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A comparative study of the kinetic resolution (KR) of racemic 6-substituted 2-methyl-1,2,3,4-tetrahydroquinolines with acyl chlorides of (S)-naproxen, N-phthaloyl-(S)-leucine, and (R)-O-phenyllactic acid was carried out. The selectivity factors in the KR of racemic amines with acyl chlorides of (S)-naproxen and (R)-O-phenyllactic acid were shown to be approximately the same and higher than those for the KR of N-phthaloyl-(S)-leucyl chloride. The reasons for the stereodifferentiation in the KR of racemic tetrahydroquinaldines containing groups of different electronic properties by acyl chlorides of three different chiral acids were explained using the DFT method. The conditions for stabilizing π—π interactions of aromatic fragments of the reagents, which do not occur in the same form in the transition state and lead to the minor diastereoisomeric product, are created in the transition state of the faster acylation reaction with (S)-naproxen and (R)-O-phenyllactic acyl chlorides. In the case of the KR of 2-methyl-1,2,3,4-tetrahydroquinoline and 2-methyl-6-methoxy-1,2,3,4-tetrahydroquinoline with N-phthaloyl-(S)-leucyl chloride, the acylation diastereoselectivity is determined, most likely, by conformational factors. The individual (S)-enantiomer of 2-methyl-6-methoxy-1,2,3,4-tetrahydroquinoline of high optical purity was synthesized using the KR of the racemate with (S)-naproxen acyl chloride.

The possibility for separating enantiomers of a number of practically significant 2-aryloxycarboxylic acids was studied by normal- and reversed-phase HPLC on popular chiral stationary phases. The best separation parameters were achieved on the chiral phases with the polysaccharide base Chiralcel OD-H and Chiralpack AD under the normal-phase HPLC conditions. The (S)- and (R)-enantiomers of 2-(1-naphthyloxy)- and 2-(2-iodophenoxy)propionic acids with enantiomeric excess ee >99% were isolated using preparative chiral HPLC.

The deboronation of enantiomers of planar-chiral benzyl (3-formamido-1,2-dicarba-closo-dodecaboran-1-yl)acetate gave the individual (RP)- and (SP)-enantiomers (ee > 98%) of a new amino acid containing a nido-carborane fragment, (3-ammonio-7,8-dicarba-nido-undecaboran-7-yl)acetic acid. Chiral HPLC methods for the analysis of enantiomeric purity of this compound was developed.

A comparative study of the kinetic resolution of racemic derivatives of 3,4-dihydro-3-methyl-2H-[1,4]benzoxazine using racemic 2-aryloxypropionyl chlorides was performed. It was found that the acylation of racemic amines with racemic 2-(1-naphthyloxy)propionyl chloride leads to amides enriched with (3R*,2′R*)-diastereomers, while the acylation with 2-phenoxypropionyl chloride gives predominantly (3R*,2′S*)-amides. Quantum chemical modeling of the process of kinetic resolution at the COSMO-CH2Cl2-B3LYP-D3-gCP/def2-TZVP//B3LYP-D3-gCP/def2-SVP level of theory was performed. The computational results are in a good agreement with the experimental data.

A comparative study of the kinetic resolution of racemic 3-tert-butyl-3,4-dihydro-2H-[1,4]-benzoxazine through the acylation by various chiral acyl chlorides was carried out. A preparative method for obtaining enantiomerically pure (S)-3-tert-butyl-3,4-dihydro-2H-[1,4]benzoxazine can be based on the acylation with N-phthaloyl-(S)-phenylalanyl or (R)-2-phenoxypropionyl chlorides, followed by the acid hydrolysis of the corresponding diastereomerically pure amides.

Reversed-phase HPLC on chiral stationary phases was used to study the influence of the structure of purine and 2-aminopurine conjugates with chiral heterocyclic amines on the retention times. The optimum conditions for separation of enantiomers were found. The best parameters of separation of stereoisomers of all the compounds examined were achieved on a (S,S)-Whelk-O1 column in weakly alkaline aqueous methanol systems.

New strains of Rhodococcus erythropolis 25 and Microbacterium paraoxydans 20-11c actinobacteria were used to obtain (S)-7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine (99.6% ee) by enantioselective microbial hydrolysis of the corresponding racemic N-acetyl derivative.

Kinetic resolution of racemic 3-methyl-2,3-dihydro-4H-[1,4]benzoxazines in the reaction with chiral 2-arylpropionyl chloride predominantly yielded R*,R*-diastereomers. Ibuprofen acyl chloride as acylating agent was found to be more selective and sensitive to the changes in the reaction temperature as compared to naproxen acyl chloride and 2-phenylpropionyl chloride.

The comparative X-ray diffraction study of racemic and (S)-enantiomer of 7,8-difluoro-3-methyl-2,3-dihydro-4H-[1,4]benzoxazine was carried out. The both forms of benzoxazine are crystallized in the orthorhombic crystal system, the (S)-enantiomer is crystallized in the chiral space group P212121, while the racemate is crystallized in the centrosymmetric Pbca space group. The bond lengths and bond and torsional angles in the both molecules are almost equal. The packing of the racemate is characterized by a closer interaction of polar NH…O groups.

New routes to closo-carboranyl derivatives of L-lysine and L-glutamic acid with free gA-NH2 groups were proposed.

A determination of enantiomeric purity of 1-substituted (Me, Ph, and Pri) 3-amino-1,2dicarba-closo-dodecaboranes by HPLC on chiral Chiralcel OD-H and Chiralpac AD stationary phases involving preliminary phthaloylation of 3-aminocarboranes has been suggested as a general method.

The reaction of 3-phenyl-1,2,4-triazin-5(4H)-one (1) with l-menthol in the presence of aliphatic acid anhydrides results in (6S)- and (6R)-1-acyl-6-(l-menth-3-yl)-1,6-dyhydro-3-phenyl-1,2,4-triazin-5(4H)-ones. The reaction is diastereoselective with predominant formation of (6S)-isomers. The reaction diastereoselectivity increases with enhancement of the steric hindrance in the vicinity of the reaction center of the azine.