Arylmethyl methyl ethers

Photolysis of benzene solutions of l-methoxycarbonyl-2-naphthylmethyl 2,6-di-methyl substituted phenyl ethers induces C-O cleavage with formation of 2,4-cyclohexadienone intermediates which are subsequently photo-rearranged into meta substituted phenols. In methanol, 9-anthrylmethoxy-pyrid-2-one or l-pyrenylmethoxypyrid-2-one undergo photoheterolysis to give the C-O heterolysis products l-hydroxypyrid-2-one and the arylmethyl methyl ether, together with 2-pyridone, aryl-substituted methanol and aryl aldehyde derived from homolysis of the N-O bond. Evidence shows that an intramolecular exciplex plays a crucial role in C-O bond heterolysis. 

Arylmethyl methyl ethers can be alkylated (BuLi, hexane-THF, -40° RX), whereas A,A-diethylbenzyl and cinnamyl carbamates undergo disilylation using BuLi as the base. 

Scheme 5.40 Ni-catalyzed methylation of arylmethyl methyl ethers [113].

Alonsono and co-workers [146] have used substituted 1-naphthyl and phe-nylphosphonium chlorides as precursors for the generation of the corresponding arylmethyl radicals and cations in both nanosecond LFP and product studies. For instance, the salt 101 has a quantum yield for cation formation of 0.71 in methanol and the sole product observed was the corresponding methyl ether. No transient radical was observed in this solvent. In contrast, in 5% acetonitrile in dioxane, the radical was observed but now the cation was absent. No fluorescence was observed in either solvent suggesting that Si is very reactive. Redox potentials indicate that the conversion of the radical/radical ion pair to the cation/triphenyl-phosphine pair would be exothermic by some 25 kcal/mol. Therefore, both heterolytic cleavage from Si or homolytic cleavage followed by electron transfer were suggested as possible pathways for cation formation. 

Catalysis [1, 499, after citation of ref. 32], Canadian chemists323 observed that triphenylcarbinol was converted into the methyl ether in 90% yield by treatment with iodine in methanol. The reaction is general for arylmethyl alkyl ethers. Although iodine functions as a catalyst, highest yields are obtained when it it used in an... 

Cobalt catalysts also promote the cross-coupling reaction of aryl halides, alkenyl halides, and allyl methyl ethers to yield arylmethyl-, allyl-, and homoallyltrimethylsilanes, respectively (eq 25). ... 

A relay Suzuki coupling of o-iodophenyl methallyl ether affords 3-arylmethyl-3-methyl-2,3-dihydrobenzofurans. ... 

Benzyhc methylation of primary arylmethyl ethers can be achieved by reaction with methylmagnesium bromide in toluene at room temperature in the presence of NiCljjdppf) (2mol%) anddppf (l,l -bis(diphenylphosphino)ferrocene) (2mol%) [112]. The transformation tolerates a number of substrates, but heavily depends... 

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