Carbon-Carbon Bond Formation by the Use of Chloroiodomethane as a C<sub>1</sub>Unit. III. A Convenient Synthesis of the Mannich Base from Enol Silyl Ether by a Combination of Chloroiodomethane and<i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>′-Tetramethylmethanediamine
a combination of chloroiodomethane (CH2ClI) and N,N,N′,N′-tetramethylmethanediamine (TMMD) in DMSO as the solvent at ambient temperature. The mechanism of the transformation is discussed on the basis of product analysis and 1H NMR spectral studies. The reagent system CH2ClI/TMMD also provides a convenient route to the Eschenmoser’s salt (Me2\overset+N=CH2,\overset−I).
corresponding Mannich products by various dimethyl(methylene)ammonium salts under a range of reaction conditions. The several methods used to form these derivatives are compared. Excellent approaches to aldehyde derivatives involve treating the enol silyl ether of the carbonyl compound with methyllithium and then an iminium salt, or directly adding the iminium salt to the enol silyl ether. Ketones may be