NATURAL PRODUCT ANALOGUES AND 2-PYRIDONE PHOTOCHEMISTRY

Abstract

There is a profound need for new antibiotics which overcome bacterial resistance. The predominant source for these is natural products; however, they are often quickly rendered ineffective due to antibiotic resistance. A proven method in drug discovery is improving the properties of natural products through diverted total synthesis (DTS). Of particular interest is promysalin, which is produced by Pseudomonas putida, and selectively inhibits the growth of Gram-negative pathogenic bacteria Pseudomonas aeruginosa at nanomolar concentrations. The work herein describes modifications to the side chain which were shown to modulate antibacterial potency and specificity. A similarly inspired approach to countering antibiotic resistance is the targeted modification of a single carbon to silicon, motivated by the proven success of this substitution shown in pharmaceuticals and amino acids. The target for this modification is albocycline, a known macrolactone antibiotic that exhibits potent antibiotic activity against S. aureus. Replacing the C4 carbon of albocycline with silicon will provide sila-albocycline with enhanced hydrogen bonding properties and altered lipophilicity due to the slight changes from the carbon to silicon atom. In addition, there is anticipated intrinsic stability of the silanol toward rearrangement reactions than carbon-based. The proposed synthesis diverts from the known total synthesis of albocycline, as reported by the Andrade Group. This work details the efforts made towards the total synthesis of sila-albocycline. Lastly, there is untapped potential for UV-promoted photochemistry to create molecular scaffolds, which may lead to novel synthetic routes to complex molecules in addition to providing new polycycles that may expand current medicinal products. The work herein describes the synthesis of tethered chloro- and methoxy-substituted benzyl alcohols to 2-pyridones and the resulting products when exposing the solution to ultraviolet light. This generated new polycycles with complex structures which have unexplored biological or medicinal properties.