Diarylmethyl ethers and Pd salts or complexes: a perfect combination for the protection and deprotection of alcohols

Primary and secondary alcohols are easily protected as diphenylmethyl (DPM) or bis(methoxyphenyl)methyl (BMPM) ethers in good yield using PdCl₂(CH₃CN)₂ as catalyst in dichloroethane at 60 or 20 °C, respectively. These conditions are compatible with other functional and protecting groups such as halides, esters, acetal, benzyl, para-methoxybenzyl, benzyloxycarbonyl, and tert-butyldiphenylsilyl. Good selectivity was observed in favor of primary over secondary alcohols. Deprotection of diphenylmethyl or bis(4-methoxyphenyl)methyl ethers was efficiently achieved at room temperature using PdCl₂(CH₃CN)₂ in dichloroethane in the presence of 10 equiv of ethanol.     

Copper(II) bromide as an efficient catalyst for the selective protection and deprotection of alcohols as bis(4-methoxyphenyl)methyl ethers

In a cheap and eco-friendly process, primary and secondary alcohols were easily protected as bis(methoxyphenyl)methyl (BMPM) ethers in good yields using CuBr₂ as a catalyst in acetonitrile at room temperature. Deprotection could easily be achieved using the same catalyst but in ethanol. Both Cu-catalyzed protection and deprotection were orthogonal to other methods and fully compatible with other functional groups.