Tris(2-pyridylthio)methyl
zinc hydride, [κ3-Tptm]ZnH,
is an effective catalyst for multiple insertions of carbonyl groups
into the Si–H bonds of Ph
x
SiH4–x
(x = 1, 2). Specifically,
[κ3-Tptm]ZnH catalyzes the insertion of a variety
of aldehydes and ketones into the Si–H bonds of PhSiH3 and Ph2SiH2 to afford PhSi[OCH(R)R′]3 and Ph2Si[OCH(R)R′]2, respectively.
The mechanism for hydrosilylation is proposed to involve insertion
of the carbonyl group into the Zn–H bond to afford an alkoxy
species, followed by metathesis with the silane to release the alkoxysilane
and regenerate the zinc hydride catalyst. Multiple insertion of prochiral
ketones results in the formation of diastereomeric mixtures of alkoxysilanes
that can be identified by NMR spectroscopy.
The first iron catalysts able to promote the formal insertion of CO into the C−N bond of amines are reported. Using low‐valent iron complexes, including K2[Fe(CO)4], amides are formed from aromatic and aliphatic amines, in the presence of an iodoalkane promoter. Inorganic Lewis acids, such as AlCl3 and Nd(OTf)3, have a positive influence on the catalytic activity of the iron salts, enabling the carbonylation at a low pressure of CO (6 to 8 bars).
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