Direct approaches toward natural product synthesis

In this dissertation, we have explored direct routes to several biologically active natural products.;Chapter 1 describes a novel way to prepare benzoxepin core using a ring-closing metathesis reaction. Bauhiniastatins, which are reported to possess anti-cancer activities and contain benzoxepin skeleton, can thus be synthesized using this methodology.;Chapter 2 illustrates a short synthesis of bauhinoxepin J, which entails use of an environmentally benign radical reaction. This innovative intramolecular radical cyclization opens new avenues for constructing natural products with embeded quinone subunit. Chapter 3 depicts a direct route for the synthesis of aurones and benzophenones, which makes use of 1,3-benzodioxin-4-ones as the key intermediate. This strategy led to successful synthesis of three natural products in a straightforward fashion