(3S,3'S,5S,5'S,6R,6'R)3,3'-[[(Phenylmethyl)imino]bis[(3S)-3-hydroxy-4,1-butanediyl]]bis[2-oxo-5,6-diphenyl-4-morpholinecarboxylic Acid Bis(tert-butyl) Ester is an intermediate in the preparation of (5S,5’S)-Dihydroxy Lysinonorleucine (D452900), a collagen reducible crosslink agent.