(49.79 kB)

Gold(I) Hydride Intermediate in Catalysis: Dehydrogenative Alcohol Silylation Catalyzed by Gold(I) Complex

Download (49.79 kB)
posted on 24.08.2009, 00:00 by Hajime Ito, Tomohisa Saito, Takahiro Miyahara, Chongmin Zhong, Masaya Sawamura
Gold hydride is a rare transition-metal species. Despite the fact that gold hydrides may be key intermediates in several gold-catalyzed reactions, their chemical properties are not well understood. We report the synthesis, characterization, and catalytic properties of the gold(I) hydride species that play an important role in a gold(I)-catalyzed dehydrogenative alcohol silylation. Tricoordinated complexes AuCl(xantphos) (1a) and AuCl(xy-xantphos) (1b) were prepared and characterized by 1H and 31P{1H} NMR measurements and X-ray crystallography. Gold(I) hydride species 6b generated from the reaction between 1b and PhMe2SiH (4b) in CDCl3 was characterized by 1H and 31P NMR measurements and ESI-MS spectrometry. NMR and kinetic studies revealed that the reaction mechanism involves the gold(I) hydride species as a key intermediate. The high catalytic activities of 1a and 1b in dehydrogenative alcohol silylation are explained by the stability of the tricoordinated chelating structure and the activation of the Au−Cl bond induced by the stereoelectronic effect of the coordinating phosphorus atoms. This study reports the first example of a gold(I) hydride complex that exhibits catalytic activity.