Gold-Catalyzed Synthesis of 5 and 6-Membered Rings for the Construction of Molecular Diversity

Identifier:  TDX:2553

Handle: https://hdl.handle.net/20.500.11797/TDX2553

Authors:  Calleja Ramos, Pilar

Abstract:
The research developed in this Doctoral Thesis comprises from the synthesis of polyaromatic compounds to the preparation of various naturally occurring quinonoid compounds (natural product synthesis), highlighting the proficiency of homogeneous gold catalysis for the construction of molecular diversity. On the one hand, a novel approach for the synthesis of a new crushed fullerene C60 by a threefold Pd-catalyzed cross-coupling of four C15 trindene fragments has been developed. The central motif’s trindene C15 skeleton was constructed through a triple gold(I)-catalyzed oxidative cyclization. On the other hand, the scope of the intramolecular gold(I)-catalyzed [2+2+2] cycloaddition reaction was extended to O-protected homopropargylic and allylic oxo-1,5-enynes. Under the optimized reaction conditions, the cyclization takes place with moderate to excellent yields (38–90%) and increased selectivity in most of the cases, providing access to substituted octahydro-1H-indenes. Concerning the use of gold catalysis for the synthesis of natural products, we have developed an enantioselective gold(I)-catalyzed enyne alkoxycyclization, which can be applied for the construction of the carexanes core skeleton. Additionally, the intramolecular gold(I)-catalyzed [4+2] cycloaddition reaction has been used for the construction of the 6,6,5-tricyclic skeleton of the pycnanthuquinones, another family of alkaloids. Finally, a detailed examination of gold(I)-catalyzed skeletal rearrangements of model 1,6-enynes bearing OR groups at the propargyl position, which are prone to undergo intramolecular 1,5-migration in the absence of external nucleophiles, was performed.