Mechanism of the Transmetalation of Organosilanes to Gold

Abstract

Density functional theory (DFT) calculations were carried out to study the reaction mechanism of the first transmetalation of organosilanes to gold as a cheap fluoride‐free process. The versatile gold(I) complex [Au(OH)(IPr)] permits very straightforward access to a series of aryl‐, vinyl‐, and alkylgold silanolates by reaction with the appropriate silane reagent. These silanolate compounds are key intermediates in a fluoride‐free process that results in the net transmetalation of organosilanes to gold, rather than the classic activation of silanes as silicates using external fluoride sources. However, here we propose that the gold silanolate is not the active species (as proposed during experimental studies) but is, in fact, a resting state during the transmetalation process, as a concerted step is preferred.

Structure and Reaction Chemistry of Magnesium Organocuprates Derived from Magnesiacyclopentadienes and Copper(I) Salts

“…Although the lengths of the chemical bonds of the ring, including two Mg À C(sp 2 )b onds, are comparable to those reported, the bite angle of C1-Mg-C4 (91.548 8)ismuch smaller than the classic C-Mg-C angles in the usual tetracoordinate magnesium compounds (115-1308 8). [5] This structural information, including the nearly coplanar ring skeleton and the small bite angle,i ndicates that these magnesiacyclopentadienes should possess ah igh degree of ring strain and thus should be highly reactive.Aspart of our continued interest in butadienyl-based organometallic chemistry,w ei nitiated research on the reaction chemistry of these magnesiacyclopentadienes with metal salts.W ee nvisioned that the high reactivity of these magnesiacyclopentadienes would lead them to undergo facile transmetalation reactions with CuX to generate the corresponding magnesium organocuprates,i nw hich the butadienyl skeleton should stabilize well-defined structures.H erein, we report the isolation and structural characterization of as eries of novel monomeric (Cu/Mg = 1:2) and linearly linked dimeric (Cu/ Mg = 2:3) magnesium organocuprates.These results also shed light on the transmetalation process, [6] since the product can be viewed as the resting-state intermediate of atransmetalation reaction between organomagnesium compounds and coinage-metal salts.…”

Synthesis of Gold(I)−Trifluoromethyl Complexes and their Role in Generating Spectroscopic Evidence for a Gold(I)−Difluorocarbene Species

“…Previous mechanistic studies on the reactivity of [Au(OH)(NHC)] with organosilanes (aryl−Si(OR) 3 ) point to a concerted transmetallation pathway being in play, which could afford [Au(CF 3 )(IPr)] ( 2 a ) and TMSOH as intermediates [32] . The latter two would then react with each other via an acid‐base reaction, due to the low pK a of TMSOH ( ca .…”

A Review on Oxidative Gold‐Catalyzed C‐H Arylation of Arenes – Challenges and Opportunities

“…For biaryl formation, the catalyst should be redox active and likely rotate through different oxidation states. The C–B transmetalation to gold requires Au I –X [ 31 ] (X = I, Cl, Br, F) or Au I –OH [ 32 ] as crucial intermediates. In Pd catalysis, these reactive species are easily (re)formed during catalytic turn‐over via oxidative addition of an aryl halide with Pd 0 or Pd II and subsequent counterion scrambling at Pd II or Pd IV , with an inorganic base.…”