Optically active β-amino acids,especially β2-amino acids with a stereocenter at the α-position,are known as important core structures widely emerged in various natural products and pharmaceutical compounds.1 Recently,we have successfully developed a highly efficient rhodium-catalyzed conjugate addition/enantioselective protonation of arylboronic acids to N-tosyl protected α-aminomethyl tert-butyl acrylate through the use of a chiral diene ligand with water as proton source,giving access to a series of enantioenriched β2-amino esters in high yields with excellent enantioselectivities(up to 98%ee).2 The synthetic utility of the obtained unique β2-amino esters is demonstrated by efficient transformation into particularly interesting benzo-heterocycle architectures.