[reaction: see text] A new method of achieving homogeneity of chirality via purification of nonracemic (partially resolved) amino alcohols 1a-d and the C2 chiral diamine 2 to obtain samples of higher ee, through preparation of homochiral and heterochiral aggregates using oxalic and fumaric acids, is described.

Simple, convenient methods have been developed using readily available, easy-to-handle reagents to access a variety of chiral amino alcohols and amines, which have considerable potential for applications in asymmetric organic transformations. Scholars from this laboratory in India have made significant contributions to this field, which is the subject of the current review.

Efficient use of the readily accessible chiral C 2 -symmetric acyclic diamines (1-2) as well as macrocyclic amines (3-5) containing trans-1,2-diaminocyclohexyl moiety as chiral solvating agents (CSA) for the determination of enantiomeric excess of representative carboxylic acids (6-7) and an amino acid derivative (8) is illustrated. The enantiomeric composition of different carboxylic acids estimated here by the 1 H NMR method, based on the integration of the corresponding methine proton signals are in good correlation with that determined using HPLC method. The data are in accordance with the formation of multimolecular diastereomeric complexes in solution, which render good splitting of NMR signals for the enantiomers of representative carboxylic acids as well as for N-Ts-phenylglycine (up to ΔΔδ = 0⋅295 ppm, 118 Hz).

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A synthesis of trans-1,2-diaminocyclohexane derivatives via opening of cyclohexene oxide with secondary amines followed by preparation and opening of the corresponding aziridinium ions in situ by primary and secondary amines is described. Use of chiral α-methylbenzylamine for the opening of aziridinium ions gave a mixure of diastereomers that are readily separated by column chromatography. The C 2 symmetric trans-1,2-bis (N-pyrrolidino)cyclohexane was resolved to obtain nonracemic samples that can be readily enriched by co-crystallization with fumaric acid to obtain enantiomerically pure compounds.