Eschenmoser's salt
Template:Short description Template:Chembox
In organic chemistry, Eschenmoser's salt (named for Albert Eschenmoser) is the ionic, organic compound Template:Chem2. It is the iodide salt of the dimethylaminomethylene cation Template:Chem2.
The dimethylaminomethylene cation is a strong dimethylaminomethylating agent, used to prepare derivatives of the type Template:Chem2.[1][2] Enolates, silyl enol ethers, and even more acidic ketones undergo efficient dimethylaminomethylation. Once prepared, such tertiary amines can be further methylated and then subjected to base-induced elimination to afford methylidenated ketones. The salt was first prepared by the group of Albert Eschenmoser[3] after whom the reagent is named.
Structure and bonding
Dimethylaminomethylene cation is described as a resonance hybrid of the carbocation and an iminium cation:
The Template:Chem2 atoms are coplanar. The cation is isoelectronic with isobutene.
Preparation
Pyrolysis of iodomethyltrimethylammonium iodide affords the desired salt:[3]
An alternative route starts with bis(dimethylamino)methane:
Related salts
Other salts of the dimethylaminomethylene cation:
- Dimethyl(methylidene)ammonium trifluoroacetate.[4]Template:R
- Dimethyl(methylidene)ammonium chloride (Böhme's saltTemplate:R, after Horst Böhme)
See also
References
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- ↑ E. F. Kleinman in "Dimethylmethyleneammonium Iodide and Chloride" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. Script error: No such module "CS1 identifiers".
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- ↑ a b Script error: No such module "Citation/CS1".
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