Benzo thiophenes, 1,3-dihydro

Nitro-, 5-hydroxy-, and 6-bromo-2,3-dihydro-benzo[ ]thiophene-... 

Benzo(6]thiophene halogenation, 57, 294 iodination, 59, 254 resonance energy, 56, 352 Ru, Ir complexes, 58, 150 Benzo[6]thiophene, 3-benzoyl-, reaction with hydrazine, 56, 128 Benzo[l)]thiophene, 3-bromo-, chlorination, 57, 293 Benzo[6]thiophene, 4-fluoro-, 60, 17 Benzo[/>)thiophene, 4,5,6,7-tetrafluoro-2,3-dihydro-2-methyl-, 60, 28 Benzo(e]thiophenes, resonance energy,... 

Biocatalytic asymmetric oxidation of 2,3-dihydrobenzo[. ]thiophene to (—)-(lJ)-sulfoxide in excellent yield has been reported. The enzyme used is a chloroperoxidase from the marine fungus Caldariomycesfumago. This enzyme is relatively stable and does not require any cofactor. Hydrogen peroxide was the oxygen source. Using this system, 2,3-dihydro-benzo[. ]thiophene was converted to the (—)-(i )-sulfoxide in 99.5% yield, with an ee of 99%. Similarly, 1,3-dihydro-benzo[f]thiophene could be oxidized to the corresponding sulfoxide in 80% yield <1998CH246>. 

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>. 

Dioxo-l,2-dihydro- E4, 216 (3-NH2 — 2-COOR — 1 -benzo-thiophen + COCl2)... 

Benzo[/ ]thiophene, 2,3-dihydro-reactions, 4, 849 3-substituted synthesis, 4, 872... 

Similarly, 3-oxospiro[benzo[ ]thiophene-2(3//)-T-cyclopropane] 5 ,5-dioxides 3 and 4 were synthesized starting from phenyliodonium ylide 2 and alkenes with catalysis by bis(acetyl-acetonato)copper(II).49 The ylide is easily obtained in 95% yield from 3-oxo-2,3-dihydro-benzo[6]thiophene 1,1-dioxide and bis(trifluoroacetoxy)iodobenzene. 

Benzo[fr]thiophene 1,1-dioxide and its derivatives are reduced to the corresponding 2,3-dihydro derivatives by catalytic hydrogenation in good yields (Scheme 94). In this reduction, the sulfonyl moiety remains unchanged [13,189, 238, 239]. However, reduction of benzo[ ]thiophene 1,1-dioxide with LiAlH4 affords deoxygenated 2,3-dihydrobenzo[ ]thiophene in 79% yield [233]. Benzo[fr]thiophene 1,1-dioxide was also reduced to the 2,3-dihydro derivative by an electrochemical method (Scheme 95) [240]. 

Benzo[Z>]thiophen 5-Oxides. - Mild methods for the oxidation of 2,3-dihydrobenzo[Z>] thiophens to the sulphoxide have been developed. The photochemical reactions of various 2- and 3-substituted benzo[ ]-thiophen 1-oxides led to different photodimers. From 3-chlorobenzo[b]-thiophen-2-carboxylic acid 1,1-dioxide, 1,3-oxazinones of biological interest were obtained through cyclization reactions with cyanamides and carbodi-imides. Secondary amines add to 2-phenylbenzo [b] thiophen 1,1-dioxide to give 3-amino-substituted 2,3-dihydro-2-phenylbenzo[b]thiophen 1,1-dioxides. " ... 

Dihydro-lH-thio-pyranol[4,3-b] [l]benzo-thiophenes by double ring closure. 

Intramolecular attack of the carbenes shown in Scheme 30a provides benzo[6]cyclo-hepta[(5 ]-furans and -thiophenes, but the nitrogen analogue (X = NH) yields 9,10-dihydro-acridine 81AJC1037). Photolysis of 2-biphenyl isocyanide (Scheme 30b) (72JOC3571) and thermolysis of 2-biphenylsulfonyl diazomethane (Scheme 30c) (72CC893) also result in ring expansion. 

Benzo[b]thiophene-2-carboxylic acid, 2,3-dihydro-synthesis, 4, 921... 

Benzo[b]thiophenium, 1,2,3,5-tetramethyl-theoretical methods, 4, 3 Benzo[b]thiophenium salts preparation, 4, 723-724 Ben2o[b]thiophen-4-one, 4,5,6,7-tetrahydro-synthesis, 4, 905-906 5H-Benzo[b]thiophen-4-one, 6,7-dihydro-synthesis, 4, 900 Benzo[b]thiophyne, 4, 750 1H- 1,3,4-Benzotriazepine, 2,3-dihydro-synthesis, 7, 637 1H-1,2,4-Benzotriazepines synthesis, 7, 638 1,2,5-Benzotriazepines synthesis, 7, 640... 

D) Preparation of 4-[1 -Methyl-Piperidyl-(4 )]-9,10-Dihydro-4H-Benzol4,5]Cyciohepta[1,2-b] Thiophen-(4)-ol 0.94 g of magnesium filings which have been activated with iodine are covered with a layer of absolute tetrahydrofuran and etched with a few drops of ethylene bromide. A solution of 5.0 g of 1-methyl-4-chloropiperidine in 5 ml of tetrahydrofuran is then added dropwise and boiling then effected for a further hour under reflux. After cooling to room temperature, the solution of 4.5 g of 9,lO-dihydro-4H-benzo[4,5] cyclohepta[1,2-b] thio-phen-(4)-one in 5 ml of tetrahydrofuran is added dropwise. 

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... 

Aus Phthalsaure-thioanhydrid wird mit Aluminiumhydrid oder Diboran nahezu quanti-tativ 1,3-Dihydro-(benzo-[c]-thiophen), mit einem Lithiumalanat-UberschuB 2-Hydr-... 

CN 4,9-dihydro-4-( 1 -methyl-4-piperidinylidene)-10//-benzo[4,5]cyclohepta[ 1,2-i]thiophen- 10-onc... 

C 9H,2N0S 34580-09-1) see Ketotifen 4,9-dihydro-4-(l-methyl-4-piperidinylidene)-10/f-benzo [4,5]cyclohepta l,2-l>)thiophen-10-one (C19H19NOS 34580-13-7) see Ketotifen... 

Benzo[c]thiophene is a source of 3-substituted derivatives of 3,4-dihydro-1//-2-benzothiopyrans via ring opening to the dianion and subsequent reaction with electrophiles <96JOC1859>. 

A comparison has been made of the spectra of thienothiophenes 1 and 2 with those of naphthalene and benzo[ft]thiophene and of the spectra of l/f,3i/-thieno[3,4-c]thiophene (112) and of 4,6-dihydro-thieno[3,4-6]thiophene (131) with those of thieno[6]- and thienolc]-cycloalkenes. ... 

Similar reduction of benzo[Z)]thiophene furnishes the 2,3-dihydro derivative and o-ethylthiophenol. ... 

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). 

---