New Gold-Catalyzed Reactions and Applications for the Synthesis of Alkaloids (bookzcity)

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Gold chemistry has attracted increasing attention in recent years in the realm of
homogeneous catalysis. In particular, gold complexes have been found to be the
most powerful catalysts for electrophilic activation of alkynes toward a variety of
nucleophiles under homogeneous conditions. Moreover, allenes and alkenes can
also be effectively activated by gold complexes. Our group at the Institute of
Chemical Research of Catalonia (ICIQ) has developed new gold-based methodologies
for the formation of carbon–carbon bonds based on the attack of different
nucleophiles like alkenes, arenes, and electron-rich heteroarenes to alkynes. It has
been the purpose of this Ph.D. thesis to discover new gold-catalyzed transformations
of alkynes and to develop new transformations for the ready build up of
molecular diversity and complexity, in particular in the selective formation of
tricyclic compounds, dihydropyrans, 1,3-dienes, and cyclobutenes. Furthermore, an
approach for the synthesis of the tetracyclic core of the lundurines has been
developed by using a gold-catalyzed cyclization reaction as the key step. The
lundurines are a new type of indoles alkaloids, characterized by an unusually
complex architecture with a cyclopropane fragment embedded within a hexacyclic
ring system that includes a 1H–azocine[5,4–b]indole ring. Interestingly, lundurines
B and D have shown significant in vitro cytotoxicity toward B16 melanoma cells.
This work is an important contribution in the development of new synthetic
methodology using gold catalysts. The synthesis of the tetracyclic core of the
lundurines is a major step toward the achievement of an efficient total synthesis of
this class of antitumor compounds.