Synthesis of thiadiazoles,triazoles and oxadiazoles from sulfonyl acetic acids via a common route

A new class of five membered heterocycles, thiadiazoles, triazoles and oxadiazoles were prepared from sulfonyl acetic acids via acid hydrazides.     

Synthesis and some transformations of benzo[b]thiophene derivatives

A number of 3-chloro-2-chlorocarbonylbenzo [b] thiophenes with alkyl substituants in various positions of the benzene ring were synthesized by arylation of acrylic acid with the corresponding alkyl-substituted iodobenzenes under the influence of catalytic amounts of palladium acetate and subsequent oxidation of the resulting arylacrylic acids with thionyl chloride. Replacement of the pyridine added in the oxidation reaction by triethylbenzylammonium chloride led to substantial increases in the yields of the desired products. The possibility of conversion of the resulting benzo [b] thiophene derivatives to thiophene ring-unsubstituted benzo[b] thiophenes was shown in the case of 3-chloro-2-chlorocarbonylbenzo [b] thiophene as a result of successive saponification of the 2-chlorocarbonyl group, decarboxylation, and dechlorination.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1618–1622, December, 1982.     

K-region oxides and imines of benzo[b]phenanthro[2,3-d]thiophene and benzo[b]phenanthro[3,2-d]thiophene

The syntheses of the K-oxides and K-imine derivatives of benzo[b]phenanthro[2,3-d]thiophene and benzo-[b]phenanthro[3,2-d]thiophene are described. The parent hydrocarbons 1 and 2 were oxidized with osmium tetroxide and sodium metaperiodate, and the dialdehydes 12 and 18 so formed, cyclized to the corresponding epoxides 1a,12b-dihydrobenz[b]oxireno[9,10]phenanthro[2,3-d]thiophene ( 7 ) and 1a,12b-dihydrobenz-[b]oxireno[9,10]phenanthro[3,2-d]thiophene ( 13 ). Reaction of the oxiranes with sodium azide gave mixtures of azido-alcohols that, in turn, were transformed to the thiaarene imines 1a,12b-dihydro-1H-benz[b]azirino-[9,10]phenanthro[2,3-d]thiophene ( 8 ) and 1a,12b-dihydro-1H-benz[b]azirino[9,10]phenanthro[3,2-d]thiophene ( 14 ), respectively, with the aid of tri-n-butylphosphine.     

New reaction of benzo[b]thieno[3,2-b]benzo[b]thiophene disulfone

A new reaction of benzo[b]thieno[3,2-b]benzo[b]thiophene disulfone with amines that takes place with opening of one of the thiophene rings and nucleophilic substitution in the heteroaromatic ring at the site of cleavage of the S-C bond was observed. The molecular structures of the products of amination of the disulfone were determined by x-ray diffraction analysis. Hydrolysis and dehydration of the amination products gave derivatives of a new heterocyclic system, viz., benzo[b]-thieno[3,2-e]benzo[c]-1,2-oxathiin. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 320–323, March, 1980.     

Sulfur-rich heterocycles from 2-metalated benzo[b]thiophene and benzo[b]furan: synthesis and structure

The reaction of 2-lithiated benzo[b]thiophene with 8 equiv of elemental sulfur was found to give pentathiepino[6,7-b]benzo[d]thiophene. In contrast, treatment of 2-lithiated benzo[b]furan with sulfur under similar conditions produced the interesting ring system bis(benzo[4,5]furo)[2,3-e:3',2'-g][1,2,3,4]tetrathiocine. Both of these new cyclic polysulfides were studied by X-ray crystallography. Two polymorphic forms of pentathiepino[6,7-b]benzo[d]thiophene were found, displaying similar conformations but different packing schemes, which was also evident from powder diffraction data.     

1H NMR spectra of benzo[b]furan,benzo[b]thiophene and benzo[b]selenophene oriented in a lyotropic mesophase

The proton nuclear magnetic resonance spectra of benzo[b]-furan, -thiophene and -selenophene oriented in a potassium laurate lyotropic liquid crystal have been analyzed. Geometrical information has been obtained and compared to previous thermotropic results and various hypothetical models.     

Toluene dioxygenase-catalyzed cis-dihydroxylation of benzo[b]thiophenes and benzo[b]furans: synthesis of benzo[b]thiophene 2,3-oxide

Enzymatic cis-dihydroxylation of benzo[b]thiophene, benzo[b]furan and several methyl substituted derivatives was found to occur in both the carbocyclic and heterocyclic rings. Relative and absolute configurations and enantiopurities of the resulting dihydrodiols were determined. Hydrogenation of the alkene bond in carbocyclic cis-dihydrodiols and ring-opening epimerization/reduction reactions of heterocyclic cis/trans-dihydrodiols were also studied. The relatively stable heterocyclic dihydrodiols of benzo[b]thiophene and benzo[b]furan showed a strong preference for the trans configuration in aqueous solutions. The 2,3-dihydrodiol metabolite of benzo[b]thiophene was utilized as a precursor in the chemoenzymatic synthesis of the unstable arene oxide, benzo[b]thiophene 2,3-oxide.     

Synthesis of tetraorgano-substituted silanes with the benzo[b]thiophene moiety

Catalytic dehydrocyclization of dimethyl(o-tolyl)- and dimethyl-4-(m-xylyl)-(benzo[b]thien-2-yl) silanes has given 11,11-dimethyl and 8,11,11-trimethyl-6,11-dihydro-11-silabenzo[b]naphtho[2,3-d]thiophenes, which were oxidized to the ketones. Previously unknown diorganobis(benzo[b]thien-2-yl)silanes have been obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 419–422, March, 1989.     

Phenacylsulfonylacetic esters — source for thiadiazoles,triazoles and oxadiazoles

A new class of thiadiazoles, triazoles and oxadiazoles were prepared from phenacylsulfonylacetic ester by protecting the carbonyl group by oximation. Deoximation was affected by using β‐cyclodextrin in the presence of an oxidizing agent.     

2,2′‐Bi[benzo[b]thiophene]: an unexpected isolation of the benzo[b]thiophene dimer

The crystal structure of 2,2′‐bi[benzo[b]thiophene], C₁₆H₁₀S₂, at 173 K has triclinic (P) symmetry. It is of interest with respect to its apparent mode of synthesis, as it is a by‐product of a Stille cross‐coupling reaction in which it was not explictly detected by spectroscopic methods. It was upon crystal structure analysis of a specimen isolated from the mother liquor that this reaction was determined to give rise to the title compound, which is a dimer arising from the starting material. Two independent half‐molecules of this dimer comprise the asymmetric unit, and the full molecules are generated via inversion centers. Both molecules in the unit cell exhibit ring disorder, and they are essentially identical because of their rigidity and planarity.     

Synthesis of benzo[3,2]phenanthro[4,5-bcd]thiophene and chryseno[4,5-bcd]thiophene

Benzo[2,3]phenanthro[4,5-bcd]thiophene and chryseno[4,5-bcd]thiophene were synthesized, so that their mutagenic and carcinogenic activity can be determined.     

Synthesis of new 4-quinolone-type compounds in the benzo[b]thiophene series

Some new derivatives of 1,4-dihydro-4-oxo-3-pyridinecarboxylic acid (quinolone-type compounds) 5 and 13 have been prepared in the benzo[b]thiophene series. The key step was the construction of the pyridine ring starting from 2-aminobenzo[b]thiophene derivatives. The synthesis of amine 9 , was performed by using an original “animation” reaction.     

A facile synthesis of benzo[b]thiophene derivatives

Lithiation of S-(2-methylphenyl) N,N,N',N'-tetramethylphosphorodiamidothioate with sec-BuLi at -105° gave the corresponding benzylic anion which was acylated with various aromatic esters to give various deoxybenzoin derivatives in moderate to high yields. Acidic treatment of these products in refluxing formic acid gave 2-arylbenzo[b]thiophene derivatives. 2-Methylbenzo[b]thiophene and benzo[b]thiophen-2(3H)-one were also prepared using the similar procedure.     

Nucleophilic addition to benzo[b]thieno[2,3-b]benzo[b]thiophene S,S,S′,S′-tetroxide

The reaction of benzo[b]thieno[2,3-b]benzo[b]thiophene S,S,S′,S′-tetroxide with primary and secondary amines and with alcohols gave 10 b-amino- and 10 b-alkoxy-5a, 10b-dihydro-benzo[b]thieno[2,3-b]benzo[b]thiophene S,S,S′,S′-tetroxides. These nucleophilic reagents do not add to benzo[b]thieno[2,3-b]benzo[b]thiophene S,S-dioxide.     

Synthesis of benzo[4,5]phenaleno[1,9-bc]thiophene and benzo[4,5]phenaleno[9,1–6c]thiophene

Two pentacyclic thiophenes, benzo[4,5]phenaleno[1,9–6c]thiophene ( 1 ) and benzo[4,5]phenaleno[9,1-bc]-thiophene (2) were synthesized via the corresponding 3-methylphenanthro[2,1-b]thiophene (7) and 1-methylanthra[2,1–6]thiphene ( 19 ).     

1H NMR spectra of the 2-trifluoroacetyl derivatives of benzo[b]furan and benzo[b]thiophene

The ¹H NMR spectra of the 2-trifluoroacetyl derivatives of benzo[b]furan and benzo[b]thiophene were recorded at 200MHz in two solvents, chloroform and acetone. A long-range coupling constant, 5J(HF), between the fluorine nuclei of the trifluoroacetyl group and H-3, of a value higher than 1 Hz, was measured. From the comparison of the ¹H chemical shifts of, and the solvent effects on, the trifluoroacetyl compounds and those of the corresponding 2-acetyl derivatives, and on the basis of an empirical interpretation of the ⁵J(HF) coupling constant, a predominant Z conformation was tentatively assigned to these derivatives.     

Synthesis of new type benzo[b]thiophene fused quinones and their tetracyanoquinodimethane derivatives

A series of new type of benzo[b]thiophene-fused 1,4-benzoquinones and their tetracyanoquinodimethane derivatives were synthesized. The cyclic voltammetric data of new type quinones and tetracyanoquinodimethane derivatives displayed different behavior. All new quinones exhibit two reduction waves corresponding to the radical anion and dianion. On the other hand, most tetracyanoquinodimethane derivatives display a singlewave reduction to the dianion. The benzo[b]thiophene moiety fused tetracyanoquinodimethane derivatives reveal more negative reduction potentials than that of tetracyanoquinodimethane.