3,3′-[(tert-Butoxy­carbon­yl)aza­nedi­yl]dipropanoic acid

The title compound, C11H19NO6, is an important inter­mediate for the synthesis of cephalosporin derivatives. The N atom is in a planar configuration. In the crystal, mol­ecules are linked into zigzag layers parallel to (100) by O—H⋯O hydrogen bonds.