1. (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.
2. (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.
3. Resolution of 1-n-butyl-3-methyl-3-phospholene 1-oxide with TADDOL derivatives and calcium salts of O,O'-Dibenzoyl-(2R,3R)- or O,O'-di-p-toluoyl-(2R,3R)-tartaric acid
Péter Bagi, András Fekete, Mihály Kállay, Dóra Hessz, Miklós Kubinyi, Tamás Holczbauer, Mátyás Czugler, Elemér Fogassy, György Keglevich Chirality. 2014 Mar;26(3):174-82. doi: 10.1002/chir.22293. Epub 2014 Feb 8.
The resolution methods applying (-)-(4R,5R)-4,5-bis(diphenylhydroxymethyl)-2,2-dimethyldioxolane ("TADDOL"), (-)-(2R,3R)-α,α,α',α'-tetraphenyl-1,4-dioxaspiro[4.5]decan-2,3-dimethanol ("spiro-TADDOL"), as well as the acidic and neutral Ca(2+) salts of (-)-O,O'-dibenzoyl- and (-)-O,O'-di-p-toluoyl-(2R,3R)-tartaric acid were extended for the preparation of 1-n-butyl-3-methyl-3-phospholene 1-oxide in optically active form. In one case, the intermediate diastereomeric complex could be identified by single-crystal X-ray analysis. The absolute P-configuration of the enantiomers of the phospholene oxide was also determined by comparing the experimentally obtained and calculated CD spectra.
