Cleavage methoxyphenyl methyl

Using day supported ammonium nitrate (dayan), selective deprotection of methoxyphenyl methyl (MPM) ether has been achieved recently using microwave irradiation in solvent-free conditions (Scheme 6.15) [56]. The same reagent has been used for the cleavage of tetrahydropyranyl (THP) ethers. A similar selective preparation and deavage of THP ethers has been achieved under microwave irradiation catalyzed by iodine [57] or neat reaction in an ionic liquid [28],... 

R = alkyl, alkenyl, alkynyl, aryl, acetate, ester, benzyl or silyl ether groups Scheme 6.15 Cleavage of methoxyphenyl methyl (MPM) ethers using clayan. 

The 4,4 -dimethoxydiphenylmethyl (Ddm) group, or to be more precise bis(4-methoxyphenyl)methyl, is another activated arylmethyl group that is labile towards oxidative and acidic cleavage. It has been used to protect lactams and in the example shown in Scheme 8.195, cleavage was effected with CAN. ... 

The BBrs reaction with 1. l-dimethoxy-2.4.6-di-tert-butyl-4-(4 -methoxyphenyl)-X -phosphorin 200 leads to cleavage of both methoxy groups in addition to the methoxy group at the phosphorus, the 4 -methoxy group is attacked. The 2-hydro-4-(4 -hydroxyphenyl)-phosphinic acid methyl ester 201 can be methylated with methyl iodide in methanol/sodium methylate at the phenolic group, leading to 202, which can also be prepared by hydrogen peroxide oxidation of 2.6-di-tert-butyl-4-(4 -methoxy phenyl)-X -phosphorin 204 to 203, followed by diazomethane methylation (see Table 13, p. 61). 

Wooley et al.1511 have described the creation of fullerene-bound dendrimers (Scheme 5.14). Reaction of C60 with bis(p-methoxyphenyl)diazomethane 54 and subsequent cleavage of the methyl ethers afforded a 6-6 methano-bridged fullerene (55) possessing two phenolic moieties, as the major product.1521 Treatment of the bisphenolic fullerene 55 with 2.7 equivalents of the activated dendron (52) afforded the desired substituted fullerene (56) possessing two dendritic arms. 

Oxidative cleavage of cardanol methyl ether has led to 8-(3-methoxyphenyl)octanoic add, 8-(3-methoxyphenyloctaldehyde and the corresponding alcohol (ref. 226). A range of substituted 8-aryloctanoic acids have been prepared having chloro, bromo and nitro groups (X) as well as different alkoxyl substituents (R) (ref.302). Complete removal of the sidechain of cardanol methyl ether by way of a benzylic hydroperoxide, as for cumene hydroperoxide, to afford 3-methoxyphenol would appear to be possible. 

Reductive cleavage of the /tara-methoxyphenyl (PMP-) group released the primary alcohol and the compound was converted into the corresponding methyl glycoside upon reaction with methanol in the presence of PhsP.HBr [65]. Subsequently, the primary alcohol was replaced by iodine to yield 68 to pave the way for the introduction of the exomethylene functionality required for the key Perrier s carbocy-clization reaction. Carbocycle 70 was obtained after exposure of 5-enopyranoside 69 to Hg(OCOCp3)2 in acetone/acetate buffer and the subsequent p-elimination. The synthesis of the C-ring of the alkaloid was completed by 1,4-reduction and formation of the vinyl triflate 71 with the Comins reagent. 

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