Formats alkoxymethyl ethers

A study of the reductive cleavage of a series of alkoxymethyl ethers using the glucose backbone shows that, depending on the reagent, excellent selectivity can be obtained for deprotection vs. methyl ether formation for most of the common protective groups. ... 

Formats s. a-Nitroformals —, mixed s. Alkoxymethyl ethers Formamide... 

A very convenient hydroxymethylation process has been developed based on the Sml2-mediated Bar-bier-type reaction. Treatment of aldehydes or ketones with benzyl chloromethyl ether in the presence of Smh provides the alkoxymethylated products in good to excellent yields. Subsequent reductive cleavage of the benzyl ether provides hydroxymethylated products. Even ketones with a high propensity for enolization can be alkylated by this process in reasonable yields. The method was utilized by White and Soners as a key step in the synthesis of ( )-deoxystemodinone (equation 27). This particular ketone substrate resisted attack by many other nucleophilic reagents (such as methyllithium) owing to conpeti-tive enolate formation. 

Silyl enol ethers serve as precursors to a variety of -(substituted methyl) ketones (Scheme 54). Trimethylsilyl trifluoromethanesulphonate catalyses the formation of a-alkoxymethyl ketones from dialkoxymethanes in the presence of a sterically hindered nitrogen base, and titanium tetrachloride catalyses the site-specific ureidoalkylation of silyl enol ethers of cycloalkanones by reaction with chloromethyl carbamates. Mannich dimethylaminomethylation can be... 

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