Structure of a peptide oxazolone: 2-(1'-benzyloxycarbonylamino-1'-methylethyl)-4,4-dimethyl-5-oxazolone

Abstract

C₁₆H₂₀N₂0₄, monoclinic, P2₁, a = 6.270 (1), b= 11.119(3), c= 11.640(4)Å, β= 100.7 (2)°, D_m = 1.27 (flotation), D_c = 1.26 Mg m^-3, Z = 2. The structure has been refined to a final R value of 0.041 for 1584 independent counter-measured reflections. The oxazolone ring in the molecule is nearly planar. The exocyclic O atom is 0.065 Å out of the plane defined by the other four atoms in the ring belonging to the lactone group. The difference in length between the two adjacent C-O bonds in the ring is small, but significant. The crystal structure is stabilized by van der Waals interactions and a N-H···N hydrogen bond.