The title compound, C20H21NO3, is a derivative of Aib (alpha-aminoisobutyric acid) and is cyclized at the C-alpha position by biphenyl rings. The seven-membered ring possesses C2 symmetry. The C-alpha cyclization causes the backbone to assume a helical conformation in the crystal structure. The packing of the molecules is stabilized by intermolecular C-H...O, C-H...pi and N-H...O hydrogen bonds.