In order to predict the general activity pattern of π-acids, we have designed a substrate containing a 7-alkynyl cycloheptatriene moiety, which reacts either as an enyne to give indene products, or as an aryl-allene to give hydroarylation products. The selectivity is actually governed by the softness or hardness of the Lewis or Brønsted acid catalyst used. For instance, whereas soft π-Lewis acids, such as Au, Pt, Ga or In complexes, trigger a nonclassical carbocation rearrangement to generate one product, harder ones incorporating Ag or Cu salts rather give a hydroarylation product. The formation of a dihydroarylation product can also be observed with even harder π-acids or protons. This tool also allows to distinguish between two metals when a two-component catalytic mixture is used, or if adventitious protons compete as the true catalyst.

Revealing the activity of π-acid catalysts using a 7-alkynyl cycloheptatriene

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.