Catalytic Alkyne Functionalization for Use in Organic Synthesis
Transition metals interact with alkynes to form s-alkynyl, p-alkyne and vinylidene complexes that often exist in dynamic equilibrium with one another, while serving as key intermediates in the various transformations in catalytic settings. Our laboratory has been engaged in the development of new methods for alkyne functionalization via mechanisms involving a metal vinylidene as a catalytic intermediate. A diverse array of new reactions has been developed including enyne cycloisomerization, and annulation processes such as hydrative, alkylative, and carboxylative cyclizations. Recently, in a departure from these C-C bond-forming cyclizations, our explorations have been focused on the oxygen-transfer to the metal-bound carbene intermediate. This approach has led to the discovery of catalytic alkyne oxygenation that occurs through the intermediacy of a metalloketene arising from oxygenation of the metal vinylidene. Also investigated has been a tandem addition–cyclization–rearrangement process, where alkynyl hydrazones react with organoboronic acids to give cycloalkene products in a traceless fashion. The cascade reaction is based on merger of pericyclic rearrangement and transition metal mediated catalysis making use of a p-alkyne complex. Discussed in this presentation will be the design, implementation and mechanistic studies of the metal-catalyzed reactions of alkynes for use in organic synthesis.
Hosted by Professor Lawrence Williams
~Coffee/tea will be served prior to the lecture~