Details

Autor(en) / Beteiligte

• Harris, Robert J.
• Nakafuku, Kohki
• Duncan, Alethea N.
• Carden, Robert G.
• Timmerman, Jacob C.
• Widenhoefer, Ross A.

Titel

Kinetics and Mechanism of the Gold‐Catalyzed Hydroamination of 1,1‐Dimethylallene with N‐Methylaniline

Ist Teil von

• Chemistry : a European journal, 2021-07, Vol.27 (40), p.10377-10386

Ort / Verlag

Germany: Wiley Subscription Services, Inc

Erscheinungsjahr

2021

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• The mechanism of the intermolecular hydroamination of 3‐methylbuta‐1,2‐diene (1) with N‐methylaniline (2) catalyzed by (IPr)AuOTf has been studied by employing a combination of kinetic analysis, deuterium labelling studies, and in situ spectral analysis of catalytically active mixtures. The results of these and additional experiments are consistent with a mechanism for hydroamination involving reversible, endergonic displacement of N‐methylaniline from [(IPr)Au(NHMePh)]+ (4) by allene to form the cationic gold π‐C1,C2‐allene complex [(IPr)Au(η2‐H2C=C=CMe2)]+ (I), which is in rapid, endergonic equilibrium with the regioisomeric π‐C2,C3‐allene complex [(IPr)Au(η2‐Me2C=C=CH2)]+ (I′). Rapid and reversible outer‐sphere addition of 2 to the terminal allene carbon atom of I′ to form gold vinyl complex (IPr)Au[C(=CH2)CMe2NMePh] (II) is superimposed on the slower addition of 2 to the terminal allene carbon atom of I to form gold vinyl complex (IPr)Au[C(=CMe2)CH2NMePh] (III). Selective protodeauration of III releases N‐methyl‐N‐(3‐methylbut‐2‐en‐1‐yl)aniline (3 a) with regeneration of 4. At high conversion, gold vinyl complex II is competitively trapped by an (IPr)Au+ fragment to form the cationic bis(gold) vinyl complex {[(IPr)Au]2[C(=CH2)CMe2NMePh]}+ (6). Kinetic and spectroscopic analyses of the gold‐catalyzed hydroamination of 1,1‐dimethylallene with N‐methylaniline support a mechanism involving rapid and reversible addition of N‐methylaniline to the more substituted terminus of gold π‐allene complex I to form gold vinyl complex II superimposed on slower addition of N‐methylaniline to the less substituted terminus of I to form gold vinyl complex III. Selective formation of the linear allylic amine 3 a is attributed to the more facile protodeauration of III relative to II.