title: Five- and six-membered ring opening of pyroglutamic diketopiperazine.
abstract: A variety of ring-opening reactions of pyroglutamic diketopiperazine at both the five-membered and six-membered rings is described. Mild, basic conditions facilitate nucleophilic attack by amines at the diketopiperazine carbonyls giving pyroglutamides in excellent yield. Reaction with nucleophiles under acidic conditions give bis-glutamate derivatives of 2,5-diketopiperazine (DKP). These reactions provide simple, two-step sequences to pyroglutamides and symmetrical diketopiperazines from commercial pyroglutamic acid with control of product dictated by reaction conditions, catalyst, and nucleophile.
authors.affiliation: School of Polymers and High Performance Materials, The University of Southern Mississippi, Hattiesburg, Mississippi 39406-0076, USA.
authors.forename: Dennis A
authors.initials: DA
authors.lastname: Parrish
authors.forename: Lon J
authors.initials: LJ
authors.lastname: Mathias
mesh_terms: D000588:Amines / Q000737:chemistry; D002384:Catalysis; D018360:Crystallography, X-Ray; D003500:Cyclization; D054659:Diketopiperazines; D004563:Electrochemistry / Q000379:methods; D018698:Glutamic Acid / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010879:Piperazines / Q000737:chemistry*; D011761:Pyrrolidonecarboxylic Acid / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000588:Amines; D054659:Diketopiperazines; D010879:Piperazines; D018698:Glutamic Acid; D011761:Pyrrolidonecarboxylic Acid