The conformationally chiral 10-nitro-phenanthren-9-yl phenyl sulfide is found to crystallise as one racemic phase and one chiral phase; the chiral phase undergoes total spontaneous resolution on crystallisation.
In search for new examples of absolute asymmetric synthesis (AAS), chiral α‐substituted benzyllithium complexes have been prepared. While [Li(phet)(pmdta)] (1) (phet = 1‐phenylethyl, pmdta = N,N,N′,N″,N″‐pentamethyldiethylenetriamine) affords only racemic crystals, a promising candidate for AAS was indeed found: [Li(phet)(tmpda)], α‐2, (tmpda = N,N,N′,N′‐tetramethylpropylenediamine) crystallises as a conglomerate. Although concomitant polymorphism was not observed, a racemic phase (β‐2) could also be isolated. Chiral crystals of α‐2 gave 2‐phenylpropionic acid in high yield on reaction with gaseous CO2, but the bulk product was racemic. It is unclear whether the lack of selectivity originates during crystallisation or carbonation. In order to investigate this, similar complexes displaying Si or S atoms in the α‐position were prepared and structurally characterized: [Li(tmsb)(tmpda)] (tmsb = 1‐trimetylsilylbenzyl) (3), [Li{C(CH3)(Ph)(SPh)}(pmdta)] (4), [Li{C(CH3)(Ph)(SPh)}(tmeda)] (5), and [Li(tmeda)2][C(CH3)(Ph)(SPh)] (6). The introduction of heavy atoms should allow determination of absolute configuration and enantiopurity, but so far only racemic crystals have been obtained.
2-[(2-Ammonioethyl)amino]acetate dihydrate, better known as N-(2-aminoethyl)glycine dihydrate, C(4)H(10)N(2)O(2) x 2 H(2)O, (I), crystallizes as a three-dimensional hydrogen-bonded network. Amino acid molecules form layers in the ac plane separated by layers of water molecules, which form a hydrogen-bonded two-dimensional net composed of fused six-membered rings having boat conformations. The crystal structure of the corresponding hydroiodide salt, namely 2-[(2-ammonioethyl)ammonio]acetate iodide, C(4)H(11)N(2)O(2)(+) x I(-), (II), has also been determined. The structure of (II) does not accommodate any solvent water molecules, and displays stacks of amino acid molecules parallel to the a axis, with iodide ions located in channels, resulting in an overall three-dimensional hydrogen-bonded network structure. N-(2-Aminoethyl)glycine is a molecule of considerable biological interest, since its polyamide derivative forms the backbone in the DNA mimic peptide nucleic acid (PNA).
The title compound, [CuCl2(C6H7NO)2], was synthesized during a study of conformationally chiral square-planar coordination compounds. The coordination geometry deviates from the square-planar geometry generally adopted by copper(II) chloride complexes with pyridine ligands towards a tetrahedral arrangement of ligands. The complex is conformationally chiral but crystallizes in a centrosymmetric space group with both enantiomers present in the unit cell.
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