Synthesis of Indenes and Indanes by Gold(I)-Catalyzed Decarbenation

A new gold(I)-catalyzed formal (3+2) cycloaddition reaction between terminal allenes and aryl gold(I) carbenes resulting from cycloheptatriene substrates has been developed. This novel synthetic methodology provides ready access to a variety of highly substituted indenes and  have been applied to construct the tetracyclic core of cycloaurenones and dysiherbols. Another novel synthesis of indanes based on the intramolecular insertion of gold(I) carbenes generated by retro-Buchner into C(sp³)-H bonds has been presented. The mechanism of this new reaction has been studied experimentally and by DFT calculations.