6‐ and 7‐aryllumazines.
Crystal structure and tautomerism in 4‐phenylisoxazoles with two potential hydroxyl groups at positions 3 and 5
Authors: Zvilichovsky Gury
Published: April 2009

The crystal structure of 4‐phenyl‐3‐hydroxyisoxazol‐5‐one semihydrate exhibits an exceptional hydrogen bonded polymeric structure with a unit cell of 8 molecules. The hydrogen bonds stretch out, using the oxohydroxy groups in positions 3 and 5 in the direction of one axis and along a perpendicular direction the layers are stitched together by water molecules. The layers are stitched by using four hydrogen bridges of water molecules, the heterocyclic ring nitrogen as well as the oxygen at position 5. Tautomerism of this moiety in solution is discussed, in light of some new dialkylation products. The state in which these products exist in solution depends on the solvent. A zwitterionic tautomer is present in ether. In some alkylation conditions, the predominant dialkylation product is the N,N‐disubstituted betaine (Anhydro‐2,2‐dialkyl‐3(5)‐oxo‐5(3)hydroxy‐4‐phenylisoxazolonium hydroxide). Study of tautomerism in polar and protic solvent is unreliable owing to associations and dissociation phenomena.
2,3,4,9‐Tetrahydro‐1H‐pyrido[3,4‐b]indoles. II. Reversible transformation of 1‐alkyl‐2‐(4,9‐dihydro‐3H‐pyrido[3,4‐b]indol‐1‐yl)cyclohexanol into 1‐alkylidene‐2,3,4,9‐tetrahydro‐1H‐pyrido[3,4‐b]indoles
Authors: Bobowski George
Published: April 2009

Treatment of 2‐(4,9‐dihydro‐3H‐pyrido[3,4‐b]indol‐1‐yl)‐1‐methylcyclohexanol (2a) with acetic anhydride or methyl isocyanate gave 2‐acetyl‐2,3,4,9‐tetrahydro‐1‐(6‐oxoheptylidene)‐1H‐pyrido[3,4‐b]indole (3) or 1,3,4,9‐tetrahydro‐N‐methyl‐1‐(6‐oxoheptylidene)‐2H‐pyrido[3,4‐b]indole‐2‐carboxamide (4), respectively. Simpler analogues, 1‐alkyl‐4,9‐dihydro‐3H‐pyrido[3,4‐b]indoles, 7, subjected to identical reaction conditions, gave 2‐acetyl‐1‐alkylidene‐2,3,4,9‐tetrahydro‐1H‐pyrido[3,4‐b]indoles8 and 1,3,4,9‐tetrahydro‐N‐methyl‐1‐alkyli‐dene‐2H‐pyrido[3,4‐b]indole‐2‐carboxamides 9, respectively. A limited lanthanide shift reagent study to determine stereochemical assignments was also performed.
Synthesis of methyl derivatives of 8‐desmethylxanthyletine and 8‐desmethylseseline, potential antiproliferative agents
Authors: Rodighiero P. , Manzini P. , Pastorini G. , Bordin F. , Guiotto A.
Published: April 2009

A number of new methyl derivatives of pyranocoumarins, related to 8‐desmethylxanthyletine and to 8‐desmethylseseline, were synthesized. The syntheses were performed by cyclization in boiling N,N‐diethyl aniline of the propargyl or methylpropargyl ethers of the appropriate methyl derivatives of 7‐hydroxycou‐marin. Methyl groups have been introduced into positions which look most promising for enhancement of the photoreactivity of the compounds towards DNA.
Observations sur l'hydrolyse d'acétals dihydropyranniques
Authors: Thuy Vu Moc , Maitte Pierre
Published: April 2009

L'hydrolyse des acétals dihydropyranniques par l'acide sulfurique conduit à des cyclohexénones, mais l'emploi de p.toluène sulfonate de pyridinium permet d'isoler les δ‐cétoaldéhydes, qui ne se crotonisent pas dans ces conditions.
A novel acyclic addition of ketenes to oxazoles/oxazolines
Authors: Nyce P. , Puar M. S. , Gala D. , Jaret R. S.
Published: April 2009

The addition of n‐butyryl chloride (1) to 5‐phenyloxazole (6) or 4,5‐dihydro‐5‐methyl‐4‐[(4′‐methylphenyl)‐sulfonyl]oxazole (8) in the presence of triethylamine lead to 1‐(5′‐phenyloxazol‐2′‐yl)‐1‐buten‐1‐yl butanoate (7) and 1‐(5′‐methyl‐4′‐[4″‐methylphenylsulfonyl]4′,5′‐dihydrooxazol‐2′‐yl)‐1‐buten‐1‐yl butanoate (9), respectively.
Synthesis of thiabenzene oxides and azathiabenzene oxides
Authors: Tominaga Yoshinori , Hidaki Shozo , Matsuda Yoshiro
Published: April 2009

Fused thiabenzene oxide, 2‐methyl‐4‐methylthiobenzo[b]thieno[3,2‐c]thiapyran 2,5,5‐trioxide (2) was synthesized by the reaction of 2,3‐dihydro‐2‐bis(methylthio)methylene‐3‐oxobenzo[b]thiophene 1,1‐dioxide (1) with trimethyl sulfoxonium iodide in the presence of sodium hydride in tetahydrofuran. Similarly, fused azathiabenzene oxide, 2‐methyl‐4‐methylthiobenzo[b]thieno[2,3‐c][1,2]thiazine 2,5,5‐trioxide (3) was prepared from 1 and sulfoximine in good yield.
Synthèse d'analogues furanniques et nitro‐2 furanniques du diméthyl‐7,12 benzanthracène
Authors: Bilger Christine , Demerseman Pierre , Royer René
Published: April 2009

On décrit les voies d'accès aux formyl‐1 hydroxy‐2 méthyl‐9 anthracène et formyl‐1 hydroxy‐2 diméthyl‐9,10 anthracène. Ces deux aldéhydes ortho‐hydroxylés sont transformés en anthra[2,1‐b]furannes mono‐ou diméthylés, ainsi que les acides et esters correspondants, par condensation avec le bromoacétate d'éthyle. Ils donnent par ailleurs des nitro‐2 anthra[2,1‐b]furannes mono‐ou diméthylés par traitement au bromonitrométhane, suivi de chauffage dans le toluène en prèsence d'acide para‐toluène sulfonique.
Regioselectivity in dipolar cycloaddition reactions of N‐phenylcinnamonitrilimine
Authors: Hassaneen Hamdi M. , Farag Ahmed M. , Shawali Ahmad S. , Algharib Mohamed S.
Published: April 2009

The regioselectivity of the cycloadditions of α,β‐unsaturated nitrilimine derived from N‐phenylcinnamo‐hydrazidoyl chloride 2 to C = Se, C = S and C = C double bonds of the resonance stabilized selenocyanate and thiocyanate anions, enol tautomer of dibenzoylmethane and benzalacetophenone was investigated. The results indicate that the reactions studied are dipole‐LUMO‐dipolarophile‐HOMO controlled and that the larger orbital coefficient in the LUMO of N‐phenylcinnamonitrilimine is on the carbon atom bearing the styryl group. The structures of the cycloadducts were assigned and confirmed on the basis of their elemental analyses and spectra.
Regioselective syntheses of 2‐amino‐4,5‐dialkylthiophene‐3‐carboxylates and their conversion to 3,4‐dihydro‐4‐oxothieno[2,3‐d]pyrimidine‐2‐carboxylates
Authors: Madding Gary D. , Thompson Michael D.
Published: April 2009

The synthesis of 3,4‐dihydro‐4‐oxothieno[2,3‐d]pyrimidine‐2‐carboxylates via acid catalyzed reactions of various 2‐aminothiophene‐3‐carboxylates with activated nitriles is presented. The requisite thiophenes were prepared regioselectively by methods which represent improvements over previously published procedures.
Heterocycles. Part X. Synthesis of new pyrimidine systems
Authors: El‐Rayyes N. R. , Ramadan H. M.
Published: April 2009

Selected aryl aldehydes I were reacted with 1‐benzosuberone to give the corresponding 2‐arylidene‐1‐ben‐zosuberones II. Condensation of these chalcones with urea and thiourea revealed the formation of the corresponding substituted pyrimidin‐2‐ones III, and pyrimidine‐2‐thiones IV respectively. The structure of all products was substantiated by chemical and spectral methods.
Pteridines, LXXXIV. Synthesis, reactivity and properties of 1,3‐dimethyllumazine‐6‐ and 7‐carboxaldehyde derivatives
Authors: Kang Yonghan , Soyka Rainer , Pfleiderer Wolfgang
Published: April 2009

Convenient syntheses of 1,3‐dimethyllumazine‐6‐ (7) and ‐7‐carboxaldehyde (19) are described. The reactivity of the carboxaldehyde group has been investigated by oxidations, reductions and various carbonyl reactions forming a series of new derivatives. The newly synthesized compounds were characterized by elemental analysis, uv and 1H‐nmr spectra.
Reaction of ketenes with N,N‐disubstituted α‐aminomethyleneketones. XX. Synthesis of 2H‐pyrano[2,3‐f]quinazoline derivatives
Authors: Mosti Luisa , Menozzi Giulia , Schenone Pietro
Published: April 2009

The polar 1,4‐cycloaddition of dichloroketene to N,N‐disubstituted (E)‐6‐aminomethylene‐7,8‐dihydro‐(2‐methyl)(2‐phenyl)quinazolin‐5(6H)‐ones III, prepared in good yields from 7,8‐dihydro‐(2‐methyl)‐(2‐phenyl)quinazolin‐5(6H)‐ones via their 6‐hydroxymethylene derivatives I and II, gave in satisfactory to excellent yields N‐N‐disubstituted 4‐amino‐3,3‐dichloro‐3,4,5,6‐tetrahydro‐(8‐methyl)(8‐phenyl)‐2H‐pyrano‐ [2,3,‐f]quinazolin‐2‐ones IV, which are derivatives of the new heterocyclic system pyrano[2,3‐f]quinazoline. This cycloaddition occurred both in the case of aliphatic and aromatic N‐substitution only with 2‐phenyl‐enaminones III, whereas with 2‐methyl derivatives III the reaction took place only in the case of aromatic N‐monosubstitution.

Dehydrochlorination of IV with DBN afforded, generally in excellent yields, N,N‐disubstituted 4‐amino‐3‐chloro‐5,6‐dihydro‐(8‐methyl)(8‐phenyl)‐2H‐pyrano[2,3‐y]quinazolin‐2‐ones, which were dehydrogenated with DDQ to give N,N‐disubstituted 4‐amino‐3‐chloro‐(8‐methyl)(8‐phenyl)‐2H‐pyrano[2,3‐f]quinazolin‐2‐ones in excellent yields.
Benzodioxines‐1,4 disubstituées en position 2,3 par des groupements pharmacophores
Authors: Coudert Gérard , Borredon‐Watrin Corinne , Guillaumet Gérald
Published: April 2009

Afin d'obtenir des composés présentant à la fois des propriétés α et β adrénolytiques, nous avons préparé des benzodioxines‐1,4 disubstituées sur l'hétérocycle par des groupements susceptibles d'introduire les activités recherchées.
Synthetic Approaches to cularines. III. Nucleophilic addition and substitution
Authors: De Lera Angel Rodríguez , Sa á José M. , Suau Rafael , Castedo Luis
Published: April 2009

Attempts to induce the formation of the dibenzoxepine ring of cularine compounds by generating an electron‐deficient system in ring C of an 8‐hydroxybenzylisoquinoline met with failure. Attack by C‐8 phenol on a “p‐quinone methide” intermediate afforded benzofurans 16, which it has been suggested are intermediates in the biogenesis of quettamines. Among the nucleophilic substitution reactions tried, only that based on a phenoxide attack on a benzyne intermediate (generated by dimsyl sodium treatment of a 2′‐bromo‐8‐hydroxybenzylisoquinoline) afforded the dibenzoxepine nucleus of tetradehydrocularines 25 and 27. Competing N‐attack afforded the indolizine skeleton present in 24 and 26. From compounds 25 and 27, the corresponding cularines, cularimines and oxocularines were obtained.
Asymmetrical porphyrins. I. Synthesis, characterization and physicochemical properties of phenyl/4‐benzyloxyphenyl 5,10,15,20‐substituted porphyrins
Authors: Datta‐Gupta N. , Malakar D. , Rice Lesa , Rivers Sheila
Published: April 2009

A complete series of five phenyl/4‐benzyloxyphenyl 5,10,15,20‐substituted porphyrin has been synthesized, characterized by analysis, Rf values, and proton‐nmr spectroscopy (pmr). Their physicochemical properties, namely ir spectra, absorption spectra, emission spectra, excited state life‐times, pK3 values, reduction potentials, and kinetics of Cu(+2) insertion, have been determined. Attempts have been made to correlate these physicochemical properties with the structures of the porphyrins.
Reaction of sulfenes with heterocyclic N,N‐disubstituted α‐aminomethyleneketones. XIII. Synthesis of 1,2‐oxathiino[6,5‐f]quinazoline derivatives
Authors: Menozzi Giulia , Bargagna Alberto , Mosti Luisa , Schenone Pietro
Published: April 2009

The 1,4‐cycloaddition of sulfene to N,N‐disubstituted (E)‐6‐aminomethylene‐7,8‐dihydro‐(2‐methyl)‐(2‐phenyl)quinazolin‐5(6H)‐ones I gave N,N‐disubstituted 4‐amino‐3,4,5,6‐tetrahydro‐(8‐methyl) (8‐phenyl)‐1,2‐oxathiino[6,5‐f]quinazoline 2,2‐dioxides II, which are derivatives of the new heterocyclic system 1,2‐oxathiino[6,5‐f]quinazoline. With 2‐phenylenaminones Id‐h, the cycloaddition occurred, generally in satisfactory yields, both in the case of aliphatic N,N‐disubstitution and aromatic N‐monosubstitution, whereas with 2‐methyl enaminones Ia‐c the reaction took place in low yields only in the case of aliphatic N,N‐disubstitution. Also the reaction of 2‐phenyl enaminones Id‐g with chlorosulfene occurred as with sulfene, giving a mixture of cycloadducts which were dehydrochlorinated in situ with DBN to afford N,N‐di‐substituted 4‐amino‐5,6‐dihydro‐8‐phenyl‐1,2‐oxathiino[6,5‐f]quinazoline 2,2‐dioxides III generally in satisfactory yields. Compounds III could not be dehydrogenated either by DDQ in boiling benzene or by palladium on carbon in boiling p‐cymene.
Nitrogen bridgehead compounds. Part 69. Studies on quinolizine derivatives. Part 3. Infrared and 1H NMR spectroscopic studies of quinolizine derivatives and their monocyclic tautomers
Authors: Schwartz Angéla , Pál Zoltán , Szabó László , Hermecz István , Mészáros Zoltán
Published: April 2009

Infrared and 1H nmr spectra of 4‐oxo, 1, and 4‐imino, 2, quinolizine derivatives or their monocyclic tautomers 3, 4 have been comparatively studied. The number of ethoxycarbonyl groups, the signals of the hetero proton, the C(9)‐H, and the C(6)‐CH3 group in the 1H nmr spectrum, moreover the N‐H stretching vibration bands proved to be diagnostically important for monocyclic or bicyclic as well as for 4‐oxo or 4‐imino structures. A weak intramolecular hydrogen bridge in compounds 2b and 2f, a strong chelate type hydrogen bridge in 4E and 4F=G could have been demonstrated as well.
A facile synthesis of pyrrolo[1,2‐a]pyrimidines and pyrrolo[1,2‐a]imidazoles
Authors: Ross John R. , Vishwakarma Lal C. , Sowell J. Walter
Published: April 2009

The one‐step synthesis of 8‐t‐butoxycarbonyl‐6,7‐dimethyl‐2‐oxo‐1,2,3,4‐tetrahydropyrrolo[1,2‐a]pyrimidine from acetyl methyl carbinol, 3‐aminopropionic acid, and t‐butyl cyanoacetate is reported. Utilizing a similar technology under basic conditions, 7‐substituted 5,6‐dimethyl‐2‐oxo‐2,3‐dihydro‐(1H)‐pyrrolo[1,2‐a]imidazole is synthesized from acetyl methyl carbinol, ethyl glycinate, and the appropriate acetonitrile.
Synthesis and spectra of some triazolo and triazinophthalazines of possible hypotensive activity
Authors: Allah Hassan M. Faid , Soliman Raafat
Published: April 2009

Cyclization of hydralazine 1 with acid chlorides or ethyl cyanoacetate gave the appropriate s‐triazolo derivatives, while with ketoesters or 1,2‐dicyclohexanedione it afforded the as‐triazino derivatives. Reaction of 1 with ketosteroids yielded hydrazones. Preliminary cardiovascular testing revealed possible hypotensive activity of some of these derivatives.
Synthesis of 1‐ and 3‐amino‐5‐t‐butyl‐1H‐ and ‐3H‐v‐triazolo[4,5‐d]pyrimidines as hetaryne precursors
Authors: Tielemans Michel , Christophe Daniel , Promel Robert
Published: April 2009

The synthesis of the title compounds 6 and 8 has first been accomplished by reaction of O‐mesitylsulfonyl‐hydroxylamine with 5‐t‐butyl‐3H‐v‐triazolo[4,5‐d]pyrimidine (5) whose preparation is reported in detail. However the preferred route for the synthesis of the 3‐amino derivative 8 is based upon the preparation of 3‐benzylideneamino‐5‐t‐butyl‐3H‐v‐triazolo[4,5‐d]pyrimidine (10), followed by the removal of the benzylidene protecting group. This critical step was effected by treatment of 10 with dilute hydrochloric acid, in the presence of 2,4‐dinitrophenylhydrazine.

The diazotization of 5‐amino‐4‐hydrazino‐2‐t‐butylpyrimidine gave predominantly the tetrazolo[1,5‐c]‐pyrimidine 13 along with a small amount of compound 8.
The reaction of β‐aminoenones with substituted acetonitriles. Regiospecific synthesis of 2(1H)‐pyridones
Authors: Alberola Angel , Andrés Celia , Ortega Alfonso González , Pedrosa Rafael , Vicente Martina
Published: April 2009

Unsymmetrically substituted β‐aminoenones react with malononitrile, cyanomethylphenylsulfone, benzoyl‐acetonitrile and ethyl cyanoacetate, in very mild conditions, to yield regiospecifically 3‐functionalized 2(1H)‐pyridones in high yields.
Synthesis of some furochromonesulfonamide derivatives with potential pharmacological activity
Authors: Elgamal M. Hani A. , Shalaby Nagwa M. M. , Duddeck Helmut , Rosenbaum Doris
Published: April 2009

A number of visnagin‐9‐sulfonamides 1‐3 have been prepared. In two instances side‐products have been isolated in which the γ‐pyrone ring is opened. All compounds were characterized by high‐field 1H and 13C nmr and mass spectra.
Synthesis of 2′,3′‐dihydrospiro[benzofuran‐2(3H),4′(1′‐H)isoquinoline]s. A novel heterocyclic ring system
Authors: Klein Joseph T. , Davis Larry , Effland Richard C.
Published: April 2009

The synthesis of a novel 2′,3′‐dihydrospiro(benzofuran‐2(3H),4′(1′H)isoquinoline] ring system (IV) by a nucleophilic aromatic fluoride displacement‐cyclization is described. Preparation of various derivatives of IV as well as the precursor 4‐(2‐fluorobenzyl)‐1,2,3,4‐tetrahydro‐4‐isoquinolinols is also described.
Observations on the reduction of aryl nitro groups with palladium‐sodium borohydride
Authors: Smith William B.
Published: April 2009

The reduction of aryl nitro groups by the palladium‐sodium borohydride system can be controlled in some instances to give products differing from those of catalytic hydrogenation. With six equivalents of borohydride added to the catalyst 2,2′‐dinitrobiphenyl formed only 2,2′‐diaminobiphenyl. With added sodium hydroxide and varying amounts of borohydride and catalyst, the reduction can be controlled to give benzo[c]cinnoline, benzo[c]cinnoline 5‐oxide or benzo[c]cinnoline 5,6‐dioxide. In a closed system, the reagents reduce both the nitro and olefin functional groups in 6‐nitro‐5,8‐dimethoxy‐1,4‐dihydro‐1,4‐ethano‐naphthalene. In an open flask flushed with argon, the reduction is confirmed to the nitro group. Reduction of 2‐chloro and 4‐chloronitrobenzene with palladium‐borohydride gives substantial yields of the appropriate chloroanilines. In contrast, hydrogen and palladium give aniline as the major product from each of these. These results suggest that the addition of sodium borohydride to palladium on carbon produces a reductive entity differing from that of catalytic hydrogenation.
Synthesis of multisulfur‐containing substituted dibenzothiophenes
Authors: Dunkerton L. V. , Barot B. C. , Nigam A.
Published: April 2009

New substituted dibenzothiophenes have been prepared and characterized. Selective functionalizations utilized substitutions of lithiodibenzothiophenes available from established methodology. New dibenzothiophenes prepared include 2‐(bromomethyl)dibenzothiophene (5), 2‐(thiomethyl)dibenzothiophene (6), 2‐S‐phenylthiomethyldibenzothiophene (24), 2‐S‐(2′‐dibenzothiophenylmethyl)thiomethyldibenzothiophene (25), 2‐S‐methyldibenzothiophene (30), 2‐S‐(p‐bromophenyl)dibenzothiophene (31), and 2‐S‐benzyldibenzothiophene (33). Dibenzothiophenes prepared from 4‐lithiodibenzothiophene include 4‐(bromomethyl)dibenzothiophene (13), 4‐(thiomethyl)dibenzothiophene (14), 4‐S‐(4′‐dibenzothiophenylmethyl)thiomethyldibenzothiophene (26), 4‐S‐(p‐tolyl)dibenzothiophene (34), 4‐S‐methyldibenzothiophene (35), 4‐S‐benzyldibenzothiophene (37), and 4‐S‐(p‐bromophenyl)dibenzothiophene (36). Similarly new 2,8‐disubstituted dibenzothiophenes prepared include 2,8‐bis(thiomethyl)dibenzothiophene (19), 2,8‐bis(S‐benzyl)dibenzothiophene (27), 2,8‐bis(S‐p‐tolyl)dibenzothiophene (28) and 2,8‐bis(S‐methyl)dibenzothiophene (29). The cmr chemical shift data for these dibenzothiophenes are also included.
Synthesis of a series of pyrrole‐1‐acetic acids as potential antiinflammatory agents
Authors: Ross John R. , Sowell J. Walter
Published: April 2009

A series of 3‐substituted 2‐amino‐4,5‐dimethylpyrrole‐1‐acetic acid derivatives were synthesized. The condensation of acetyl methyl carbinol, ethyl glycinate, and the appropriate acetonitrile yielded ethyl 3‐substituted 2‐amino‐4,5‐dimethylpyrrole‐1‐acetate, which was consequently hydrolyzed to produce the corresponding carboxylic acid. The acetamide and trifluoroacetamide series were synthesized by reacting the ethyl 2‐aminopyrrole‐1‐acetates with acetyl chloride or trifluoroacetic anhydride respectively. The corresponding 2‐acetamidopyrrole‐1‐acetic acids were formed by basic hydrolysis of the ethyl esters.
Reduction of α,β‐unsaturated nitroalkenes with borane and borohydrides. A convenient route to 3‐nitro‐, 3‐hydroxylamino‐, and 3‐amino‐2h‐1‐benzopyran derivatives
Authors: Varma Rajender S. , Gai Yuan‐Zhu , Kabalka George W.
Published: April 2009

The borohydride catalyzed borane reduction of 3‐nitrochromenes provided a facile route to a variety of 3‐hydroxylamino‐ 5 and 3‐amino‐2H‐1‐benzopyranes 6. Reduction with methoxyborohydride species, on the other hand, provided 3‐nitrochromans 2,4.
Non conventional syntheses of heterocyclic compounds. 3. Synthesis of indazole derivatives
Authors: Fusco Raffaello , Marchesini Alessandro , Sannicolò Franco
Published: April 2009

The thermal cyclization of a few 2,6‐dimethylphenylazo compounds to indazole derivatives is described.
Synthesis and reactions of halo‐, nitro‐, and arylazo‐substituted 3‐acetyltropolones. Formation of heterocycle‐fused troponoid compounds
Authors: Li Zhi‐Hong , Jin Zhong‐Tian , Yin Bing‐Zhu , Imafuku Kimiaki
Published: April 2009

3‐Acetyltropolone (1) reacted with bromine, iodine, and nitric acid to afford respectively 3‐acetyl‐5,7‐di‐bromotropolone (2), 3‐acetyl‐7‐iodotropolone (3), and 3‐acetyl‐5‐nitro‐ (4) and 3‐acetyl‐5,7‐dinitrotropolone (5). Azo‐coupling reactions of 1 gave 3‐acetyl‐5‐arylazotropolones 7a‐f. The Schmidt reactions of 2 and 3 gave respectively 5,7‐dibromo‐ (9) and 7‐iodo‐2‐methyl‐8H‐cyclohept[d]oxazol‐8‐one (10), while 4 gave 3‐acetamido‐5‐nitrotropolone (11). Compounds 2 and 4 reacted with hydroxylamine to give 3‐methyl‐8H‐cyclohept[d]isoxazol‐8‐ones 12 and 13. The reactions of 2, 3, and 4 with hydrazine gave 3‐methyl‐1,8‐dihydrocycloheptapyrazol‐8‐ones 15, 16, and 17.
Synthetic studies toward 4H‐1,3‐benzodioxin‐2‐ones
Authors: Podraza Kenneth F.
Published: April 2009

The investigation into the synthesis of 4H‐1,3‐benzodioxin‐2‐ones, utilizing the corresponding 2‐(hydroxy‐methyl)phenol as the starting diol, is described. The results illustrate that the synthesis of 4H‐1,3‐benzodi‐oxin‐2‐ones can be achieved utilizing carefully controlled reaction conditions, in a 3–15% yield.
Reaction of 4‐acylaminomethylpyridine N‐oxides with 5‐monosubstituted barbituric acids in presence of acetic anhydride
Authors: Braña M. F. , Castellano J. M. , Redondo M. C. , Yunta M. J. R.
Published: April 2009

The 5‐alkyl‐5‐[(3,5‐dimethylbenzoylamino)(4‐pyridyl)methyl]barbituric acids are obtained in the title reactions, but they fail when barbituric or 5‐phenylbarbituric acids are used. These results are explained by the pKa values of barbituric acids.
The gomberg‐bachmann reaction of purines
Authors: Mckenzie Thomas C. , Rolfes Steven M.
Published: April 2009

The reaction of adenine derivatives with isoamyl nitrite in anisole solution was re‐investigated. The arylated products are a mixture of ortho, meta, and para‐methoxyphenyl isomers with the ortho predominating. It is concluded that this is a typical free‐radical arylation and that the 6‐purinyl radical is a normal, well behaved aromatic radical.
Electron impact mass spectrometry of polyannulated oxygen heterocycles with cyclic orthoester or acetal moieties
Authors: Bravo Pierfrancesco , Ticozzi Calimero , Maccioni Anna Maria , Traldi Piero
Published: April 2009

The mass spectrometric behaviour of the pairs of diastereoisomeric 3‐methyl‐ and 3‐phenyl‐substituted 3,11b‐epoxy‐2,3,4,5,5a,11b‐hexahydro‐5a‐hydroxyoxepino[3,2‐c][1]benzopyran‐6‐ones 5,6 and 7,8 and the pairs of diastereoisomeric 3‐methyl and 3‐phenyl substituted 3,11a‐epoxy‐2,3,4,5,5a,11a‐hexahydro‐5a‐hydroxyoxepino[2,3‐b][1]benzopyran‐6‐ones 9,10 and 11,12 has been studied in detail with the aid of exact mass measurements, B/E linked scans, collisional experiments and deuterium labelling. Characteristic ionic species for angularly annulated compounds 5‐8 and for linearly annulated ones 9‐12 have been found, thus allowing the structural assignment. No differences could be determined in the fragmentation patterns of the diastereoisomeric compounds.