4- methoxy-2-substituted

The reaction of methoxy-substituted 1,4-dihydroatomatic systems is a general one. Other condensed systems react ia a similar manner, for example, 3,6-dimethoxy-1,4,S,8-tetrahydronaphtha1ene and derivatives of anthracene (35) and xanthene (36) (74). The proposed method enables synthesis of the tri-and tetracarbocyanines where the whole chromophore is iategrated iato a rigidizing skeleton. Asymmetrical polymethines can also be obtained similarly. 

Production of cellulose esters from aromatic acids has not been commercialized because of unfavorable economics. These esters are usually prepared from highly reactive regenerated cellulose, and their physical properties do not differ markedly from cellulose esters prepared from the more readily available aHphatic acids. Benzoate esters have been prepared from regenerated cellulose with benzoyl chloride in pyridine—nitrobenzene (27) or benzene (28). These benzoate esters are soluble in common organic solvents such as acetone or chloroform. Benzoate esters, as well as the nitrochloro-, and methoxy-substituted benzoates, have been prepared from cellulose with the appropriate aromatic acid and chloroacetic anhydride as the impelling agent and magnesium perchlorate as the catalyst (29). 

Several methoxy-substituted benzyl ethers have been prepared and used as protective groups. Their utility lies in the fact that they are more readily cleaved oxidatively than the unsubStituted benzyl ethers. The table below gives the relative rates of cleavage with dichlorodicyanoquinone (DDQ). ... 

The magnitude of the anomeric effect depends on the nature of the substituent and decreases with increasing dielectric constant of the medium. The effect of the substituent can be seen by comparing the related 2-chloro- and 2-methoxy-substituted tetrahydropy-rans in entries 2 apd 3. The 2-chloro compound exhibits a significantly greater preference for the axial orientation than the 2-methoxy compound. Entry 3 also provides data relative to the effect of solvent polarity it is observed that the equilibrium constant is larger in carbon tetrachloride (e = 2.2) than in acetonitrile (e = 37.5). 

It will be recalled that the methoxy-substituted aromatic ring was intended to serve as a stable surrogate for the 7-lactone ring contained within compound 13 (see Scheme 1). This electron-rich aro-... 

Substituted 2-phenoxyphenylacetic acids readily cyclize under Friedel-Crafts conditions or acid catalysis to give dibenz[Z>,/]oxepin-10(l l//)-ones.71 85,104- 108 When this reaction is carried out in methanolic hydrochloric acid the 10-methoxy-substituted dibenz[6,/]oxepin system 9a can be isolated.109 5-(Nitro-2-phenoxyphenyl)-2-oxopropanoic acid undergoes cyclization in the presence of polyphosphoric acid yielding the carboxylated dibenzoxepin 9b.107... 

Some thermal rearrangement reactions of 1-benzoxepins show the participation of the solvent in the formation of stable products, e.g. 6172,247 and 7.177 The synthesis of methoxy-substituted 1-benzoxepins by O-methylation of the anions generated by the deprotonation of the respective oxo derivative with ferf-butoxide is often limited by the rapid aromatization to methoxy-substituted naphthalenes, e.g. 816 and 9,173 under the reaction conditions.16,173... 

The oxo group of 9a is reduced by sodium borohydride to the corresponding alcohol, which can be dehydrated with /Moluenesulfonic acid. Subsequent alkylation with dimethyl sulfate and potassium im-butoxide gives the 5-methoxy-substituted 1-benzothiepin 13 in 45 % yield.90... 

Exclusive trims attack of the nucleophile is also observed with 2,3-epoxycyclopentanones 1559. In contrast to 2-alkyl- and 2-methoxy-substituted cyclopentanones, preferential trans attack to 2,3-epoxycyclopenlanones occurs with alkyl, ethenyl, and ethynyl nucleophiles. Thus, there is no assistance by the epoxidic oxygen for cis attack. Due to the geometry of the molecule, chelation-controlled cis attack is not possible39 60. 

A subsidiary approach involves nuclear modification of the arylsilanes so obtained. The requisite organometallics can be prepared from aryl halides, or by deprotonation of a suitably activated (c.g. methoxy-substituted) arene. A more specialized route involves cycloaddition between alkynylsilanes and diynes. 

The rhodium complex of the (R,R)-counter-enantiomer of (S,S)-BisP achieved a high level of ee (97%) in the asymmetric hydrogenation of 3-methoxy-substituted substrate (S)-122 (Scheme 25), which constitutes a precursor to the acetylcholinesterase inhibitor SDZ-ENA-713 (123). 

Substituents on the aromatic ring play a critical role in determining whether or not phenalkylamines possess DOM-like activity. Hallucinogenic activity is commonly associated with methoxy-substituted derivatives (Shulgin 1978) for this reason, much of this work has focused on these types of agents. 

Methoxy-Substituted Derivatives. Phenalkylamines lacking aromatic substituents do not produce DOM-like stimulus effects. None of the three possible monomethoxy derivatives, 2-methoxy-(OMA), 3-methoxy-(MMA), or 4-methoxyphenylisopropylamine (PMA), produce DOM-like effects. Of the six dimethoxy analogs (DMAs) (i.e., 2,3-DMA, 2,4-DMA, 2,5-DMA, 2,6-DMA, 3,4-DMA, and 3,5-DMA), only the 2,4- and 2,5-dimethoxy derivatives 2,4-DMA and 2,5-DMA, respectively, are active. These two agents are essentially equipotent and are approximately one-tenth as potent as DOM. For purposes of comparison, the potencies of 2,5-DMA and DOM are 23.8 and 1.8 pmol/kg. Five trimethoxy analogs (TMAs) have been examined 2,3,5-TMA is approximately one-third as potent as... 

Glennon, R.A. Young, R. and Hauck, A.E. Strueture-aetivity studies on methoxy-substituted phenylisopropylamines using drug diserimination methodology. Pharmacol Biochem Behav 22 723-729, 1985. 

The same (3-alkoxy effect appears to be operative in a 2 -methoxy substituted system.111... 

Wan, P. Chak, B. Structure-reactivity studies and catalytic effects in the photosolvolysis of methoxy-substituted henzyl alcohols.7. Chem. Soc., PerkinTrans. 2 1986,1751-1756. 

In contrast to the dihalogens, there are only a few spectral studies of complex formation of halocarbon acceptors in solution. Indeed, the appearance of new absorption bands is observed in the tetrabromomethane solutions with diazabicyclooctene [49,50] and with halide anions [5]. The formation of tetrachloromethane complexes with aromatic donors has been suggested without definitive spectral characterization [51,52]. Moreover, recent spectral measurements of the intermolecular interactions of CBr4 or CHBr3 with alkyl-, amino- and methoxy-substituted benzenes and polycyclic aromatic donors reveal the appearance of new absorption bands only in the case of the strongest donors, viz. Act = 380 nm with tetramethyl-p-phenylendiamine (TMPD) and Act = 300 nm with 9,10-dimethoxy-l,4 5,8-... 

The present homoallylation with siloxy- and methoxy-substituted dienes may be of great synthetic use. The product 42 is easily converted to anti-5-phenyl-5-hydroxy-3-methylpentanal (Scheme 9) hence the diene 41f may be regarded as a synthetic equivalent of a bis-homoenolate of 3-methylbutanal, being capable of introducing 1,3-anti relationship between the methyl and hydroxy groups in the product. 

Meisenbach M, Echner H, Voelter W. New methoxy-substituted 9-phenyl-xanthen-9-ylamine linkers for the solid phase phase synthesis of protected peptide amides. Chem Commun (Cambridge) 1997 849-850. 

Methyl- and methoxy-substituted polyselenophenes have also been electropoly-merised on platinum [54], and as found for other substituted monomers, they poly-... 

The low specificity of electron-donating substrates is remarkable for laccases. These enzymes have high redox potential, making them able to oxidize a broad range of aromatic compounds (e.g. phenols, polyphenols, methoxy-substituted phenols, aromatic amines, benzenethiols) through the use of oxygen as electron acceptor. Other enzymatic reactions they catalyze include decarboxylations and demethylations [66]. 

Rh2(OAc)4-catalyzed decomposition of m-methoxy-substituted diazoketones 244 furnishes 6-methoxy-2-tetralones rather than the expected bicyclo[5.3.0]decatrienones. This demonstrates that the direction of ring opening in the norcaradienone intermediate 245 may well be influenced by the nature and position of a substituent. 

Laccase is one of the main oxidizing enzymes responsible for polyphenol degradation. It is a copper-containing polyphenoloxidase (p-diphenoloxidase, EC 1.10.3.2) that catalyzes the oxidation of several compounds such as polyphenols, methoxy-substituted phenols, diamines, and other compounds, but that does not oxidize tyrosine (Thurston, 1994). In a classical laccase reaction, a phenol undergoes a one-electron oxidation to form a free radical. In this typical reaction the active oxygen species can be transformed in a second oxidation step into a quinone that, as the free radical product, can undergo polymerization. 

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