4-methoxy-6- benzo

NOz HCOONH4/Pd — C/CHgOH (trncken) 3- Amino-4-methoxy-benzoe- 75 7... 

NOz 9CHj f VDY T ° C6H5 HsC,OOC T M SnCVCjHjOH/HCl/HjO 20° 12 h 5- (2-Amino-4-ethoxycar-bonyt-phenoxy) -3-benzyl-oxy-4-methoxy-benzoe-sdure-ethylester 70 6... 

Friedel-Crafts acylation of benzo[6]thiophene usually gives a mixture of 2- and 3-substituted isomers, in which the 3-isomer predominates (Section 3.14.2.4). However, various electron-releasing groups elsewhere on the ring system may favor 2-acylation. Certainly 3-alkyl- or 3-methoxy-benzo[h]thiophenes are acylated exclusively in the 2-position, and 5,6-dimethoxy-, 5,6-methylenedioxy- and 6-ethoxy-benzo[f>]thiophenes are acylated predominantly in the 2-position (70AHC(11)177). 

Both 2- and 3-alkoxybenzo[6 Jthiophenes may be obtained by alkylation of the appropriate hydroxy derivative, but there are competing side reactions (70AHC(11)177). 2-Methoxy-benzo[6 Jthiophene can be prepared by heating 2-bromobenzo[6 Jthiophene with sodium methoxide, and 3-methoxybenzo[7> Jthiophene is obtained by similar treatment of 3-bromobenzo[6 Jthiophene. Alkylation of 3-hydroxybenzo[6 Jthiophene-2-carboxylic ester is more efficient, giving the 3-alkoxy derivative in good yield, and this in turn can be hydrolyzed and decarboxylated in adequate yields (equation 81). 

Both ortho and para cyclization are observed with 3 -hydroxy- and 3 -methoxy-benzo-phenones when DDQ is used as the oxidant. This result was taken to imply the generation of a phenoxonium ion (516) from the 3 -methoxy compounds, which electrophilically attacks the activated methoxyphenyl ring (Scheme 190) (69JCS(C)2761>. 

The maximum bathochromic shift of the zone B bands of methoxy-benzo[6]thiophenes occurs with the 6-substituted compound a hypsochromic shift of the A and B bands is observed for 7-methoxy-benzo[6]thiophene.85,159... 

The continuous-flow measurements showed the presence of two major compounds. They were afterwards assigned by stop-flow measurements. Peak 1 eluted at 25min, and peak 2 at 41min (see Figure 7.3.2.3). Comparison between the H-NMR spectra recorded during the stop-flow experiments showed that the two compounds are very similar (Figure 7.3.2.5). Peak 1 could be assigned to 2-ethylbenzo-l,4-quinone and peak 2 to 2-ethyl-3-methoxy-benzo-1,4-quinone. 

Tribromo-m-cresol is oxidized by chromium trioxide in 70% acetic acid at 70-75 °C within 10 min to dibromo-m-toluquinone (3,5-dibromo-2-methyl-p-benzophenone) in 77% yield [559]. 2-BVomo-4-hy-droxy-5-methoxybenzyl alcohol treated with Fremy salt at pH 6 at room temperature for 1 h gives an 84% yield of 2-bromo-5-methoxy -benzo-quinone [487]. 4-Benzyl-2,6-dibromophenol, on oxidation with bromine in a sealed tube, yields 2,6-dibromophenylchinomethide [732] (equation 312). The oxidation of 2,5-di-tert-butyl-4-methoxyphenol with mercuric oxide or... 

The synthesis of some novel fluoro-substituted benzo[a]phenothiazines and their nucleosides as possible antimicrobial agents was reported [196]. 6-(2-Methoxy-5-methyl/2-methoxy-4-chloro-5-methyl-anilino)-9-fluoro-5H-b enzo [ a ] phenothiazine-5-ones/thiones, 12H-benzo [ a ] phenothiazine-5-ols, 5-acetoxy-12H-b enzo [ a ] phenothiazines, 5-methoxy-12H-benzo [ a ]phenothia-zines and nucleosides, viz N-(2,3,5-lri-0-bcnzoyl-f>-D-ribofuranosyl)-6-(2-methoxy-5-methyl/2-methoxy-4-chloro-5-methyl-anilino)-9-fluoro-5-acetoxy benzo[a]phenothiazines and 9-fluoro-5-methoxy benzo[a]phenothiazines, were synthesized and tested for their antimicrobial activity. The structures of novel compounds were proposed on the basis of elemental analyses, IR and and 19F NMR studies. 

Of the four monohydroxybenzo[c]cinnolines the 2- and the 4-isomers are potentially tautomeric with the corresponding quinonimines, e.g., 90 91. While the ultraviolet spectrum of 2-hydroxybenzo[c]cinnoIine shows close correspondence to that of the 2-methoxy compound in neutral solution, spectra of the conjugate acid and conjugate base both indicate appreciable charge-resonance between the 2- and 6-positions, and methylation of 90 with dimethyl sulfate or diazomethane gives rise to mixtures of 2-methoxy-benzo[c]cinnoline and the quinonimine 92. ... 

FIGURE 12.6 Dibenzofuran XVII was obtained by UV irradiation of methoxy-/ -benzo-quinone. (After Forsskahl, I., Gustafsson, J., and Nybergh, A., Acta. Chem. Scand., B 35, 389-394, 1981.)... 

These quinones may be prepared by oxidation of the corresponding 7-hydroxy compound with Fremy s salt the presence of a 3-phenyl group hinders oxidation in the 4-position, with the result that a 6,7-quinone is then also formed.497,498 Anodic oxidation of a 5-substituted 4-methoxy-benzo[b]thiophene in boiling methanol gives the 4,7-bisacetal, acidic hydrolysis of which gives the corresponding 4,7-quinone.499 2,3-Dichloro-... 

A novel alkaloid was isolated from the stem of E. arborescens Roxb. Its structure and stereochemistry were elucidated on the basis of the ID and 2D homonuclear and heteronuclear NMR spectroscopic data, and it was characterized as 10-hydroxy-ll-methoxy-benzo[g]hexahydroindolizin-3-one and named erythrinarbine [36],... 

Hydroxy-4-methoxy-benzo-phenone-5-sulfonic acid... 

Oder 6t)-BFom-2-methoxy-benzo< ohinon-(l,4)-oxim-(4)-benzoat 0, 267. 

CgiHuNsOi 5-Amino-2-methoxy-benzo= uion-(1.4).imid-(l)-[4-(4-acetamino-anilino)-anil]-(4) 13 1 204. 

C,H,CIOs 6-Chlor-2.3-dio -5-methoxy-benzo< ohiiuin-(1.4) odei 8-Chlor-2.5-diOCT-3-methoxy-benzachinon-(1.4) 8, 490. 

Weiterhin kommt Primulaverin (98), das Primverosid des 2-Hydroxy-5-methoxy-benzoesauremethylester, Schmp. 194—196°, aD = —64° (Was-ser), in den unterirdischen Organen von Primula veris, Primula elatior und Primula vulgaris vor 281). In Primula veris und Primula kewensis tritt Primverin (99), das Primverosid des 2-Hydroxy-4-methoxy-benzoe-sauremethylester auf (vgl. 281). 

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