The first structurally characterized three-dimensional pincer-based chiral PC( sp 3 )P dibenzobarrelene scaffold ( 3 and 3′ ) possessing a hemilabile pendant arm was attained by carbo-Diels-Alder cycloaddition process of phosphine precursor and enantiomerically pure bis-(methyl-( S )-lactyl) fumarate in better yield. The pincer compound was chromatographically purified and recrystallized by the slow diffusion method. However, compounds 3 and 3′ are diastereomers and were not isolated individually . The X-ray structures of dibenzobarrelene ( 3 and 3′ ) depict a chiral space group symmetry P 2 1, and the X-ray structure of the free base, with the Flack Parameter of 0.18(6), reveals that structures ( 3 and 3′ ) are non-centrosymmetric and have two different isomers. The molecule contains a tetracyclic carbon chain with a bridged cycle containing two bridgehead carbon atoms and two independent units with almost similar bond lengths and bond angles, which are justified through quantum chemical calculations for 3 and 3 ‵. Hirshfeld surface analysis was performed to quantify the various kinds of interactions. Molecular docking studies demonstrated that the dibenzobarrelene derivative possesses superior binding affinity against both E. coli DNA gyrase B (PDB ID: 4DUH ) and S. aureus gyrase B (PDB ID: 6TTG ) compared to the reference standard, novobiocin, showing potent binding energies of −9.54 kcal/mol and − 10.06 kcal/mol, respectively.
Prasad et al. (Fri,) studied this question.