Utilisation of chiral enaminones and azomethine imines in the synthesis of functionalised pyrazoles

Chiral enaminones, derived from commercially available enantipure starting materials, such as (+)-camphor and alpha-amino acids, were employed in cycloconcensation reactions with hydrazine derivatives to afford the corresponding pyrazoles, functionalised with terpene, alanine, 2-phenylethylamine, and beta-amino alcohol moiety. On the other hand, recent study on stereocontrol in cycloadditions of racemic (1Z, 4R*, 5R*)-1-arylmethylidene-4-benzoylamino-5-phenylpyrazolidin- 3-one-1-azomethine imines, available in three steps from hippuric acid, showed, that stereodirecting phenyl group, as well as ortho-substituents at the aromatic ring, control the selectivity of these cycloadditions. In extension, these results are now applied in a study, which is oriented towards combinatorial synthesis of pyrazolo[1,2-a] pyrazolone type of peptidomimetics with variable, yet predictable configuration.