Direct syn Insertion of Alkynes and Allenes into AuSi Bonds

Abstract

Vollständig kontrolliert: Alkine und Allene insertieren in Au‐Si‐Bindungen unter vollständiger Stereokontrolle und in den meisten Fällen unter vollständiger Regiokontrolle. Die erhaltenen β‐Silylvinylgoldkomplexe wurden spektroskopisch und kristallographisch charakterisiert. Die Ergebnisse liefern den Beweis für syn‐Insertionsreaktionen an Gold.

Direct Evidence for Intermolecular Oxidative Addition of σ(SiSi) Bonds to Gold

“…The signal for 1 a appears as a doublet (J Si, P = 39.8 Hz) and correlates with the 31 P NMR signal at d 60.9 ppm, as established by 2D HMBC( 31 P-29 Si) and 29 Si{selective 31 P} NMR experiments. [20] The magnitude of the J Si, P coupling constant that was observed for 1 a is not consistent with a phosphine gold(I) silyl structure (J Si, P (trans) = 165-210 Hz), [7,21] and may rather be attributed to the formation of a phosphine bis(silyl) gold(III) complex with a symmetric Y shape structure. However, at this stage, it was not possible to unambiguously establish the presence of two silyl groups per gold center.…”

“…[5h, 6] The feasibility of syn insertion was recently corroborated for the reaction of alkynes and allenes with silyl gold(I) complexes. [7] Reductive elimination from gold(III) complexes to form CÀC [8,9] and CÀX [10][11][12] (X = N, I, F) bonds has also been confirmed. Furthermore, reductive elimination from tetrathiolate gold(III) complexes to form S À S bonds was disclosed by Bachmann and co-workers; this reaction was found to be reversible.…”

Direct Evidence for Intermolecular Oxidative Addition of σ(SiSi) Bonds to Gold

“…The ability of gold to undergo transmetalation has been illustrated with various main group elements5 and transition metals 5h. 6 The feasibility of syn insertion was recently corroborated for the reaction of alkynes and allenes with silyl gold(I) complexes 7. Reductive elimination from gold(III) complexes to form CC8, 9 and CX10–12 (X=N, I, F) bonds has also been confirmed.…”

“…The signal for 1 a appears as a doublet ( J Si, P =39.8 Hz) and correlates with the 31 P NMR signal at δ 60.9 ppm, as established by 2D HMBC( 31 P– 29 Si) and 29 Si{selective 31 P} NMR experiments 20. The magnitude of the J Si, P coupling constant that was observed for 1 a is not consistent with a phosphine gold(I) silyl structure ( J Si, P ( trans )=165–210 Hz),7, 21 and may rather be attributed to the formation of a phosphine bis(silyl) gold(III) complex with a symmetric Y shape structure. However, at this stage, it was not possible to unambiguously establish the presence of two silyl groups per gold center.…”

Synthesis, Structure, and Reactivity of an NHC Silyl Gold(I) Complex

“…23 The Au-Si bond of 1 (2.344(1) Å) is similar to those reported for phosphine silyl gold(I) complexes (2.354(4) Å to 2.3629(16) Å). 9,10,29,30,33 The gold atom is strongly shielded by the flanking bulky Dipp groups of the NHC, likely imparting kinetic stabilization to the complex. Subsequently, the reactivity of the NHC silyl gold(I) complex 1 towards methyl propiolate was investigated (Scheme 3).…”