Blaise reaction

[4] Bulky aliphatic esters tend to give higher yields.

Steven Hannick and Yoshito Kishi have developed an improved procedure.

The mechanism of the Blaise reaction involves the formation of an organozinc complex with the bromine alpha to the ester carbonyl.

The negative nitrile nitrogen resulting from this attack complexes with the zinc monobromide cation.

The β-enamino ester (tautomer of the imine intermediate pictured above) product is revealed by work-up with 50% K2CO3 aq.