Gold‐Catalyzed Hydrofunctionalizations and Spiroketalizations of Alkynes as Key Steps in Total Synthesis

Abstract

This contribution summarizes the application of homogeneous gold catalysis in hydrofunctionalization and spiroketalization reactions in total synthesis, the most frequent applications of gold catalysis in that sector.

Total Synthesis of Limaol

“…We recognized an opportunity to craft this substructure, which features a double anomeric effect, via π-acid catalysis. 12 , 13 This allows the masked C18-carbonyl group to be encoded as a triple bond, which, in turn, should facilitate the build-up of the carbon skeleton from smaller subunits. The homoallylic alcohol at C27 was deemed another privileged assembly point, given the huge repertoire of known asymmetric allylation reactions.…”

Enantioselective C−H Functionalization Reactions under Gold Catalysis

“…Capitalizing on the unique soft π-acidic nature of gold complexes, [20][21][22] a number of transformations ranging from mono- [23][24][25][26][27] and difunctionalization [28] of CÀ C bonds, enyne cycloisomerization, [29][30][31][32][33][34] diyne cycloisomerization, [35,36] carbene transfer reactions, [37][38][39][40][41][42] etc. have been developed, which are now being routinely executed in the synthesis of simple to complex natural products [43][44][45][46][47] as well as various materials. [48] Yet, accessing efficient methodologies based on gold-catalyzed CÀ H functionalization is still underdeveloped.…”

Gold-Catalyzed Synthesis of Small Rings

“…In 1987, the first homogeneous gold-catalyzed addition of nucleophiles to alkynes was realized by the group of Utimoto using sodium tetrachloroaurate dihydrate. , One decade later, Teles et al and Tanaka et al demonstrated the possibility of activating alkynes using gold­(I) complexes. From that point, the field of gold­(I) catalysis started to gain momentum year after year and still today remains one of the most active areas of research in organometallic chemistry. , This comes as a consequence of the ability of gold­(I) complexes to activate π bonds in a very selective manner. − Its potential, attributed partially to relativistic effects, is illustrated by the wide molecular complexity − that can be built through the gold­(I)-catalyzed cycloisomerization of enynes (Scheme ). − …”