P-Phenylbenzyl ethers

Pd/C, H2, EtOAc, >52% yield. The p-phenylbenzyl ether is more easily cleaved by hydrogenolysis than are normal benzyl ethers. This property was used to great advantage in the deprotection of the following vineo-mycinone intermediate ... 

Cleavage of benzyl ethers3 Anhydrous FeCl3 in CH2C12 cleaves carbohydrate benzyl and p-phenylbenzyl ethers at 25° without effect on methyl ethers or acetate and benzoate groups. Yields are usually >70%. 

The section on the formation of benzyl ethers should be consulted. Such biphenyl-methyl ethers have also been prepared using a Suzuki coupling with a 4-bromobenzyl ether. p-Phenylbenzyl ethers are more stable to acid than the PMB ethers (60°C in aq. AcOH or TFA, CH2CI2, rt, several hours) ... 

Iron chloride exhibits Lewis acidity to readily cleave C-O bonds of ethers, acetals, and ketals (silyl ethers, later). Anhydrous FeC in dichloromethane can cleave benzyl and p-phenylbenzyl ethers of sugar skeletons, for example (166), in a few minutes at room temperature. Methyl ethers and several acyl groups are not affected under the reaction condition (Scheme 16.46) [53]. 

Takeda R, Zask A, Nakanishi K, Park M H 1987 Additivity in split cotton effect amplitudes of p-phenylbenzyl ethers and p-phenylbenzoates. J Am Chem Soc 109 914-915... 

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