Chloromethyl methyl ether, protecting alcohols

Treatment of the Stille adduct 118 with ethynylmagnesium bromide and protection of the resulting propargyl alcohol with chloromethyl methyl ether (MOMCl) provided the MOM ether... 

If the carbanion of (1) is allowed to react with an aldehyde or ketone, 3-hydroxy aldehydes can be prepared. Since 3-hydroxy aldehydes are usually labile, it is advantageous to trap the adduct (a) with chloromethyl methyl ether as shown for (5). The protected hydroxy aldehydes (6) so obtained can be converted into homoallyhc alcohols by a Wittig reaction. 

Addition of tributylstannyl-lithium to crotonaldehyde and protection of the resulting alcohol with chloromethyl methyl ether gives the stannane (192), which reacts with both alkyl and aryl aldehydes RCHO to form specifically the t/rr o-hydroxy-enol ethers (193). These latter compounds have been used to prepare tra/i5-4,5-disubstituted butyrolactones by hydrolysis and subsequent oxidation. Palladium-catalysed carbonylation of RX in the presence of organotin species constitutes a useful synthesis of unsymmetrical ketones, and in the example reported this year RX is an arenediazonium salt. The reaction, which is basically an aromatic acylation, proceeds in good to excellent yield. Another Pd-catalysed reaction of aromatics, this time aryl bromides, is their reaction with acetonyltributyltin (194), prepared from methoxytributyltin and isopropenyl acetate, to give the arylacetones (195). ... 

The methoxymethyl (MOM) and jS-methoxyethoxymethyl (MEM) groups are used for protecting alcohols and phenols as formaldehyde acetals. These groups are introduced by reaction of an alkali metal salt of the alcohol with methoxymethyl chloride (chloromethyl methyl ether) or -methoxyethoxymethyl chloride. An... 

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