1,3,4,6-Tetrakis(isopropylthio)thieno[3,4-c]thiophenium bis(tetrafluoroborate): X-ray crystal structure of a stable thieno[3,4-c]thiophene dication

The structure of the 1,3,4,6-tetrakis(isopropylthio)thieno[3,4-c]thiophene dication ( 2 ) prepared from 1,3,4,6-tetrakis(isopropylthio)thieno[3,4-c]thiophene ( 1 ) by two-electron oxidation was investigated by X-ray crystallographic analysis. The results revealed that the positive charges are largely delocalized on the two i-PrS-C-C-C-SPr-i moieties.     

Tetrakis(alkylthio)thieno[3,4-c]thiophene: Synthesis,stability, and reactivity

The synthesis of tetrakis(alkylthio)thieno[3,4-c]thiophenes la-e by the dimerization reaction of bis(alkylthio)cyclopropenethiones is described. The remarkable thermodynamic and kinetic stability suggests the significant electron-accepting conjugation of the alkylthio substituents to the carbanionic 1, 3, 4, and 6 carbons in the framework. The isopropylthio- and ethylthio-substituted thienothiophenes 1d and 1e undergo cycloaddition reactions with dienophiles such as N-phenylmaleimide and dimethyl acetylenedicarboxylate to give the cycloadducts in moderate yields.     

Oxidation of 1,3,4,6-tetrakis(alkylthio)thieno[3,4-c]-thiophenes with iodine in the presence of aniline

1,3,4,6-Tetrakis(alkylthio)thieno[3,4-c]thiophenes were oxidized by iodine in the presence of aniline in dry benzene to give 1,4,6-tris(alkylthio)thieno[3,4-c]thiophen-3(1H)-imines in high yields through the intermediary formation of their cation radicals.     

Synthesis of thieno[3,4-c] and thieno[3,2-c][2,1]benzothiazepines

Starting from [4,3-c] and [3,2-c] methyl chlorosulfonylthiophenecarboxylates the synthesis of ketones 7 and 8 is described. These compounds are the first two representatives of the new thieno[3,4-c] and thieno-[3,2-c][2,1]benzothiazepine ring systems. The formation of methyl 3-chlorosulfonylthiophene-2-carboxy-late is also revised.     

Synthesis of thieno [3,4-c ]- and selenopheno[3,4-c] pyrylium salts

Acylation of 3-acetonyl- and 3-phenacyl-2,5-dimethylthiophenes with aliphatic acid anhydrides in the presence of perchloric acid gives thieno[3,4-c]pyrylium perchlorates. Reaction of the latter with ammonia gives the corresponding thieno[3,4-c]pyridines or diketones of the thiophene series. Selenopheno[3,4-c]pyrylium salts could not be isolated in the acylation of 3-acetonyl- and 3-phenacyl-2,5-dimethylselenophenes.     

The synthesis and chemical reactivity of thieno[2,3-c]- and thieno[3,2-c] pyridines

The syntheses and reactions of various thieno[2,3-c]- and thieno[3,2-c] pyridines are described. Molecular orbital calculations were performed on thieno[2,3-c]pyridine (1) in order to determine the most susceptible sites to electrophilic and nucleophilic attack. Superdelocalizability values, S_r- are reported for each position in this molecule to give relative orders of reactivity towards the two types of reactions. Electrophilic attack was found to occur experimentally at C-3 in all the thienopyridines studied. Peracid oxidation of thieno[2,3-c]- and thieno[3,2-c]pyridines produced only the N-oxide. The lack of reactivity of certain thienopyridines under Vilsmeier formylation and Friedel-Crafts acetylation conditions was related to their basicities. The dissociation constants of various thienopyridinium salts are reported.     

Chemistry of thienopyridines. XV. Syntheses of thieno [3,4-b] - and thieno[3,4-c] pyridines

Thieno [3,4-b] pyridine (5) was synthesized by means of the successive steps of (a) photochlorination of 2,3-dimethylpyridine to the bis(chloromethyl) compound, (b) condensation with sodium sulfide, (c) oxidation to the sulfoxide, and (d) catalytic dehydration by means of alumina. Thieno[3,4-c]pyridine (6) was obtained in an analogous manner. Spectral properties indicate that 5 and 6 have aromatic character.     

Directed synthesis of alkyl-substitued pyrrolo[3,4-c]pyrrole-1,3,4,6-tetraones

Reactions of 3-amino-8-hydroxy-1,6-dioxo-2,7-diazaspiro[4.4]non-3-ene-4-carbonitriles with aqueous hydrohalic acid led to the formation of alkyl-substituted pyrrolo[3,4-c]-pyrrole-1,3,4,6-tetraones.     

Synthesis of 1H-thieno[3,4-c]pyrazoles,thieno[3,4-b]furans,selenolo[3,4-b]furans and pyrrolo[3,4-d]thiazoles

Starting from the readily available aryl 2-methyl-5-phenyl-3-furyl ketones, 5-methyl-1H-1-phenylpyrazole-4-yl ketones and 4-methyl-2-phenyl-5-thiazolylcarboxaldehyde, a series of 2-phenyl-4-arylthieno[3,4-b]-furan, 2-phenyl-4-(p-methoxyphenyl)selenolo[3,4-b]furan, 4-aryl-1H-1-phenylthieno[3,4-c]pyrazole and 5-benzyl-2-phenylpyrrolo[3,4-d]thiazole were prepared in high yield.     

Preparation of reissert compounds derived from the thieno[3,2-c]pyridine,thieno[2,3-d]pyridazine and the thieno[2,3-d]pyrimidine ring systems

The use of tributyltin cyanide, trimethylsilyl cyanide and potassium cyanide in the Reissert reaction is contrasted in the furo[3,2-c]pyridine, thieno[3,2-c]pyridine, thieno[2,3-dpyridazine, and thieno[2,3-d]pyrimidine ring systems.     

Polymethyl derivatives of furo[3,4-c]pyran4-one,furo[3,4-c] pyridin-4-one and pyrrolo[3,4-c]pyran-4-one

The: title compounds were prepared from Michael adducts, obtained from acetoacetic esters and trans-3-hexene-2,5-dione, and from the corresponding dehydration products, by direct cyclization to oxygen rings or by reaction with ammonia (or methylamine) to give nitrogen rings.     

Synthesis and structure of 3-oxopyrano[3,4-c]pyridines

Acylation of the enamine of 2,2-dimethyltetrahydropyran-4-one with acid chlorides produced -acylpyran-4-ones which give 3-oxopyrano[3,4-c]pyridines when treated with cyanoacetamide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1137–1142, August, 1989.     

Preparation and regiochemical assignments of new pyrazolo[3,4-c] [2,1]benzodiazepines

The preparation of new pyrazolo[3,4-c][2,1]benzothiazepines substituted at the nitrogen atoms of the pyrazole moiety is described. It was carried out by reaction of the 4,9-dihydro-9-methyl-4,10,10-trioxo-1(2)H-pyrazolo[3,4-c][2,1]benzothiazepine ( 1 ) with several alkylating agents under both classical and phase-transfer catalysis (PTC) conditions. Assignments of the N-alkyl regioisomers obtained were performed by study of their ¹H nmr spectra and NOE experiments.     

Synthesis of 1-(hydroxyaryl)furo[3,4-c]pyridines from 1-amino(alkoxy)furo[3,4-c]pyridines and (poly)phenols

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Selenium heterocycles. XXXIII. Synthesis of thieno[3,4-b]furan,seleno[3,4-b]furan,thieno[3,4-b]indole and seleno[3,4-b]indole. four novel heterocycles

Starting from the readily available 2-methyl-3-benzoylfuran, 1-phenylthieno[3,4-b]furan and 1-phenyl-seleno[3,4-b]furan were prepared. Also, starting from phenyl 3-methylindol-2-yl ketone and aryl 2-methyl-indole-3-yl ketones a series of substituted thieno[3,4-b]indoles and substituted seleno[3,4-b]indoles were prepared.