Crystal Structure of Elsulfavirine, Complex of its Sodium Salt with 15-Crown-5 and its Active Form

Structure of the non-nucleoside HIV transcriptase inhibitor elsulfavirine and that of its active form VM-1500A are studied by powder XRD. Their molecules in crystals are stabilized by hydrogen bonds of amide and amino groups and by stacking interactions between phenolic groups. The corresponding complex is prepared by the co-crystallization of the elsulfavirine sodium salt and 15-crown-5. The structure of this compound is determined by single-crystal XRD. It is shown that the coordination of the sodium atom with 15-crown-5 prevents the formation of a polymer structure due to weak Na–O bonds and that the molecules of the complex are connected into layers by stacking interactions. The conformational analysis of VM-1500A shows that the most energy profitable conformations are stabilized due to the conjugation between phenolic fragments and the sulfo group.