SYNTHESIS OF PHARMACOLOGICALLY ACTIVE MOLECULES THROUGH BIOCATALYTIC APPROACHES: STUDY OF THEIR STEREOCHEMISTRY AND POLYMORPHISM BY MEANS OF SPECTROSCOPIC AND CRYSTALLOGRAPHIC METHODS.

Elagolix is the first non-peptide orally active gonadotropin-releasing hormone (GnRH) antagonist, approved for the treatment of sex hormone-dependent diseases, such as endometriosis and uterine fibroids. This PhD project was focused on this drug, studying its conformational features, and improving the synthetic procedures found in the literature. Firstly, theoretical experiments revealed that this drug exists in solution as a mixture of two atropisomers, which belong to class 2 due to an estimated interconversion rotational barrier of 22.3 kcal/mol. This finding could help to face the great challenges in the drug discovery and development of this class of compounds, caused by the conformational instability. In addition, the deepen spectroscopic investigations performed on elagolix and its intermediates allowed for the complete assignment and interpretation of the 1H, 13C, and 15N NMR signals, filling the existing gap in the literature. Chart 1. The two atropisomeric forms of elagolix sodium salt. Because the individual atropisomers of a given molecule may differ considerably in their pharmacological properties, we designed and synthesized a new series of elagolix analogues, differently substituted at the 4- or 6-position of the uracil moiety, with the aim of studying the impact of these modifications on atropisomeric properties. Three of the newly obtained compounds have a higher rotational barrier than elagolix, allowing the separation and characterization of their single atropisomers by means of different analytical techniques. Moreover, since our study on the already disclosed 21-bromoderivative of elagolix resulted in the identification of two thermally stable atropisomers, this compound was selected for the development of a new enzymatic approach for the atropisomers separation. For the new compounds and their single atropisomers, biological tests are currently underway on HEK-293 cells expressing the human GnRH receptor (hGnRH1R) to verify the good receptor affinity predicted by the molecular dynamics simulations.