2015 Theses Doctoral

Strategies, Tactics, and Tools to Achieve Chemical Syntheses of cis-Clerodane Terpenoids

Ye, Qinda

The clerodane diterpenoids are a large group of secondary metabolites that display an array of biological activities and structural diversity. This dissertation details our efforts to synthesize clerodane natural products through a unified design and the use of a key synthetic intermediate. Thus, Chapter 1 will serve to introduce this unique and interesting class of terpenoids, beginning with their proposed biosynthesis. This section will be followed by a highlight of their diverse biological activities. Lastly, a select collection of representative total syntheses will be described to provide a sense of the state of the art in accessing their molecular complexity. Next, Chapter 2 will begin with our design of a two-phase approach towards the clerodane family, followed by an introduction of scaparvin A as an excellent example of a target with complex architecture and multiple oxygenated functional groups worthy of synthetic and biological study. In addtion, a detailed retrosynthetic analysis of scaparvin A will be described based on our global strategy for accessing the family. Then, we will focus our discussion in Chapter 3 on the efficient construction of the common intermediate, while two modes of directed C–H oxidation to deliver the requisite oxidation state will be covered in Chapter 4. Finally, efforts of late-stage modification towards scaparvin A and related compounds will be summarized in Chapter 5, culminating in a near complete synthesis of scaparvin A as well as a completed total synthesis of scaparvin C.