Cyclometallated gold(iii) aryl-pyridine complexes as efficient catalysts for three-component synthesis of substituted oxazoles†
Henrik von Wachenfeldt,Alexey V. Polukeev,Nagarajan Loganathan,Filip Paulsen,Philipp Röse,Marion Garreau,Ola F. Wendt,Daniel Strand
Dalton Transactions Pub Date : 02/09/2015 00:00:00 , DOI:10.1039/C4DT03806A
Abstract

Cyclometallated aryl-pyridine gold(III) complexes are shown to be efficient catalysts for the multicomponent reaction between N-benzyl imines, alkynes, and acyl chlorides to form trisubstituted oxazoles. The reaction typically proceeds in good yields (up to over 80%) and short reaction times (∼15 minutes). The high stability of the investigated cyclometallated catalysts enables a retained efficiency for this reaction in terms of rate and yield using as little as 0.5 mol% catalyst, a reduction by an order of magnitude compared to previously used Au(III)–salen complexes. An attractive feature of the present catalytic system is that active catalysts can be formed from simple pre-catalysts under the reaction conditions. Both cyclometallated and non-cyclometallated complexes were characterized in the solid state by single crystal X-ray diffraction.

Graphical abstract: Cyclometallated gold(iii) aryl-pyridine complexes as efficient catalysts for three-component synthesis of substituted oxazoles