The complex formation reaction between the l-tartrate (Tar) and calcium ions taking place in neutral and in hyperalkaline (pH > 13) aqueous solutions has been investigated. It was demonstrated that upon NaOH addition the solubility of the CaTar precipitate significantly increases. Conductometric and freezing point depression measurements further confirmed that in this process water soluble species are formed as a result of a reaction between the CaTar and the hydroxide ion (or, conversely, between Ca(OH) and the Tar ion). C NMR spectroscopic measurements yielded the value of pK = 15.4 ± 0.2 for the proton dissociation of one of the alcoholic OH groups of Tar (at 25.0 °C and 4 M Na(Cl) ionic strength). Upon addition of calcium ions to an alkaline Tar solution, the H NMR signal gradually broadened and theC-satellite peaks split to two components, which also indicate complexation. From H/Pt potentiometric titrations performed with solutions in the 13.6 ≤ pH ≤ 14.4 range, it was observed, that this complex formation is accompanied by a hydroxide ion consuming process. The titration curves can be best described via assuming the formation of the CaTarH (lg β = -11.2 ± 0.1) and CaTarH (lg β = -25.3 ± 0.1) complexes. In hyperalkaline solutions, these two species account for more than 90-99% of the calcium ions present and the contribution of the other reasonable and well-established calcium-containing solution species is rather small. The possible structures of the above complexes have been modeled via ab initio calculations. The stoichiometries are consistent both with species containing coordinated alcoholate group(s) and with mixed Ca(ii)-hydroxo-tartrato complexes. From the data available at present, both types of structures can be considered as chemically reasonable.

This work involves the synthesis and subsequent development of a number of novel organocatalysts generated from β-amino acids bearing diendo and diexo norbornene skeletons to improve their catalytic characteristics.

Candida antarctica lipase B-catalyzed hydrolysis of carbocyclic 5–8-membered cis β-amino esters was carried out in green organic media, under solvent-free and ball-milling conditions. In accordance with the high enantioselectivity factor (E > 200) observed in organic media, the preparative-scale resolutions of β-amino esters were performed in tBuOMe at 65 °C. The unreacted β-amino ester enantiomers (1R,2S) and product β-amino acid enantiomers (1S,2R) were obtained with modest to excellent enantiomeric excess (ee) values (ees > 62% and eep > 96%) and in good chemical yields (>25%) in one or two steps. The enantiomers were easily separated by organic solvent/H2O extraction.

The synthesis of alicyclic 2-methylenethiazolo[2,3-b]quinazo­l­inones is performed via base-promoted cascade reactions, starting from either alicyclic β-amino propargylamides using carbon disulfide, or from alicyclic ethyl 2-isothiocyanatocarboxylates by addition of propargylamine. In both cases the cascade reaction proceeds by way of a favoured 5-exo-dig process during the second ring closure, as confirmed by full NMR spectroscopic assignments. Moreover, a high-yielding retro­-Diels–Alder (RDA) reaction is performed on the norbornene derivatives leading to 2-methylene-2H-thiazolo[3,2-a]pyrimidin-5(3H)-ones. The obtained compounds exert modest antiproliferative activities against a panel of human gynaecological cancer cell lines.