Anodic oxidation, of amides

The anodic oxidation of amides and carbamates is one of the most general and efficient electrochemical reactions known [115]. The primary intermediate... 

The products obtained by the anodic oxidation of amides or carbamates in methanol have the same structures as the compounds which can be synthesized from amides (carbamates), aldehydes and methanol (equation 50). l e regeneration of iminium cations from these a-methoxyamides and subsequent reactions of the iminium cations with nucleophiles such as active methylene compounds or nucleophilic aromatic nuclei is well known under the term amidoalkylation (equation 50). ... 

Anodic oxidation of amides and carbamates on the other hand are far more useful than those of amines. Scheme 46 shows the synthesis of a pharaoh ant trail pheromone in which the anodic oxidation of 2-pyrrolidone is an important step [270]. 

In Scheme 8, five possible electrochemical pathways for the formation of V-acyli-minium ions are represented. Pathway a (see Sec. VIII.A) describes the direct anodic oxidation of amides and carbamates to the intermediated V-acylium ions via removal of one electron from the nitrogen lone pair followed by deprotonation in a-position of the nitrogen atom and further one-electron oxidation. In pathway b (see Sec. VIII.C), a decarboxylative methoxylation of an V-acylated amino acid (Hofer-Moset reaction) leads to the same intermediate. The radical that is formed after anodic decarboxylation is immediately further oxidized to the cation due to the electron donation of the nitrogen. Pathway c (see Sec. VIII.B) describes the anodic oxidation of an V-acylated amino... 

Electrochemical anodic oxidation of amides and N-alkyllactams can be carried out with IV-hydroxy-phthalimide as mediator. Oxidation takes place predominantly at the endocyclic carbon a to the nitrogen. The susceptibility of five-membered rings to oxidation is much higher than that of six-membered rings. 

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