- Hydrosilane σ-Adduct Intermediates in an Adaptive Zinc-Catalyzed Cross-dehydrocoupling of Si?H and O?H Bonds
-
Three-coordinate PhBOX (Formula presented.) ZnR (PhBOX (Formula presented.) =phenyl-(4,4-dimethyl-oxazolinato; R=Me: 2 a, Et: 2 b) catalyzes the dehydrocoupling of primary or secondary silanes and alcohols to give silyl ethers and hydrogen, with high turnover numbers (TON; up to 107) under solvent-free conditions. Primary and secondary silanes react with small, medium, and large alcohols to give various degrees of substitution, from mono- to tri-alkoxylation, whereas tri-substituted silanes do not react with MeOH under these conditions. The effect of coordinative unsaturation on the behavior of the Zn catalyst is revealed through a dramatic variation of both rate law and experimental rate constants, which depend on the concentrations of both the alcohol and hydrosilane reactants. That is, the catalyst adapts its mechanism to access the most facile and efficient conversion. In particular, either alcohol or hydrosilane binds to the open coordination site on the PhBOX (Formula presented.) ZnOR catalyst to form a PhBOX (Formula presented.) ZnOR(HOR) complex under one set of conditions or an unprecedented σ-adduct PhBOX (Formula presented.) ZnOR(H?SiR′3) under other conditions. Saturation kinetics provide evidence for the latter species, in support of the hypothesis that σ-bond metathesis reactions involving four-centered electrocyclic 2σ–2σ transition states are preceded by σ-adducts.
- Patnaik, Smita,Kanbur, Uddhav,Ellern, Arkady,Sadow, Aaron D.
-
supporting information
p. 10428 - 10436
(2021/05/27)
-
- Catalytic Reduction of Alkoxysilanes with Borane Using a Metallocene-Type Yttrium Complex
-
The catalytic reduction of alkoxysilanes with the borane HBpin (pin = pinacolato) was achieved using a metallocene-type yttrium complex as a catalyst precursor. Mechanistic study supported the pivotal role of the rigid metallocene structure of the catalyst, which bears two bulky n5-C5Me4SiMe3 ligands, in suppressing the coordination of the side product MeOBpin that is generated during the reaction.
- Aoyagi, Keiya,Matsumoto, Kazuhiro,Shimada, Shigeru,Sato, Kazuhiko,Nakajima, Yumiko
-
supporting information
p. 210 - 212
(2019/02/01)
-
- Synthesis and structures of o-(dihydrosilyl)(dimesitylboryl)benzenes
-
O-(Dihydrosilyl)(dimesitylboryl)benzenes 1 were prepared in 6 steps. o-Dibromobenzene was mono-lithiated with n-BuLi and reacted with chloro(dimethoxy)silanes to afford o-C6H4(Br)[SiR(OMe) 2] (2) (R = Ph, Me). Bromine-lith
- Kawachi, Atsushi,Morisaki, Hiroshi,Zaima, Masatoshi,Teranishi, Takuya,Yamamoto, Yohsuke
-
experimental part
p. 2167 - 2171
(2010/09/15)
-
- Convenient synthesis of alkoxyhalosilanes from hydrosilanes
-
Selective dehydrogenative coupling of di- and trihydrosilanes with alcohols catalyzed by PdCl2 or NiCl2 afforded alkoxyhydro- and dialkoxyhydrosilanes in good yield. Further treatment of the resulting alkoxyhydrosilanes with carbon tetrachloride or allyl bromide in the presence of the same catalyst led to the formation of alkoxychloro- and alkoxybromosilanes, respectively. Similar reactions of dialkoxyhydrosilanes with carbon tetrachloride afforded dialkoxychlorosilanes in good yield, although contamination of small amounts of trialkoxysilanes and alkoxydichlorosilanes was detected in the products. Selective substitution of the alkoxyhalosilanes with nucleophiles is also reported.
- Ohshita, Joji,Taketsugu, Ryosuke,Nakahara, Yuki,Kunai, Atsutaka
-
p. 3258 - 3264
(2007/10/03)
-