The development and application of gold(I)-catalyzed cyclizations and rearrangements

Transition-metal catalysis has provided tools necessary for the synthetic organic chemist to synthesize molecules that are difficult to construct under conventional methods. New bonds can be made through creative and unique mechanisms while also providing opportunities to construct optically active molecules.;Catalysis allows chemists to find new avenues for carbon-carbon bond forming reactions which have always been fundamental transformations since the birth of organic chemistry. Two ways to form these bonds are intermolecularly and intramolecularly.;Chapter 1 entails the intermolecular coupling of propargyl alcohols and allylsilanes to give 1,5-enynes using a rhenium-oxo complex. This reaction forms a new carbon-carbon bond under mild conditions without the general precautions of aridity and inert atmosphere. This methodology has also provided a route to the total synthesis of (-)-di-O-Me-Calopin.;Two general intramolecular processes continue to be explored through catalysis: cyclizations and rearrangements. Cyclizations have provided complex carbocycles from relatively simple linear starting materials. In addition, rearrangements form new bonds within a molecule through transposition. Gold(I)-catalysis, with its unique ability to activate alkynes and allenes exclusively in the presence of other unsaturation and heteroatoms, offers a distinctive take on cyclizations and rearrangements.;Chapter 2 describes the use of the 1,5-enynes, synthesized using the methodology from Chapter 1, as linear starting materials in the synthesis of bicyclo-[3.1.0]-hexenes catalyzed by cationic gold(I) complexes. This reaction proceeds stereospecifically with excellent chirality transfer. A tandem cycloisomerization and ring expansion was also implemented.;Chapters 3 and 4 describe the acetylenic oxy-Cope and sila-Cope rearrangements. The oxy-Cope reaction provides dienones, while the sila-Cope gives vinylsilanes. Both transformations offer the opportunity to create functional handles for cross-couplings.;Chapter 5 explains the gold(I)-catalyzed [2+2] cycloaddition of allenenes. This method provides [3.2.0]-exo-methylene bicyclic structures in good yield. When cationic chiral dinuclear gold(I) complexes are implemented, the reaction proceeds with excellent enantioselectivity.;Chapter 6 illustrates the carboalkoxylation of alkynes and subsequent O→C migration of stabilized cations to vinylgold intermediates. An alternative route towards the synthesis of substituted heterocycles is provided.