Methoxymethyl Ethers of Phenol

The protection of phenolic hydroxyls as the methoxymethyl ethers can also be achieved effectively under phase transfer conditions in which methoxymethyl chloride is the electrophile. The solid potassium phenoxide salt is solubilized by 18-crown-6 in dry acetonitrile which also contains the alkylating agent [7]. The protection of two phenolic ketones in good yield are formulated in equations 5.7 and 5.8. 

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Methoxymethyl ethers of phenols. Phenols can be converted into methoxy-methyl ethers (Ar0CH20CH3> in 80-95% yield by reaction with chloromethyl methyl ether under phase-transfer conditions. Adogen 464 (6, 10) has been used as catalyst. 

By careful optimisation, Widdowson was able to show that methoxymethyl ethers of phenols are better substrates for alkyllithium-diamine controlled enantioselective deprotonation, and (-)-sparteine 85 is then also the best ligand among those surveyed the BuIi-(-)-sparteine complex deprotonates 162 to give, after electrophiUc quench, compounds such as 164 in 58% yield and 92% ee (Scheme43) [102]. Deprotonation of the anisole complex 125 under these conditions gave products of opposite absolute stereochemistry with poor ee. 

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