Streptorubin B is a member of the prodigiosin family of natural products which are receiving considerable attention from academia as well as the pharmaceutical industry for their novel immunosuppressive and cytotoxic properties. Despite this interest, little effort has been shown toward an asymmetric synthesis of streptorubin B or the relationship between its chirality and biological activity. Progress toward the asymmetric synthesis of streptorubin B and its stereoisomers is herein described.

Alkynyliodonium salts are versatile substrates which have been used to form a variety of heterocycles and other ring systems. The alkylidenecarbenes generated from the addition of soft nucleophiles to alkynyliodonium salts can insert intramolecularly into carbon-hydrogen bonds and typically do so with a high degree of regio- and stereoselectivity. The C ring of streptorubin B was made using this branch of hypervalent iodine chemistry, but this route was later abandoned due to failure of subsequent steps and instability of the products formed.

The challenges involved in forming medium sized rings with ring closing metathesis are beginning to be understood and in many cases have been overcome by conformation constraints. The possibility of using ring closing metathesis to close the bridging ten membered D ring of streptorubin B was explored. However, the enthalpy and entropy barriers for this conversion were determined to be too great to surmount. After other ring closing methods were investigated, a Nozaki-Hiyama-Kishi coupling was found to be successful.