Ether, «-butyl dimethylaminomethyl

Prepared in situ from chloroiodomethane and N.M,N./Y-tetramethyldiaminomethane. Prepared in situ from n-butyl dimethylaminomethyl ether and a catalytic amount of Me3SiI or MesSiOTf the exact structure of the aminomethylating agent is unknown. 

Two in situ methods for the generation of A///-dimethyl(methylene)iminium salts, which are limited to reactions with enol silanes, are also available and avoid the need to handle these moisture-sensitive reagents. In the first method, iodide (30) is prepared in situ by treating methyl(methylene)diamine (34) with chloroiodomethane (equation 5) 36,37 DMSO must be used as solvent to achieve maximum yields. Cleavage of n-butyl dimethylaminomethyl ether (35) with TMS-I or TMS-OTf in MeCN comprises the second method (Scheme 5).38 A silyloxonium ion (36) was originally proposed as the reactive aminomethylating species, but a recent 13C NMR study of the reactions of ami-nol ethers with halosilanes in CD3CN-SO2 did detect the presence of iminium salts.39 Use of these methods in reactions with enol silanes is discussed in Section 4.1.2.2.2.iii. 

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