Nitrogen groups oxidative cleavage

The amide type local anesthetic lidocaine is broken down primarily in the liver by oxidative N-dealkylation. This step can occur only to a restricted extent in prilocaine and articaine because both carry a substituent on the C-atom adjacent to the nitrogen group. Articaine possesses a carboxymethyl group on its thiophen ring. At this position, ester cleavage can occur, resulting in the formation of a polar -COO group, loss of the amphiphilic character, and conversion to an inactive metabolite. 

Finally, a third means of ligand formation from an imidazolium cation, described by Dupont and co-workers, should be mentioned here [34]. They investigated the hydrodimerization/telomerization of 1,3-butadiene with palladium(II) compounds in [BMIM][BF4] and described the activation of the catalyst precursor complex [BMIM]2[PdCl4] by a palladium(lV) compound formed by oxidative addition of the imidazolium nitrogen atom and the alkyl group with cleavage of the C-N bond of the [BMIM] ion, resulting in bis(methyHmidazole) dichloropalladate (Scheme 5.2-5). However, this reaction was only observed in the presence of water. 

The oxidative cleavage/reductive amination sequence was readily scaled. After standard aqueous workup, the final manipulation involved a simple filtration through silica gel to remove salts, polar by-products, and residual osmium from 5. The success of this procedure stems from the remarkable nonpolar nature of the tertiary amine. In the favored chair conformation, the 3,5-bicyclic aryl group shields the axial nitrogen lone pair and ensures an equatorial disposition of the benzyl group (Figure... 

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