title: Cyclo-(-l-prolyl-l-valinyl-) from Burkholderia thailandensis MSMB43.
abstract: THE TITLE COMPOUND [SYSTEMATIC NAME: (3S,8aS)-3-isopropyl-hexa-hydro-pyrrolo-[1,2-a]pyrazine-1,4-dione], C(10)H(16)N(2)O(2),, is a newly isolated cyclic dipeptide from Burkholderia thailandensis MSMB43. There are two independent mol-ecules in the asymmetric unit. Two C atoms and their attached H atoms in the five-membered ring of one of the mol-ecules are disordered over two sets of sites in a 0.715 (5):0.285 (5) ratio. The two independent mol-ecules have the same configuration and the absolute configurations of the chiral centers were determined based on the observation of anomalous dispersion. In the crystal, two types of N-H⋯O hydrogen bonds link pairs of independent mol-ecules.
authors.affiliation: Department of Biological Sciences, Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, PO Box 413, Milwaukee, WI 53201,  USA.
authors.forename: Xiang-Yang
authors.initials: XY
authors.lastname: Liu
authors.forename: Cheng
authors.initials: C
authors.lastname: Wang
authors.forename: Yi-Qiang
authors.initials: YQ
authors.lastname: Cheng