DISCOVERY OF NOVEL MACROLIDE ANTIBIOTICS AND METHODOLOGY DEVELOPMENT OF N-SULFINYL METALLODIENAMINES

Abstract

My Ph.D. research consists of two components: discovery of novel macrolide antibiotics and methodology development of N-sulfinyl metallodienamines. To tackle bacterial resistance, new antibiotics are desperately needed. My research objective is to address this need by designing, synthesizing, and evaluating novel macrolide antibiotics based on the best-in-class drug candidate, solithromycin. The drug discovery including following three projects: 1) Synthesis of solithromycin analogs wherein the desosamine sugar has been replaced with an acyclic amino alcohol surrogate; 2) In cellulo Click chemistry wherein the bacterial cell serves as the reaction vessel and the ribosome catalyzes the formation of triazole cycloadducts by testing different combinations of azide and alkyne fragments. One of the mechanisms of resistance to macrolide antibiotics is exemplified by methylation of A2058 by the methyltransferase encoded in erm genes. Methylation or dimethylation of A2058 leads to a steric clash with the macrolides and reduces the affinity of the macrolide for the ribosome. Thus, the bacterial resistant can be relieved via disrupting steric clashes between desosamine and A2058 residues. In 2017, I started a new project looking at the scope of the acyclic domino Michael/Mannich reaction to prepare chiral cyclohexenes developed by a previous group member, Dr. Vijay Chatare. This reaction is highly regioselective and stereoselective. Recent research showed that this reaction could be utilized on acroleins, acrylates and unsaturated ketones. Thus, we applied this useful methodology towards the concise total synthesis of (+)-ibogamine.