Pyrazino[2,3-c][1,2,6]thiadiazine 2,2-dioxides. Sulfur dioxide analogs of pteridines

Several pyrazino[2,3-c][1,2,6]thiadiazine 2,2-dioxide derivatives have been synthesized for the first time by condensation of suitable 4,5-diamino-1,2,6-thiadiazine 1,1-dioxides and symmetrical 1,2-dicarbonyl compounds. Structures of these compounds have been characterized by their elementary analyses, ¹H-nmr and uv spectra as well as their pK_a values. The most striking differences between this series and the corresponding pteridines are discussed.     

Synthese von 5,6-Dimethyl-4-oxo-1,3,4,5-tetrahydro-imidazo-[4,5-c] [1,2,6]thiadiazin-2,2-dioxid und 7-Methyl-4-oxo-1H-3,4-dihydro-pyrimido[4,5-c][1,2,6]thiadiazin-2,2-dioxid

Synthesis of 5,6-Dimethyl-4-oxo-1,3,4,5-tetrahydro-imidazo[4,5-c][1,2,6]thiadiazin 2,2-dioxide and 7-Methyl-4-oxo-1H-3,4-dihydropyrimido[4,5-c][1,2,6]thiadiazin 2,2-dioxide The derivatives of the above heterocyclic ring systems were prepared by reaction of the corresponding o-amino esters with sulfamoylchloride.     

Synthesis of 7-amirio-2H, 4H-vic-triazolo[4,5-c]-[1,2,6]thiadiazine 5,5-dioxides

7-Amino-2H,4H-vic-triazolo[4,5-c][1,2,6]thiadiazine 5,5-dioxide was prepared by two different ways from 3,4,5-triamirio-1,2,6-lhiadiazine 1, 1-dioxide and 3,5-diamino-4H-1,2,6-thia-diazine 1, 1-dioxide respectively. 7-A:nino-2-phenyl-4H-vic-triazolo[4,5-c] [1,2,6]thiadiazine 5,5-dioxide was obtained by lead telraacetate oxidation of 3,5-diamino-4-phenylazo-1, 2, 6-thiadiazine 1, 1-dioxide.     

Synthesis of substituted pyrrolo[2,3-e][1,3,4]thiadiazine 4,4-dioxides

A series of substituted pyrrolo[2,3-e][1,3,4]thiadiazine 4,4-dioxides is synthesized from 1-substituted-2-amino-3-cyanomethylsulfonyl-4,5-dimethylpyrroles.     

Reactivity of 4-amino-6,7-diphenyl-8H-pyrazino[2,3-c]-1,2,6-thiadiazine 2,2-dioxide towards methylating agents

Reaction of the title compound with different methylating agents to give mono-, di- and trisubstituted derivatives has been studied.     

Nitration studies of naphtho[2,3-c][1,2,5]thiadiazole

Nitration of naphtho[2,3-c][1,2,5]thiadiazole gives the 5-nitro derivative in 61–66% yield. Chlorination of this product apparently gives an unstable addition product which loses hydrogen chloride on recrystallization to give 4-chloro-8-nitronaphtho[2,3-c][1,2,5]thiadiazole. Thus, naphtho[2,3-c][1,2,5]thiadiazole under nitrating conditions behaves as a 2-substituted naphthalene rather than as an anthracene analog.     

Pyrido[2,3-g]quinolines

The heretofore unknown sym-octahydro-4,9-dioxopyrido[2,3-g]quinoline was synthesized by carboxyethylation of dimethyl 2,5-diaminoterephthalate with -propiolactone with subsequent hydrolysis of the resulting 2,5-bis(-carboxyethylamino)terephthalic acid ester and cyclization of 2,5-bis(-carboxyethylamino)terephthalic acid. The structure of the product was confirmed by the UV and IR spectra and also by reduction to the known sym-octahydropyrido [2,3-g]quinoline.See [7] for preliminary communication.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1535–1537, November, 1970.     

The synthesis of [1]benzothieno[2,3-c]quinolines, [1]benzothieno[2,3-c][1,2,4]triazolo[4,3-a]quinoline,and [1]benzothieno[2,3-c]tetrazolo[1,5-a]quinoline

Photocyclization of 3-chloro-N-phenylbenzo[b]thiophene-2-carboxamide 10 afforded [1]benzothieno[2,3-c]-quinolin-6(5H)-one 11 which was chlorinated to 6-chloro[1]benzothieno[2,3-c]quinoline 12 followed by dechlorination to give [1]benzothieno[2,3-c]quinoline 5 . A series of 6-substituted alkoxy and thioalkoxy[1]benzothieno[2,3-c]quinoline derivatives were prepared along with the N-methyl quaternary salt 13 of 5 . 6-Chloro[1]-benzothieno[2,3-c]quinoline 12 was converted into 6-hydrazino[1]benzothieno[2,3-c]quinoline 23 which upon treatment with formic acid yielded [1]benzothieno[2,3-c][1,2,4]triazolo[4,3-a]quinoline 6 . Treatment of 23 with nitrous acid resulted in [1]benzothieno[2,3-c]tetrazolo[1,5-a]quinoline 7 . Compounds 6 and 7 are novel heterocyclic ring systems.     

Reactions of Cyanomethanesulfonamides with Aldehydes and Synthesis of 2-Benzyl-2,3-dihydrobenzopyrano[3,2-e] [1,2,4]thiadiazine 1,1-Dioxides

Summary.  Reactions of cyanomethanesulfonamides with aromatic aldehydes in the presence of AcOH and piperidine produced the addition products, the 1-cyano-2-arylethenesulfonamides, whereas reactions with benzonitrile yielded the 2-amino-1-cyano-2-phenylethenesulfonamides only when done in THF with BuLi. No addition products were isolated from the analogue reactions with 2-hydroxybenzaldehyde (salicylaldehyde). Instead, we obtained 2-imino-2H-chromene-3-sulfonamides with good to excellent yields. These 2H-chromene derivatives allowed a number of transformations, from which the reactions with orthoformates opened an approach to the hitherto unknown benzopyrano[3,2-e] [1,2,4]thiadiazine ring system.     

Reactions of Cyanomethanesulfonamides with Aldehydes and Synthesis of 2-Benzyl-2,3-dihydrobenzopyrano[3,2-e] [1,2,4]thiadiazine 1,1-Dioxides

Reactions of cyanomethanesulfonamides with aromatic aldehydes in the presence of AcOH and piperidine produced the addition products, the 1-cyano-2-arylethenesulfonamides, whereas reactions with benzonitrile yielded the 2-amino-1-cyano-2-phenylethenesulfonamides only when done in THF with BuLi. No addition products were isolated from the analogue reactions with 2-hydroxybenzaldehyde (salicylaldehyde). Instead, we obtained 2-imino-2H-chromene-3-sulfonamides with good to excellent yields. These 2H-chromene derivatives allowed a number of transformations, from which the reactions with orthoformates opened an approach to the hitherto unknown benzopyrano[3,2-e] [1,2,4]thiadiazine ring system.     

A novel crystalline tetrazolo-azido isomer pair: Pyrido[ 2,3-e] tetrazolo[5,1-c]-as-triazine and 3-azidopyrido[2,3-e]-as-triazine; the synthesis of tetrazolo[5,1-c] benzo-as-triazine and pyrido[2,3-e]-s-triazolo[3,4-c] -as-triazine

The deoxygenated derivative of 3-azidobenzo-as-triazine 1-oxide (II) exists in solution predominantly as 3-azidobenzo-as-triazine form (IVa) but in the crystalline state as tetrazolo[5,]-c]-benzo-as-triazine (IVb), a new fused heteroaromatie ring system. With the pyrido[2,3-e]-as-triazine derivatives, however, both 3-azidopyrido[2,3-e]-as-triazine (X) and pyrido[2,3-e] tetra-zolo[5,1-e]-as-triazine (XI) can be isolated in crystalline form, and these are interconvertible. Another new ring system, the pyrido[2,3-e] triazolo [3,4-c]-as-triazine (XVII) and its derivatives has also been synthesized.     

The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 2 . Benzo[h][1]benzothieno[2,3-c]quinoline and benzo[h][1]benzothieno[2,3-c]quinoline

The synthesis of two previously unknown unsubstituted heterocyclic ring systems namely, benzo[h][1]benzothieno[2,3-c]quinoline ( 6 ) and benzo[f][1]benzothieno[2,3-c]quinoline ( 12 ) is reported. These two novel ring systems have been assembled by photocyclization of the appropriate amides.     

Furopyridines. II. Bromination and nitration of furo[2,3-b]-, furo[3,2-b]-, furo[2,3-c]- and furo[3,2-c]pyridine

In order to reveal the reactivities of furopyridines, we undertook bromination and nitration of four furopyridines ( 1, 2, 3 and 4 ) whose chemical properties had been almost unknown. Bromination of 1, 2, 3 and 4 gave the corresponding trans-2,3-dibromo-2,3-dihydro derivatives 6, 8, 10 and 12 , respectively, which were converted to 3-bromofuropyridines 7, 9, 11 and 13 by treatment with sodium hydroxide in aqueous methanol. Nitration of 1 with a mixture of fuming nitric acid and sulfuric acid afforded a mixture of addition products 14a, 14b and 14c and 2-nitro derivative 15 . Both 14a and 14b were easily converted to 15 by treatment with sodium bicarbonate. Compound 2 was nitrated to give a mixture of cis- and trans-2-nitro-3-hydroxy-2,3-dihydro derivative 16a and 16b and 2-nitro derivative 17 . The cis isomer 16a was transformed to the trans isomer 16b by refluxing on silica gel in ethyl acetate. Compound 16b was dehydrated with acetic anhydride to give 17 . Nitration of 3 gave a nitrolic acid derivative 20 . Nitration of 4 gave a mixture of 2-nitro derivative 22 and 3-(trinitromethyl)pyridin-4-ol ( 23 ). The structures of 20 and 23 were established by single crystal X-ray analysis. The differences of behavior observed in these reactions are discussed in connection with the results of the determination of pKa values and the relative reactivities of deuteriodeprotonation of these furopyridines.     

A new synthesis of 2,3-dihydrofuro[2,3-b], [2,3-c] and [3,2-c]quinolines

A new synthesis of three isomeric dihydrofuroquinolines is described. This route via ortholithiation of O-quinolyl carbamates is considerably more effective than that which proceeds via lithiation of alkoxyquinolines.     

Facile synthesis of novel [1,3]oxazino[2,3-c][1,2,4] thiadiazin-12-one derivatives

Several novel fused heterocyclic systems which have rings containing N/O or N/S have been synthesized through a facile one-pot method by the treatment of substituted 2-(benzo[d]thiazol-2-yl)phenol and cyanogen bromide in THF and NEt₃. This one-pot method contains tough ring-opening of thiazole, special intermolecular rearrangement and ring-closing reactions. The newly synthesized compounds were characterized by HR-MS, ¹H-NMR, ¹³C-NMR spectral data and DFT calculation analysis. 2a was also determined by X-ray crystallographic analysis.     

A Convenient Synthesis of NovelDerivatives of Pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidine-5,6-dione

Summary.  Reaction of 6-Amino-2-thiouracil with hydrazonoyl halides yielded regioselectively 7-amino-1,3-disubstituted-1,2,4-triazolo[4,3-a]pyrimidine derivatives. Upon treatment with methyl (Z)-2-benzoylamino-3-dimethylaminopropenoate, the corresponding methyl (Z)-2-benzoylamino-3-([1,2, 4]triazolo[4,3-a]pyrimidin-7-yl)-amino propenoates were obtained which cyclized in the presence of sodium ethoxide to afford novel derivatives of pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidine-5,6-(1H,8H)-diones. E-mail: mosselhi@chem-sci.cairo.eun.eg Received February 8, 2002; accepted (revised) March 18, 2002     

1,2,4-Triazino[4,3-c]- and [2,3-c]quinazolines

This paper describes the reactions of 2-o-aminophenyl-1,4,5,6-tetrahydro-1-methyl-1,2,4-triazine with a variety of reagents to give substituted 1,2,4-triazino[4,3-c]quinazolines or 1,2,4-triazino[2,3-c]quinazolines. Certain representative compounds of these two new heterocyclic systems were characterized by the tlc, ir, nmr, mass spectra, and identified by unequivacol synthesis.