Cp2TiCl in natural product synthesis

The synthesis of complex natural products constitutes one of the most exigent tests to prove the usefulness of a new reagent or catalyst. During the past 10 years, methods based on the Cp 2 TiCl-promoted and/or -catalyzed radical epoxide opening have been used by several authors as the key step for the synthesis of more than 50 natural products and advanced synthons. At first, owing to its selectivity and the extremely mild experimental conditions employed, stoichiometric Cp 2 TiCl was chosen for deoxygenation and reductive epoxide opening on densely functionalized substrates, but during the last 5 years catalytic Cp 2 TiCl has been increasingly employed to achieve radical cyclizations of different epoxyalkenes and epoxyalkynes, affording straightforward strategies for the synthesis of complex natural products. In these fields Cp 2 TiCl-based methods have already largely proved their synthetic usefulness but other Cp 2 TiCl-mediated reactions have as yet been scarcely applied. This review focuses on the increasing scope of applications that employ the Cp 2 TiCl-mediated procedures in the synthesis of natural products. We also present the basic concepts of these methods to facilitate and encourage further synthetic applications.