Anisole, metalation

The most common method for removal of the amide MPM group is by oxidation with DDQ or CAN. With CAN, the benzoyl imide is sometimes a byproduct of the reaction (eq 6), but this is easily cleaved by hydrolysis. The amide MPM group is also cleaved by solvolysis in TEA or AlC /anisole. Metalation with t-ButylUthium followed by reaction with oxygen (62%) has been used successfully (eq 7). ... 

When both a-positions are blocked, the highly specific reactivity toward organolithium compounds disappears and metalation depends on the kind of a-substituents present. Thus whereas 2,5-dimethylthio-phene is not metalated at all, 2-methoxy-5-methylthiophene is metalated in the 3-position, similar to the known ortho metalation of anisole. On the other hand, 5-methyl-2-methylthiothiophene is also metalated (in low yield) in the 3-position, in contrast to thioanisole... 

The reactivities of hydrido(phenoxo) complexes of trons-[MH(OPh)L2] (6 M = Ni 7 M = Pt) (L = phosphine) were examined (Eqs. 6.29, 6.30 Scheme 6-16), and a high nucleophiUdty for the metal-bound phenoxide was suggested [9, 10]. Reaction with methyl iodide produced anisole and trans-[MH(I)L2] for both Ni and Pt complexes. Phenyl isocyanate also provided the insertion products into the metal-phenoxo... 

Acylation of aromatic ethers in the presence of a variety of metal chlorides and oxides [52]. The rate enhancement was probably caused by large temperature gradients but was not evaluated quantitatively. Reaction conditions a single-mode stirred tank reactor, fourfold excess of anisole, no solvent. 

When anisole is reduced by an alkali metal in liquid ammonia either a stable, conjugated diolefin or a less stable, unconjugated diolefin can be isolated, the latter being the product when the reaction mixture is neutralized with a strong acid such as ammonium chloride. The free ions, whether they are present to any great extent or not, are the resonance hybrid LXVI. 

Bromodesilylation T-methoxy-l-indanones. Cyclization contrary to the normal para-selectivity of anisole derivatives can be effected by temporary use of an ort/jo-trimethylsilyl group introduced by directed orf/io-metallation (11,75). Thus the anisole derivative 1 undergoes bromodesilylation and hydrolysis to provide 2. This product undergoes cyclization to 3 in good yield on conversion to the lithio salt followed by bromine-lithium exchange (8,65-66). 

Early examples of electron transfer processes are shown in equations (2), (12), and (13). Birch in 1944 followed up the findings of Wooster, and demonstrated that Na metal and ethanol in ammonia reduce benzene, anisole, and other aromatics to 1,4-cyclohexadienes. Birch speculated about the mechanism of this reaction, but did not explicitly describe a radical pathway involving 55 (equation 87) until later, as described in his autobiography. Electron transfer from arenes was found by Weiss in 1941, who obtained crystalline salts of Ci4H]o from oxidation of anthracene. ... 

The above comments should not be taken as claims that anisole and diphenyl ether cannot be metallated by organolithium species. For example, alkyllithiums are known (38,39,40) to react with anisole, usually in the ortho position. However, these reactions are generally slow, particularly at ambient temperature and when the ether is diluted with a hydrocarbon solvent. Our results merely indicate that active center deactivation via metallation of these aromatic ethers is not a serious problem during the time span of our measurements with species that are, at least, partially delocalized (33J ... 

At first sight, electrodeposition of metals from nonaqueous solutions seems to offer a complete solution, there being no source of H present (in a system consisting of e.g., palladium chloride in a phenanthrene-anisole mixture). The potential limits inside which electrodeposition can take place can be far wider than those in aqueous solutions (some 2.0 V). A number of redox potentials in nonaqueous systems are given in Table 7.22. 

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