Gold- or Platinum-Catalyzed Cascade Processes of Alkynol Derivatives Involving Hydroalkoxylation Reactions Followed by Prins-Type Cyclizations

An efficient method for the synthesis of [3.3.1]bicyclic compounds from easily available alkynol derivatives has been developed. The reaction is based on a gold‐ or platinum‐catalyzed tandem process that involves an intramolecular hydroalkoxylation of a triple bond followed by a Prins‐type cyclization. The reaction has been carried out with differently substituted alkynol derivatives and oxygen‐, nitrogen‐, and carbon‐centered nucleophiles. The incorporation of halogen atoms as nucleophiles and elimination reactions has also been studied. Enantiomerically pure [3.3.1]bicyclic systems were easily synthesized from the chiral pool. A circular route: Functionalized [3.3.1]bicyclic systems are obtained from simple allyl‐substituted 5‐hexyn‐1‐ol derivatives and different nucleophiles in a very simple fashion (see scheme; Nu=nucleophile). A catalytic cascade reaction is carried out that involves a 6‐exo‐cycloisomerization reaction followed by a Prins‐type cyclization.