Thiophene 1,1-dioxides 2,3-dihydro

Thiophen Dioxides and their Dihydro and Tetrahvdro Derivatives. - Flash vacuum pyrolysis of cobalt complexes (194) of thiophen 1 1-dioxides led to extrusion of sulphur dioxide and the formation of cyclobutadiene complexes (195). Stereochemical labelling experiments were employed in order to determine the mechanism of this transformation.114 A detailed publication on the reaction of... 

The synthetic utility of o-quinodimethane generated by cheletropic elimination of S02 has been amply demonstrated by Oppolzer and Nicolaou, who have conducted an intramolecular cycloaddition coupled with the alkylation of 1,3-dihydrobenzo[c]thiophene 2,2-dioxide122. When 1,3-dihydro-l-(4-pentenyl)benzo[c]thiophene 2,2-dioxide (201) prepared from 1,3-dihydrobenzo[c]thiophene 2,2-dioxide and 4-pentenyl bromide is heated in di-n-butyl... 

Tetrahydro-thiophen-l,l-dioxidc werden als Anionen von Lithiumalanat unter Ringverengung zu Cyclo-butenen reduziert3. 3,4-Dihydro-thiophen-1,1 -dioxide liefern dagegen offenkettige Diene4. 

Sato and coworkers reported recently an interesting oxidation reaction of 1,4-dihydro-l,4-diphenyl-2,3-benzodithiin . When compound 38 was treated with m-CPBA in CH2CI2, ring contraction to l,3-diphenylbenzo[c]thiophene 39 was observed. With H2O2 in CH3COOH, the reaction afforded l,3-dihydro-l,3-diphenylbenzo[c]thiophene 40, while with Oxone a highly regioselective oxidized product, i.e. l,4-dihydro-l,4-diphenyl-2,3-benzodithiin 2,2-dioxide 41, was formed (equation 58). 

The 2-bromo-4,6-dihydrothieno[3,4-, ]thiophene-5,5-dioxide 211 was used in the synthesis of 5-(5,5-dioxo-5,6-dihydro-477-5A -thieno[3,4-, ]thiophen-2-yl)-3,3"-dipentyl[2,2 5, 2"]terthiophene 213 by Suzuki cross-coupling reaction with 5-bromo-3,3"-dipentyl-[2,2 5, 2"]terthiophene 212 (Scheme 20) <1998S1372>. 

In an ingenious application of the extrusion reaction, 1-alkenyl-1,3-dihydro-benzo[c]thiophene 2,2-dioxides have been thermolyzed the diene system so generated undergoes an intramolecular Diels-Alder reaction with the isolated double bond in the side chain (79HCA2017). An (E) configuration of the diene is necessary for this purpose (Scheme 233). The by-products are styrenes arising from the (Z)-isomer. The same approach has also been used to prepare a steroid derivative (Scheme 233) (80JOC1463). 

The mass spectra of 2-phenyl-, 3-phenyl-, and 3-methyl-2-phenyl-benzo[6]thiophene have been discussed, and tentative structural assignments of the main fragment ions have been made.121 The mass spectra of benzo[6]thiophene-l, 1-dioxide and its 2,3-dihydro derivative have been examined in detail.121> 127 The partial mass spectrum of 2,3-dihydrobenzo[6]thiophene has been recorded.124... 

Benzo[6]thiophene-l,1-dioxides, but not the 2,3-dihydro-1,1-dioxides or the parent benzo [6]thiophenes, are reduced and can be estimated polarographically.200,201... 

When the aromaticity of the thiophene ring in benzo[6]thiophene is destroyed, substitution is governed by the same factors which govern substitution in benzene derivatives. Thus, benzo[6]thiophene-l,l-dioxides and their 2,3-dihydro derivatives undergo substitution in the... 

The sulfones of 4-benzo[6]thienyl-ZV-methylcarbamate and its 2,3-dihydro derivative possess insecticidal activity.610 Several mero-cyanine dyes have been prepared from thioindoxyl-1,1-dioxide,735 736 and a number of 2-arylbenzo[6]thiophene-l, 1-dioxides are fluorescent and are useful commercially (e.g., as dyes 737 and in photographic films738). 2-(p-Isocyanatophenyl)benzo[6]thiophene-l, 1-dioxide has been incorporated in copolymers of use in the printing industry-302... 

With chlorine or bromine, 3a,7a-dihydrobenzo[6]thiophene-l,l-dioxide (107) affords unidentified tetrahalogeno derivatives.750 Elimination of hydrogen chloride from 2,3-dichloro-2,3-dihydro-benzo[6]thiophene-l,1-dioxide occurs on treatment with pyridine to give 2-chlorobenzo[6]thiophene-1,1-dioxide.473... 

Supercritical carbon dioxide with a minute co-solvent addition is an effective medium for the 1,3-dipolar cycloaddition of azomethine ylides with DMAD to produce substituted pyrroles.67 The 1,3-dipolar cycloaddition of nitrile ylides [e.g. benzonitrile (4-nitrobenzylide) and 4-nitrobenzonitrile(benzylide)] with acrylamides provided a synthesis of 3,4-dihydro-2//-pyrroles with moderate to good yields.68 The Pt(II)-or Au(III)-catalysed 3 + 2-cycloaddition of the transition metal-containing azomethine ylide (63) with electron-rich alkenes provided a carbene complex (64), which yields tricyclic indoles (65) having a substituent at 3-position (Scheme 17).69 The 1,3-dipolar cycloadditions of azomethine ylides with aryl vinyl sulfones are catalysed by Cu(MeCN)4C104-Taniaphos with nearly complete exo- selectivity and enantioselec-tivities up to 85% ee.10 The 3 + 2-cycloaddition of benzol/>]thiophene 1,1-dioxide... 

Dihydrobenzo[c]thiophene may be oxidized to its sulfone (Table VII) with peracetic acid,28,69,87,88 aqueous hydrogen peroxide,9 or potassium permanganate,21 and when benzocyclobutene and 1,2-diphenylbenzocyclobutene are heated with sulfur dioxide, they give l,3-dihydrobenzo[c]thiophene 2,2-dioxide89 and its cis-1,3-diphenyl derivative (83),69,90 respectively [Eq. (5)]. 1,3-Dihydro-benzo[c]thiophene 2,2-dioxide also arises when the thiadiazepine (17b) is heated just above its melting point (175°-180°).34a When sulfur dioxide is passed into a solution of diphenyldiazo-... 

We have already mentioned that l,3-diphenyl-l,3-dihydrobenzo-[c]thiophene 2,2-dioxide gives 9-phenyl-9,10-dihydroanthracene as the major product [Eq. (6)] on being heated. Unlike 1,3-dihydro-... 

The reaction of 3,4-bis(halomethyl)thiophenes with sodium sulfide and primary amines gives l//,3//-thieno[3,4-c]thiophenes (103) and 5,6-dihydro-47/-thieno[3,4-c]pyrroles (104), respectively. Some of the cyclizations are adversely affected by ortho substituents (X) (69JOC333). The method has been used to prepare l,3,4,6-tetrahydrothieno[3,4-c]pyrrole 2,2-dioxides (73JHC785). 

Thiophen 2,5-Dihrom-2,5-di-tert.-butyl-2,5-dihydro- -1,1-dioxid V/4, 72... 

The reaction of ( , )-2,4-hexadiene with sulfur dioxide at room temperature affords a single dia-stereomeric m-2,5-dihydro-2,5-dimethyl thiophene 1,1-dioxide (m-13) in 70 % yield123,124. The addition of sulfur dioxide to ( ,Z)-2,4-hexadiene is a much slower reaction and requires elevated temperatures which results in epimerization of the trans-adduct trans-13 to its d.v-isomer d.v-13. Thus, after 12 hours at 96 °C both diastereomers of 13 are present in roughly equal amounts124. 

C5H802S 2,5-dihydro-3-methyl-thiophene 1,1-dioxide 1193-10-8 25.00 1.1370 2 5416 C5H10N2O2 2,3-pentanedione dioxime 4775-86-4 25.00 1.1011 2... 

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