The mass spectra of some 1H-imidazo[1,2-a]pyrrolo[3,2-e]pyridines

We report here the mass spectral fragmentations of some derivatives of a new heterocyclic system 1H-imidazo[1,2-a]pyrrolo[3,2-e]pyridine. These compounds combine structural features of 1H-pyrrolo[2,3-b]pyridines and imidazo[1,2-a]pyridines, but follow fragmentation pathways similar to the former.     

A 13C-NMR assignment study of a series of 2,3,4,5-tetrahydro-1-methyl-1H-1,5-benzodiazepine-2,4-diones

The natural abundance ¹³C-nmr spectra of a series of 2,3,4,5-tetrahydro-1-methyl-1H-1,5-benzodiazepine-2,4-diones have been recorded: two of these compounds, clobazam and triflubazam, are clinically used as psychotherapeutic agents. The assignments of the various resonances have been made by chemical shift arguments, by the analysis of the fine splittings caused by one bond and long range couplings, and also by comparison with model compounds.     

Synthesis of some novel fused tetracyclic quinolonecarboxylic acids via 7-methyl-6,7,8,9-tetrahydro-3H-imidazo[4,5-f]quinoline and 6-methyl-5,6,7,8-tetrahydro-1H-imidazo[4,5-g]quinoline

A series of fused tetracyclic quinolonecarboxylic acids was prepared for biological evaluation. These compounds were synthesized by a route involving a regiospecific functionalization of 5-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline to obtain a series of new substituted 7-methyl-6,7,8,9-tetrahydro-3H-imidazo[4,5-f]quinolines and 6-methyl-5,6,7,8-tetrahydro-1H-imidazo[4,5-g]quinolines as convenient precursors of quinolones.     

Synthesis of 5H-5-oxobenzimidazo[2,1-b]pyrido[3,2-e][1,3]thiazine,A novel ring system

Reaction between 2-chloronicotinic acid chloride and 2-mercaptobenzimidazole afforded 5H-5-oxobenzimidazo[2,1-b]pyrido[3,2-e][1,3]thiazine, a novel heterocyclic ring system. The assigned structure was confirmed by means of mass spectrometry.     

Synthesis of 3,4-Dihydro-2-methyl-3-oxo-N-aryl-2H-[1]benzothieno[3,2-e1,2-thiazine-4-carboxamide 1,1-Dioxides

A novel synthesis of the title compounds, representing a new heterocyclic ring system, is described. Chlorosulphonation of 3-methylbenzo[b]thiophene followed by reaction with methylamine gave sulfonamide, 4 . Lithiation of 4 , followed by quenching with carbon dioxide yielded acetic acid, 5 . Cyclodehydration of 5 to benzothienothiazine 6 followed by reaction with aryl isocyanates afforded the desired benzothieno[3,2-e]-1,2-thiazine-4-carboxamides 1a-f.     

Synthesis and molecular structure of 1,4-dimethyl-4,5,7,8-tetrahydro-6H-imidazo[4,5-e][1,4]-diazepine-5,8-dithione

1,4-dimethyl-4,5,7,8-tetrahydro-6H-imidazo[4,5-e][1,4]-diazepine-5,8-dithione was synthesized by boiling 1,4-dimethyl-4,5,7,8-tetrahydro-6H-imidazo[4,5-e][1,4]-diazepine-5,8-dione (a cyclic homolog of theobromine) with P₂S₅. Its molecular and crystal structures were determined by X-ray structure analysis, PMR spectroscopy and the calculations using the MM2 program. The crystals are monoclinic, sp. gr. P2 ₁ /n with a=9.305(4), b=9.464(3), c=11.628(3) Å, -90.49(3)^o, Z=4 for C₈H₁₀N₄S₂. M.p. 268–269 °C. The 7-membered heterocycle has a boat conformation in the crystal, while in solution at room temperature it undergoes interconversion. The geometrical parameters of the molecule obtained by X-ray structure analysis, by PMR spectroscopy below the coalescence temperature (290 K), and by MM2 calculations are in good agreement.A. V. Bogatsky Physico-Chemical Institute, Ukrainian Academy of Sciences. Translated fromZhurnal Struktumoi Khimii, Vol. 34, No. 3, pp. 86–90, May–June 1993.Translated by T. Yudanova.     

New [g]-fused [1,2,4]triazolo[1,5-c]pyrimidines: Synthesis of pyrido[3,2-e] and [4,3-e][1,2,4]triazolo[1,5-c]pyrimidine,pyrimido[5,4-e][1,2,4]triazolo[1,5-c]pyrimidine and [1,2,4]triazolo[1,5-c]pteridine derivatives

A number of 2-aryl-substituted pyrido[3,2-e] and [4,3-e][1,2,4]triazolo[1,5-c]pyrimidines and [1,2,4]triazolo[1,5-c]pteridines 11,12a,b,e , their corresponding 5-carbonyl derivatives 7,8a,b,e and some pyrimido[5,4-e][1,2,4]triazolo[1,5-c]pyrimidin-5-ones 7,8c,d have been synthesized, according to different pathways. The new tricyclic heterocycles were prepared with the aim of studying their possible benzodiazepine receptors affinity.     

Synthesis of 9-methyl-1H-[1,4]thiazino[3,2-g]quinoline-2,5,10(3H)-trione, the B,C,D ring core of the shermilamine alkaloids

Synthesis of 9-methyl-1H-[1,4]thiazino[3,2-g]quinoline-2,5,10(3H)-trione (4), from N-(4-bromo-2,5-dimethoxyphenyl)acetamide (23) is described. Oxidative cyclisation of 2,2'-disulfanediylbis[N-(2,5-dimethoxyphenyl)acetamide] (19) to 5,8-dimethoxy-2H-1,4-benzothiazin-3(4H)-one (7b) is also reported.     

Synthesis of nitro-substituted 4-methyl-2,3-dihydro- and 2,3,4,5-tetrahydro-1H-1,5-benzo-2-diazepinones

The nitration of 4-methyl-2,3-dihydro-1H-1,5-benzo-2-diazepinone gives the 7 nitro derivative. The 8-nitro isomer was obtained from 4-nitro-1,2-phenylenediamine. The catalytic hydrogenation of the nitrobenzodiazepinones gives the 7- and 8-amino derivatives. The nitrobenzodiazepinones exist in the enol form in alkaline media.     

Synthesis of derivatives of a new heterocyclic system, 9-oxo-1,3,4-thiadiazolo[3,2-a]pyrido[3,2-e]pyrimidine

Reaction of 2-substituted 5-imino-7-oxo-1,3,4-thiadiazolo[3,2-a]pyrimidines with pentane-2,4-dione in polyphosphoric acid yields 9-oxo-1,3,4-thiadiazolo[3,2-a]pyrido[3,2-e]pyrimidines.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2037–2038, October, 1995.The authors are grateful to V. A. Dorokhov for the skilled preparation of the paper for publication.     

1, 3-dipolar cycloaddition of diazomethane to azolopyridazines. The synthesis of 8-methyl-8H- and 9-methyl-9H-pyrazolo[3, 4-d]-s-triazolo[4, 3-b]pyridazine and 1-methyl-1H- and 2-methyl-2H-imidazo[1, 2-b]pyrazolo[3, 4-b]pyridazine derivatives

The transformations of 7-methyl-7H- and 8-methyl-8H-pyrazolo[4, 3-d]tetrazolo[1, 5-b]pyridazines 1, 2, 9 and 10 into 8-methyl-8H- and 9-methyl-9H-pyrazolo[3, 4-H]-s-triazolo[4, 3-b]pyridazines 7 and 8 , and 1-methyl-1H-and 2-methyl-2H-imidazo[1, 2-b]pyrazolo[3, 4-d]pyridazines 13 and 14 are described.     

Structural assignment of 2,3,7,8-tetrahydro-5H,10H-[1,5,3]dioxazepino[3,2-c]indolo[3,2-g]pteridin-7-one,a New heterocyclic ring system

The structure of a new heterocyclic ring system, 2,3,7,8-tetrahydro-5H,10H-[1,5,3]dioxazepino[3,2-c]-indolo[3,2-g]pteridin-7-one, derived from isatins and 5-aminocytidine was assigned by establishing the regiochemistry with the aid of model reactions and ¹³C nmr techniques.     

1H-, 31P- and 13C-NMR spectra of some 2-arylsulphonylamido-2-thiono-5-methyl-1,3,2-dioxaphospholanes

Some 2-arylsulphonylamido-2-thiono-5-methyl-1,3,2-dioxaphospholanes (1), containing two chiral centres, give NMR spectra in which splittings of the ¹H and ¹³C signals of the 5-methyl substituent and of the ³¹P signal indicate that they exist in an approximately 70:30% ratio of two racemic mixtures, Z and E respectively, diastereomeric to each other. These splittings were invariably observed for compounds 1a, containing a monosubstituted sulphonylamido group (Y = H) and various substituents at position 4′ of the aryl group, X = H, CH₃, OCH₃, F, CI and Br. The methylenic protons in position 4 of the phospholane ring are diastereotopic and therefore magnetically non-equivalent. Benzene-induced shifts were measured for the Z isomers of compounds 1a, X = H, F and for compound 1b, containing an N-disubstituted sulphonylamido group (Y = CH₃) and X = H; the tentative interpretation of these shifts places the more shielded diastereotopic methylene proton on the same side of the ring as the 5-methyl substituent. The H? P and H? H coupling constants indicate that the preferred conformation of the dioxaphospholane ring should be a ‘twisted envelopey’ shape with the 5-methyl substituent in the equatorial position.     

Synthesis of 10-(4-methyl-1-piperazinyl)thieno[3,2-b][1,5]benzothiazepines

A series of the title compounds has been synthesized by two alternative methods in order to study their potential neuroleptical activity and to compare it with the pharmacological data already obtained for compounds of other isomeric or related series.     

Synthesis of 10-(4-methyl-1-piperazinyl)thieno[3,2-b][1,5]benzoxazepines

A series of the title compounds has been synthesized starting from methyl 3-hydroxythiophene-2-carboxylate. Its condensation with 2,4-dinitrochlorobenzene provides through compound 4e a way to introduce 7-substituents by means of diazonium salts reactions.     

Synthesis of 3-methyl-2,3,4,4a,5,6-hexahydro-1H-benzofuro[3,2-e]isoquinoline-7(7aH)-ones

The 2,3,4,4a,5,6-hexahydro-1H-benzofuro[3,2-e]isoquinoline-7(7aH)-one ring system is prepared from a 4-arylpyridine precursor by sequentil intramolecular enolate addition to a pyridinium ion, Dieckmann cyclization, and catalytic hydrogenation.     

Synthesis of 1-aryl-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indoles (1,2,3,4-tetrahydro-β-carbolines) under high pressures

The reactions of aromatic aldehydes with tryptamine (1) in solvents of different polarity were studied. The yields of carbolines in the chosen media decrease with an increase in the donating properties of the aryl substituent, but they markedly increase at a high pressure (5 kbar), especially for compounds with electron-donating aryl groups. The phase transition of dioxane at 5 kbar also sharply increases the yields of the target products.     

Synthesis of 4,10-dihydro-4,10-dioxo-1H-[1]-benzopyrano[3,2-b]pyridine, 4,5-Dihydro-4,5-dioxo-1H-[1]-benzopyrano[2,3–6]pyridine and 1,5-Dihydro-1,5-dioxo-4H-[1]-benzopyrano[3,4-b]pyridine derivatives from aminobenzopyrones

3-Aminochromone and 3-aminocoumarin were condensed with diethyl ethoxymethylenemalonate and with dimethyl acetylenedicarboxylate to give intermediates, which were thermally cyclized to give 4,10-dihydro-4,10-dioxo-lH-[1]-benzopyrano[3,2-b]pyridinecarboxylates and 1,5-dihydro-1,5-dioxo-4H-[1]-benzopyrano-[3,4-b]pyridinecarboxylates. 2-Aminochromone was converted to 4,5-dihydro-4,5-dioxo-1H-[1]-benzopyrano-[2,3-b]pyridinecarboxylate via an intermediate condensation product with diethyl ethoxymethylenemalonate. These esters were hydrolyzed to the corresponding carboxylic acids (21, 30, 36, 50, and 60). Attempts to prepare 4,5-dihydro-4,5-dioxo-1H-[1]-benzopyrano[4,3-b]pyridinecarboxylates from 4-aminocoumarin were unsuccessful.