Silver‐Free Activation of Ligated Gold(I) Chlorides: The Use of [Me₃NB₁₂Cl₁₁]⁻ as a Weakly Coordinating Anion in Homogeneous Gold Catalysis

Abstract

Phosphane and N-heterocyclic carbene ligated gold(I) chlorides can be effectively activated by Na[Me3NB12Cl11] (1) under silver-free conditions. This activation method with a weakly coordinating closo-dodecaborate anion was shown to be suitable for a large variety of reactions known to be catalyzed by homogeneous gold species, ranging from carbocyclizations to heterocyclizations. Additionally, the capability of 1 in a previously unknown conversion of 5-silyloxy-1,6-allenynes was demonstrated.

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

“…[109] Furthermore,t he oxidation of [B 12 X 12 ] 2À to the corresponding radical monoanions [B 12 X 12 ]C À (where X = F, Cl, Br) and even to the neutral B 12 X 12 (for X = Cl or Br)with potential synthetic interest in introducing these WCAsin oxidative routes-has also been recently demonstrated. [116,117] Furthermore,t he use of the radical species Me 3 N-B 12 Cl 11 C as ap otent oxidant of species with high oxidation potentials has also recently been reported. [113][114][115] Thei ncorporation of the ammonium group reduces the overall charge to À1, thereby reducing lattice enthalpies and improving solubility compared to the parent dianionic [B 12 X 12 ] 2À closo-borates.T heir performance as WCAsh as seen [R 3 N-B 12 X 11 ] À ions employed in the formation of [Ph 3 C] + and [AlEt 2 ] + ions as well as in gold(I) catalysis.…”

Synthesis and Applications of Perfunctionalized Boron Clusters

“…Single crystal X-ray structural data was also obtained which revealed a dimeric active catalyst and the weakly coordinating nature of the dodecaborate counterion. 99 The kinetic stability of these perfuctionalized boron clusters is particularly relevant to (cationic) transition metal catalysis, since even the widely used BAr F anion ([B(C 6 F 5 ) 4 ] − ) has been shown to engage in aryl ring transfer in the presence of transition metal cations. 100,101,102 …”

[1, 2]‐Migration Reactions Catalyzed by Gold Complexes and their Applications in Total Synthesis

“…The silver‐free activation of ligated gold(I) chlorides was also possible when employing the sodium salt of the closo ‐dodecaborate [Me 3 NB 12 Cl 11 ] − as weakly coordinating anion, and the carbocyclization product 11 was formed in good yields (Scheme , Eq. 3) . This cyclization strategy was the key step of the total synthesis of (+)‐cyperolone, although in this particular case platinum(IV)chloride was superior to gold catalysts .…”