An enantiomerically pure 4-oxo-α-amino acid derivative

ln the molecule of benzyl 2(S)-[(tert-butoxycarbonyl)amino]-4-oxo-6-phenyl-5(E)-hexenoate, C 24 H 27 NO 5 , the amine NH group does not form intramolecular hydrogen bonds with any of the three carbonyl groups present, even the most favourably positioned one, which would give a six-membered ring. Instead, weak intermolecular hydrogen-bonding interactions occur between the NH and CO groups of the amide units in adjacent molecules, linking them into a chain