Preparation of benzannulated spiroketals by gold(III) catalyzed spirocyclization of alkynyl diols

Abstract

The first gold(III)-oxazoline catalysed intramolecular tandem dihydroalkoxylations of alkynyl diols to give benzannulated 5,6-spiroketal products is reported. The results showed that Au(III)-bisoxazoline (BOX) and Au(III)-pyridine-oxazoline complexes are highly efficient catalysts for such spirocyclizations. The mono-and dibenzannulated 5,6-spiroketals were obtained in high yields (> 90%) by rapid conversion of symmetrical and nonsymmetrical alkynyl diols, respectively. The Au(III)-BOX-BF4 catalyst generated minor spirocyclization enantioselectivity (up to 6% ee). The choice of solvent was important for the outcome of the reactions.

Dinuclear silver(I) and gold(I) complexes with chiral oxazoline‐NHC ligands

“…Very recently, Fiksdahl et al became interested in the chemistry gold(III) complexes supported by box and pybox ligands and used in cyclopropanation reactions. [14], [15], [16].…”