BOC-PHE-AMINOMALONALDEHYDE

The crystal structure of the title compound, (N-tert-butoxycarbonylphe nylalanyl) aminomalonaldehyde {tert-butyl ylmethylaminocarbonyl)-2-phe nyl-1-ethyl]carbamate, C17H22N2O5}, was determined in order to examine the aminomalonaldehyde group in a peptide chain. The planarity constr aints of the peptide bond and the aminomalonaldehyde group result in t he formation of a pseudo-seven-membered ring through one intramolecula r hydrogen bond (O17--H17 ... O11). The bond lengths in this ring indi cate delocalization of the pi electrons and the formation of a weak co njugated pi-electron system.