The gold(I)‐catalyzed oxidative cyclization of 7‐ethynyl‐1,3,5‐cycloheptatrienes gives 1‐substituted barbaralones in a general manner, which simplifies the access to other fluxional molecules. As an example, we report the shortest syntheses of bullvalene, phenylbullvalene, and disubstituted bullvalenes, and a readily accessible route to complex cage‐type structures by further gold(I)‐catalyzed reactions.

Gold(I) acetylide and σ,π-digold(I) alkyne complexes derived from one prototypical 1,6-enyne and from 7-ethynyl-1,3,5-cycloheptatriene have been prepared and structurally characterized. Their possible role in gold(I)-catalyzed cycloisomerizations has been studied by experiment and by DFT calculations. Gold(I) acetylides are totally unproductive complexes in the absence of Brønsted acids. Similarly, no cyclizations were observed by heating σ,π-digold(I) alkyne digold(I) at least up to 130 °C. Theoretical studies provide a rationale for the much lower reactivity of digold species in reactions of enynes.

The goal of this short review is to provide an overview of the different synthetic methodologies applied along the years for the synthesis of bullvalenes, prototypical fluxional molecules that were key in the understanding of valence tautomerism phenomena. Some interesting applications of these unique shapeshifting compounds are also presented.1 Introduction2 Classical Syntheses of Bullvalenes3 Recent Developments in the Synthesis of Bullvalenes4 Applications of Bullvalenes5 Conclusion

The first total synthesis of repraesentin F has been accomplished by a highly diastereoselective gold(I)-catalyzed cyclization cascade as the key step. This cycloisomerization/Prins-type tandem transformation enabled direct access to the atypical tricyclic carbon skeleton of the natural product with the required syn/ anti/ syn ring fusion. This synthetic effort also allowed reassignment of the relative configuration of repraesentin F and determination of its absolute configuration.