Preparation of optically active cis-4-methylcyclohex-4-ene-1,2-dicarboximides by a combination of Diels–Alder reaction and complexation with optically active hosts and enantioselective Diels–Alder reaction in inclusion crystals in a water suspension medium

Optically active Diels–Alder adducts were prepared using a one-pot preparative method and enantioselective Diels–Alder reaction with optically active hosts in a water suspension medium

Formation of racemic compound crystals by mixing of two enantiomeric crystals in the solid state. Liquid transport of molecules from crystal to crystal

Mixing of powdered (-)- and (+)-enantiomer crystals in the solid state gives crystals of the racemic compound. This racemic crystal formation was followed by IR spectral measurement of a 1 :1 mixture of (-)- and (+)-enantiomer crystals as a Nujol mull. As the formation of racemic crystals proceeds, the OH absorptions of the enantiomer disappear gradually and new OH absorptions due to the racemic compound appear. The formation of racemic crystals from enantiomer crystals has been studied for various kinds of chiral compounds: 2,29-dihydroxy-1,19-binaphthyl (1) and its derivatives, 10,109-dihydroxy-9,99-biphenanthryl (4), 2,29-dihydroxy-4,49,6,69-tetramethylbiphenyl (5) and its derivatives, 4,49-dihydroxy-2,29,3,39,6,69- hexamethylbiphenyl (8), 1,6-di(o-chlorophenyl)-1,6-diphenylhexa-2,4-diyne-1,6-diol (11) and its derivatives, trans-4,5-bis[hydroxy(diphenyl)methyl]-2,2-dimethyl-1,3-dioxacyclopentane (17) and itsderivatives, tartaric acid (20) dimethyl tartrate (21), malic acid (22), mandelic acid (23), and norephedrine (24). These molecular movements and blending occur rapidly in the presence of liquids such as liquid paraffin (Nujol), seed oils such as olive, coconut, rapeseed and soybean oil, artificial oil such as silicone oil and water, although the same movement also occurs in the absence of the liquid. For example, keeping a mixture of powdered (-)-1 (1a) and (+)-1 (1b) at room temperature for 48 h gives racemic crystals (1c). However, molecular aggregation sometimes occurs in solution but not in the solid state. Forexample, recrystallization of (-)-16 (16a) and (+)-16 (16b) from solvent gives racemic crystals of 16c, although mixing of these two components as powders in the presence of liquid does not give 16c. In order to determine the mechanism of the molecular movement in the solid state, X-ray crystal structures of optically active and racemic compounds and also the molecular movements from optically active crystal to racemic crystal have been studied

Crystal structure of N-isopropyl-N-(phenyl)phenylglyoxylamide

The title compound [systematic name: 2-oxo-N,2-diphenyl-N-(propan-2-yl)acetamide], C17H17NO2, was synthesized and its photoreactive properties in the crystalline state were investigated. In the molecule, the carbonyl group attached to the phenyl ring adopts an s-trans configuration with respect to the isopropyl group. Moreover, the distance between the C atom of the carbonyl group and the N-bound C atom of the isopropyl group is 3.845 (2) Å, which is much longer than 3.2 Å, the threshold for photoreactions to take place in the molecule. As a result, the crystal did not photoreact upon UV light irradiation. In the crystal, the molecules are linked via weak intermolecular C—H...O hydrogen bonds, forming a layer structure parallel to the ab plane