Chapter 6 Alkynyliodonium salts in organic synthesis

Abstract

The (almost) unique combination of nucleofugacity and polarizability of the iodide atom has made alkyl (sp 3 ) iodides, particularly, vulnerable to displacement by (polarizable) carbon nucleophiles. Carbon–iodide bond characteristics have been parleyed into a range of transition metal-mediated carbon–carbon bond forming processes utilizing alkenyl- or aryl (sp 2 ) iodides. This chapter discusses the prospects for alkynyl (sp) iodides in carbon–carbon bond forming reactions. The introduction of the more electrophilic alkynyliodonium salts triggered an upsurge in interest in carbon–carbon bond-forming transformations via the (sp)-carbon–I bond. These organoiodine species participate in nucleophilic addition reactions. The chapter also discusses the amine substituents that brought the nitrogen's nucleophilicity within the acceptable range for alkynyliodonium salt addition to be in a position to develop new strategy-level transformations that could be applied to alkaloid synthesis. One implicit benefit of such a strategy is convergency because only the alkynyliodonium salt approach to reactive alkylidenecarbene intermediates permits the introduction of the carbene's substituents from different sources.