title: A pipecolic acid (Pip)-containing dipeptide, Boc-D-Ala-L-Pip-NH(i)Pr.
abstract: The title dipeptide, 1-(tert-butoxycarbonyl-D-alanyl)-N-isopropyl-L-pipecolamide or Boc-D-Ala-L-Pip-NH(i)Pr (H-Pip-OH is pipecolic acid or piperidine-2-carboxylic acid), C(17)H(31)N(3)O(4), with a D-L heterochiral sequence, adopts a type II' beta-turn conformation, with all-trans amide functions, where the C-terminal amide NH group interacts with the Boc carbonyl O atom to form a classical i+3 --> i intramolecular hydrogen bond. The C(alpha) substituent takes an axial position [H(alpha) (Pip) equatorial] and the trans pipecolamide function is nearly planar.
authors.affiliation: Laboratoire de Cristallographie et Modélisation des Matériaux Minéraux et Biologiques (LCM3B), UMR nth 7036, Groupe Biocristallographie, Université Henri Poincaré, Nancy I, Faculté des Sciences, BP 239, 54506 Vandoeuvre lès Nancy Cedex, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Didierjean
authors.forename: Guy
authors.initials: G
authors.lastname: Boussard
authors.forename: André
authors.initials: A
authors.lastname: Aubry