Alkyne dicobalt complexes in carbohydrates: Synthetic applications

Abstract The complexation of alkynes to form dicobalt hexacarbonyl derivatives facilitates the formation, under acid catalysis, of highly stabilized propargylic cations whose reaction with nucleophiles to form propargylic compounds, currently known as the Nicholas reaction, has found ample use in organic synthesis. This transformation has shown to be particularly useful when applied to carbohydrate derivatives. In this chapter, we provide a brief overview on this subject pioneered by early contributions from Isobe’s research group. Thus, carbohydrate-derived dicobalt hexacarbonyl complexes have been used in the epimerization of C-alkynyl glycosides, pyranose ring-opening nucleophile trapping reactions, pyranose ring-opening ring-recyclization leading to medium-sized oxacycles, glycosylation strategies, C-glycosylation, and pyranose to carbocycle transformations, among others. Finally, contributions from our research group focusing on the synthetic applications of Ferrier-Nicholas cations are also presented.