Analysis of an unprecedented mechanism for the catalytic hydrosilylation of carbonyl compounds.
This work details an in-depth evaluation of an unprecedented mechanism for the hydrosilylation of carbonyl compounds catalyzed by (PPh3)2Re(O)2I. The proposed mechanism involves addition of a silane Si-H bond across one of the rhenium-oxo bonds to form siloxyrhenium hydride intermediate 2 that reacts with a carbonyl substrate to generate siloxyrhenium alkoxide 4, which, in turn, affords the silyl ether product. Compelling evidence for the operation of this pathway includes the following: (a) isolation and structural characterization by X-ray diffraction of siloxyrhenium hydride intermediate 2, (b) demonstration of the catalytic competence of intermediate 2 in the hydrosilylation reaction, (c) 1H and 31P{1H} NMR and ESI-MS evidence for single-turnover conversion of 2 into 1, (d) observation of intermediate 2 in the working catalyst system, and (e) kinetic analysis of the catalytic hydrosilylation of carbonyl compounds by 1.
Nolin
Kristine A
KA
Department of Chemistry, University of California, Berkeley, California 94720, USA.
Krumper
Jennifer R
JR
Pluth
Michael D
MD
Bergman
Robert G
RG
Toste
F Dean
FD
D000447:Aldehydes / Q000737:chemistry; D002255:Carbonic Acid / Q000737:chemistry*; D002384:Catalysis; D006859:Hydrogen / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D012211:Rhenium / Q000737:chemistry; D012821:Silanes / Q000737:chemistry*; D013237:Stereoisomerism
D000447:Aldehydes; D007659:Ketones; D012821:Silanes; D002255:Carbonic Acid; D012211:Rhenium; D006859:Hydrogen