Three-component reactions of CF3-substituted boranes, ethyl diazoacetate and imines

Aryl(methoxy)(trifluoromethyl)boranes, generated in situ, readily react with ethyl diazoacetate and N-(4-methoxyphenyl)imines to give derivatives of β-amino acids. In this process, the electron-deficient borane reacts with the diazo compound followed by trapping of the intermediate boron enolate by the imine. The final products are predominantly produced as syn isomers.