Dakin–West reaction

The Dakin - West reaction is a name reaction in organic chemistry, which is named after Henry Drysdale Dakin and West Randolph. Is a reaction for the conversion of α -amino acids in α -acetamido -ketones by acetic anhydride and a base (e.g. pyridine). It always arise racemates of amino ketones. The reaction may, however, not be confused with the Dakin reaction.

Reaction mechanism

The reaction mechanism is initiated by the activation and acylation of the acid 1 and 3 leads to the mixed anhydride The amide acts as a nucleophile for the azlactone cyclization to 4 leads to a deprotonation anion 5 and a further acylation obtained ring opening and give the ester 7. Upon formation of an acid 8 takes place decarboxylation and the desired amino ketone 10 is formed.

In the reaction must be carried out with pyridine as base and / or solvent under reflux. With the addition of catalytic amounts of 4-dimethylaminopyridine ( DMAP), the reaction proceeds even at room temperature.