Protection of the Gold(I) Catalyst by AsPh₃ in Reactions of Enynes

Abstract

Neutral gold complexes with hydrogen-bond-supported heterocyclic carbene (HBHC) and nitrogen acyclic carbene (NAC) ligands have been synthesized by the reactions of isocyanogold derivatives [AuCl(CNR)] with amines. Cationic [Au(carbene)(AsPh 3 )][SbF 6 ] complexes have also been prepared. The catalytic activity of both types of complex (for the former, AgSbF 6 is used to extract the halide ligand) in the skeletal rearrangement and methoxycyclization of enynes has been studied. The cationic complexes with AsPh 3 are[a]

Versatile synthesis of cationic N-heterocyclic carbene–gold(i) complexes containing a second ancillary ligand. Design of heterobimetallic ruthenium–gold anticancer agents

“…by one pot reaction of gold precursors [(carbene)AuCl] and AgSBF 6 /AsPh 3 (2–5 h reactions). 17 Cationic gold(I) compounds of the type [(NHC)Au(α-diimine)]X (X = BF 4 − , SbF 6 − ) have also been reported by Braunstein et al . by one pot reaction of [(NHC)AuCl]/α-diimine and TlPF 6 or AgX (24 h reaction).…”

“…The beneficial effects of a second ligand in processes catalyzed by gold(I)-N-heterocyclic compounds have been described. 17 Cationic gold(I) N-heterocyclic carbene complexes containing phosphanes of the type [(NHC)AuPR 3 ]I (NHC = 1,3-diethylbenzimidazol-2-ylidene) have been described recently by Ott et al . as very efficient enzyme inhibitors with promising potential as anticancer chemotherapeutics.…”

“…The beneficial effects of a second ligand in processes catalyzed by gold(I)-Nheterocyclic compounds have been described. 17 Cationic gold(I)-Nheterocyclic carbene complexes containing phosphanes of the type [(NHC)AuPR 3 ]I (NHC = 1,3-diethylbenzimidazol-2-ylidene) have been described recently by Ott et al as very efficient enzyme inhibitors with promising potential as anticancer chemotherapeutics. 18,19 The preparation of these complexes involves the addition of NaCO 3 to N-heterocyclic imidazolium iodide at 50 1C followed by addition of the corresponding chlorido(phosphane) gold(I) derivatives with reaction times ranging from 8 to 60 hours, and subsequent purification by extraction in CH 2 Cl 2 /H 2 O.…”

“…Gold(I) compounds with hydrogen-bond-supported heterocyclic carbene (HBHC) and nitrogen acyclic carbene (NAC) of the type [(carbene)Au(AsPh 3 )][SbF 6 ] have been described by Espinet et al by one pot reaction of gold precursors [(carbene)-AuCl] and AgSBF 6 /AsPh 3 (2-5 h reactions). 17 For different synthetic/catalytic purposes it may be relevant to separate AgCl formed in the abstraction reaction before addition of the second ancillary ligand. We have demonstrated that the use of a silver salt containing an anion that can be covalently coordinated to gold allows for the separation of solutions (after filtration of AgCl) containing in situ generated [(NHC)AuOClO 3 ] species that are stable for at least 72 h at 5 1C, and for 2 hours at RT.…”

The chemistry of the carbon-transition metal double and triple bond: Annual survey covering the year 2014

“…Gold cycloisomerization catalysts were activated through Lewis acid complexation [1174] and poisoned gold cycloisomerization catalysts were successfully re-activated through treatment with protic or Lewis acids [1175]. Use of triphenylarsine as a ligand additive allowed for a significant catalyst load M a n u s c r i p t 149 reduction for various enyne cycloisomerization processes [1176]. The carbocation stabilizing ability of a phosphine-gold fragment was estimated to be better than that of a methyl or phenyl group and similar to a cyclopropyl group based on the analysis of structural effects for cyclopropylcarbene gold complexes, a commonly proposed intermediate in many of these transformations [1177].…”