Determination of kinetic parameters of enantiomerization of benzothiadiazines by DCXplorer

Benzothiadiazines differently substituted at the sulfonamidic nitrogenatom, at the stereogenic carbon atom and at the anilinic nitrogen atom have been synthesizedand fully characterized. Enantioseparation of these compounds has revealedrapid on-column enantiomerization. The recently developed software DCXplorer hasbeen successfully applied to calculate enantiomerization kinetic parameters. Enantiomerizationbarriers of 3-phenyl substituted benzothiadiazines, calculated in this work, haveindicated a higher enantiomerization rate suggesting that the aromatic substituentexerts a strong effect on the enantiomerization process. Methyl substitution on N2 positionled to higher free energy barriers of enantiomerization, suggesting negative influenceof methyl in the N2 position on enantiomerization kinetics. However, methylationon N4 position increases the enantiomerization rates significantly. The results obtainedhave been employed to postulate an enantiomerization mechanism for chiral benzothiadiazinetype compounds.