1. (S)-1-Hydroxy-propan-2-aminium (2R,3R)-3-carb-oxy-2,3-dihydroxy-propanoate monohydrate
Xin-Yu Tang, Xi-Long Yan, Ping Zhang, Ling Qin, Yueguang Yin Acta Crystallogr Sect E Struct Rep Online. 2008 Jan 11;64(Pt 2):o422. doi: 10.1107/S1600536808000391.
The chiral title compound, C(4)H(10)NO(+)·C(4)H(5)O(6) (-)·H(2)O, is a hydrated mol-ecular salt in which the tartaric acid has transferred one proton to the (S)-2-amino-propan-1-ol mol-ecule. The crystal structure is stabilized by a three-dimensional network of N-H⋯O and O-H⋯O hydrogen bonds. The absolute configuration was assigned on the basis of the starting materials.
2. (4S,5S)-2,2-Dimethyl-1,3-dioxolane-4,5-dicarbo-nitrile
Alan H Haines, David L Hughes Acta Crystallogr Sect E Struct Rep Online. 2013 Jun 15;69(Pt 7):o1104. doi: 10.1107/S1600536813015973. eCollection 2013.
The title compound, C7H8N2O2, formed by dehydration of the corresponding dicarboxamide, crystallizes as rectangular prisms. The mol-ecules have a C 2 axis of symmetry through the C atom bearing the methyl groups and the mid-point of the ring C-C bond, and the 1,3-dioxolane ring adopts the extreme twist conformation of the two possible with this symmetry. This brings the two nitrile groups nearest to a linear arrangement when the mol-ecule is viewed along the ring C-C bond. The correct absolute configuration of the mol-ecule was defined by that of the original starting material, (2R,3R)-tartaric acid. The packing is largely controlled by a number of C-H⋯N interactions.
3. (2R,3R)-3-O-Benzoyl-N-benzyl-tartramide
Izabela D Madura, Janusz Zachara, Urszula Bernaś, Halina Hajmowicz, Ludwik Synoradzki Acta Crystallogr Sect E Struct Rep Online. 2012 Jun 1;68(Pt 6):o1891-2. doi: 10.1107/S1600536812022933. Epub 2012 May 26.
The title compound, C(18)H(17)NO(6) [systematic name: (2R,3R)-4-benzyl-amino-2-benzo-yloxy-3-hy-droxy-4-oxobutanoic acid], is the first structurally characterized unsymmetrical monoamide-monoacyl tartaric acid derivative. The mol-ecule shows a staggered conformation around the tartramide Csp(3)-Csp(3) bond with trans-oriented carboxyl and amide groups. The mol-ecular conformation is stabilized by an intra-molecular N-H⋯O hydrogen bond. In the crystal, mol-ecules are linked by O-H⋯O hydrogen bonds between the carboxyl and amide carbonyl groups, forming translational chains along [001]. Further O-H⋯O and N-H⋯O hydrogen bonds as well as weaker C-H⋯O and C-H⋯π inter-molecular inter-actions extend the supra-molecular assembly into a double-layer structure parallel to (100). There are no directional inter-actions between the double layers.
