The total synthesis of biologically active C-glycoside natural products: 1) Total synthesis of (-)-centrolobine 2) Total synthesis of (-)-varitriol and analogues 3) Progress towards the total synthesis of polyrhacatide A

This dissertation highlights the investigation into the synthesis of C-glycosides and C-furanosides. The first chapter of this dissertation summarizes some of the common synthetic methods used to prepare C-glycosides. The second chapter illustrates the synthesis of the antibiotic natural product (-)-centrolobine. In the synthesis of (-)-centrolobine, the key reaction in the preparation of the beta- C-glycoside intermediate was a nucleophilic addition/reduction sequence to an in situ generated oxocarbenium cation. The third chapter describes the approach to the first total synthesis of the polyketide natural product polyrhacitide A. The key reaction toward the synthesis of polyrhacitide A is a nucleophilic addition/reduction reaction to form the alpha- C-glycoside, and an Evans acetate Aldol reaction in the preparation of the carbon side-chain. The final chapter of this dissertation shows the investigation into the first total synthesis of varitriol. The key reactions in the first total synthesis of varitriol are an achimetric assisted nucleophilic addition reaction to complete the stereochemical makeup of the furanoside subunit, and a cross metathesis reaction to join the two subunits. Using the same strategy, we were able to prepare several varitriol analogues, which are to be investigated for bioactivity.