Benzol 6 thiophenes

Reaction Reagent r<°ci Benzo[t lfuran Benzol 6]thiophene... 

The currently accepted name for 1 in Chemical Abstracts is benzol-thiophene. Thionaphthene (or thianaphthene), 1-thiaindene (particularly in Russian literature) and, less commonly, benzothiofuran... 

The UV spectrum of 3,3-dimethyl-2-imino-2,3-dihydrobenzo[i>]-thiophene (14) is quite similar to that of 2,3-dihydrobenzo[6]thio-phene.118 On the other hand, the spectrum of 2-aminobenzo[6]thio-phene diverges from that of 14, but closely matches that of benzol-thiophene. 2-Aminobenzo[6]thiophene exists, therefore, mainly as the amino tautomer.112-114 On the contrary, thiooxindole (15) exists in solution mainly as the oxo form since its spectrum closely resembles that of the thiolactone (16) and the imine (14).113... 

Unlike benzofuran, pyrrole, and certain indoles,400 benzol-thiophene does not react with dichlorocarbene.400,401... 

Treatment of 2- or 4-(p-formylphenyl)-2/f-l,2,3-triazoles with p-tolyl-substituted heterocycles such as benzo[6]furans,58,63 benzol-thiophenes,56,63 benzoxazoles,63,64 benzisoxazoles,54 oxazoles,63 isoxa-zoles,63 oxadiazoles,63,65 benzotriazoles,63 and y-triazolo [ 1,5-a]-pyri-dines19 has led to the formation of a number of new stilbene derivatives some of which are shown in Table XI. 

Untersucht man homologe Reihen, die als Basisgruppen Benzol, Thiophen und Furan-Gruppen sowie Doppelbindungen im Molekiil enthalten, so zeigt sich, daB mit langer werdendem Alkyl die i>-Werte... 

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... 

The last step in the synthesis of the sulfur- and selenium-containing psoralen analogues (174) (7/7-thieno[3,2- ][l]benzothiopyran-7-one, 7//-seleno[3,2-/][l]benzothiophen-7-one, 2//-selenolo [3,2- ][l]benzothiopyran-2-one, and 7//-selenolo[3,2-g][ 1 ]benzoselenopyran-7-one) was the poly-phosphoric acid silyl ether (PPSE)-mediated cyclization of benzol-thiophenes or selenophenes shown in Equation (76) <92H(34)lli9>. 

Competitive metallation experiments with A-methylpyrrole and thiophene and with A-methylindole and benzol] thiophene indicate that the sulfur-containing heterocycles react more rapidly with -butyllithium in ether. The comparative reactivity of thiophene and furan with -butyllithium depends on the metallation conditions. In hexane, furan reacts more rapidly than thiophene but in ether, in the presence of tetramethylethylenediamine (TMEDA), the order of reactivity is reversed. 

The reactions of the lithio derivatives of benzo[A]-fused systems indole, benzo[ ]furan, and benzol/ ]thiophene are similarly diverse. Since indole and benzo[A]thiophene undergo electrophilic substitution mainly in the 3-position, the ready availability of 2-lithio derivatives by deprotonation with -butyllithium is particularly significant. The ready availability of 3-iodoselenophene and hence of 3-lithioselenophene provides a convenient route to 3-substituted selenophenes. 2-Lithiotellurophenes are especially important precursors of tellurophene derivatives because of the restricted range of electrophilic substitution reactions which are possible on tellurophenes. 

Of the three possible substrates, thiophene, benzo[ ]thiophene, and dibenzo[, thiophene, benzo[ ]thiophene is the most easily hydrogenated to the dihydro derivative this is ascribable to the more pronounced olefinic character of the C(2)-C(3) double bond in benzo[, ]thiophene as compared to that in thiophene. There is no example in the literature of the hydrogenation of dibenzothiophene either to the tetrahydro or the hexahydro stage. The hydrogenation of benzol ]thiophene is catalyzed by transition metals such as Ru, Os, Rh, and Ir. An excellent overview of homogeneous catalytic hydrogenation of thiophenic substrates has been presented recently <2004JOM (689)4277>. 

Kropp, K.G., J. A. Goncalves, J.T. Anderson, and P.M. Fedorak. 1994. Microbially mediated formation of benzonaphthothiophenes from benzol/>]thiophenes. Appl. Environ. Microbiol. 60 3624-3631. 

Base-catalyzed proton-deuterium exchange at H-2 and H-3 in benzol-thiophene has been extensively studied,255"258 but the results are contradictory. H-2 is replaced faster than H-3 in benzo[h] thiophene, and faster than H-2 in benzo[i>]furan. The marked ability of the sulfur atom to stabilize the 2-carbanion has been discussed in terms of d-orbital participation, electronegativity, and polarization phenomena, but no convincing conclusions have yet been reached. 

The lability of thieno[3,4-6]thiophene (3) and other iso-annelated systems, such as benzo[c]thiophene and benzole] furan, may be due to the strain effect (Mills-Nixon effect see also Zwanenburg et alP and references therein) in the condensed five-membered ring. The stability of the iso-annelated dithienothiophenes 7—9 is noteworthy. Simple LCAO MO method calculations on benzo[c]thiophene indicate that its instability is due to low specific delocalization energy and high free valence index at position 1. 

Castle and co-workers <1996JHC119, 1996JHC185, 1997JHC1597, 1998JHC1441> used 3-chlorothieno [2,3-3]thiophene-2-carbonyl chloride 280 in the synthesis of the appropriate amides, which by oxidative photo-cyclization gave novel polycyclic heterocyclic ring systems thieno[3, 2 4,5]thieno[2,3-f][l,10]phenanthroline 281, thieno[3, 2 4,5]thieno[2,3-f]naphtho[2,iy ]quinoline 282 and thieno[3, 2 4,5]thieno[2,3-f]naphtho[l,2-g]qui-noline 283, thieno[3, 2 4,5]thieno[2,3-f]naphtho[l,2y ]quinoline 284, thieno[3, 2 4,5]thieno[2,3-f]naphtho[l,2 7]-[l,2,4]triazolo[3,4- ]quinoline 286, thieno[3, 2 4,5]thieno[2,3-f]naphtho[l,2-/]tetrazolo[l,5- ]quinoline 288, benzo[ ]thieno[3, 2 4,5]thieno[2,3-f]quinoline 285, benzo /]thieno[3, 2 4,5]thieno[2,3-f]quinoline 287, benzol/] thieno[3, 2 4,5]thieno[2,3-f]tetrazolo[l,5- ]quinoline 289, and benzo[/jthieno[3, 2 4,5]thieno[2.3-f][l,2,4]triazolo[4,3- ]-quinoline 290. 

Die Synthcse von N-Acetyl-a-hydroxy-glycin und dessen Umsetzung mit aromatischen Nukleophilen wie u.a. Benzol, Toluol, Phenol oder Thiophen kann auch als Eintopf-Verfahren durchgefiihrt werden (45-80% Ausbeute)2. 

Purification and Fractionation of 90% BenzoL—Commercial benzene is far from pure and contains homologues (chiefly toluene) and thiophen as well as basic substances. On removal of the bases with dilute acid and the thiophen with cone, sulphuric acid, fairly pure benzene may be obtained by fractional distillation of the residue. 90% benzol contains about 80—82% benzene, 14—15% toluene, and about 3% xylenes. The term means that 90% by volume of the benzol can be distilled off up to 100°. 

Als Aromaten konnen Benzol, Fluorbenzol, Chlorbenzol und Alkylbenzole eingesetzt werden. Trimethoxybenzol, 4-Methoxy-toluol, Thiophen oder Furfural reagieren nicht. Die Orientierung bei substituierten Aromaten ist vorwiegend para z.B. im Falle von Toluol oder para und ortho im Falle von ChlorbenzoP38. 

Benzo[b]furan Benzo[fr]thiophene Benzojb]- selenophene Benzol [b]-tellurophene... 

In the benzo[A] and benzol/] heterocycles 220 and 221, where the loss of ring resonance energy on tautomerism is much less than in the nonannulated heterocycles 217, the oxo tautomers 222 and 223 are energetically preferred. 2-Hydroxyindole 220 (X = NH) exists exclusively as the oxo tautomer 222 (X = NH) (oxindole). The hydroxy form of 2-hydroxybenzo[A]thiophene 220 (X = S) is detectable by NMR spectroscopy when its trimethylsilyl ether precursor is... 

The benzols are treated with sulfuric add or by catalytic hydrorefining to remove compounds containing sulfur (thiophene, mercaptans), oxygen (phenols) and nitrogen pyridine, cyanidesi. The refined product is then distilled to ield crude benzene containing the following hydrocarbons . ... 

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