Silylene- and Germylene-Mediated C−H Activation: Reaction with Alkanes, Ethers, and Amines

Abstract

The reaction of silylene Si[N 2 ( t Bu) 2 C 2 H 2 ] and Ph-X (X ) I, Br) in alkane and ethereal solvents results in the formation of C-H activation product [C 2 H 2 ( t Bu 2 )N 2 ]SiRI and an equivalent of benzene or oxidativeaddition product [C 2 H 2 ( t Bu 2 )N 2 ]SiPhI. The ratio of products obtained is dependent upon substrate and concentration. This class of reaction has been extended for Si[N 2 ( t Bu) 2 C 2 H 2 ] and Ge[CH(SiMe 3 ) 2 ] 2 to alkylamines. The primary kinetic isotope effect has been measured for the reaction of Si[N 2 ( t Bu) 2 C 2 H 2 ] with Et 2 O and determined to be k H /k D ) 5.1 ( 0.1. The reaction of Ge[CH(SiMe 3 ) 2 ] 2 and Ph-Br with THF was determined to be second order. A large isotope effect ranging from 1.8 to 1.1 was measured for a variety of deuterated aryl halides, consistent with an initial electron transfer to the aryl halide.

N‐Heterocyclic Silylene Main Group Element Chemistry: Adduct Formation, Insertion into E−X Bonds and Cyclization of Organoazides

“…These investigations reveal that t Bu 2 NHSi and t Bu 2 NHSi H2 react with a variety of chloro‐ or bromocarbons to yield to the monosilanes H , disilanes I or mixtures of both, depending on the halocarbon and the stoichiometric ratio used (Figure 9, top left) [4c,24a] . Holl and co‐workers reacted t Bu 2 NHSi with phenyl iodide to obtain t Bu 2 NHSi(I)(Ph), and subsequent addition of N ‐methyl piperidine led to the isolation of t Bu 2 NHSi(I)(Py Me ) via a C−H activation in ortho ‐position of the piperidine nitrogen atom [24b] . Furthermore, it was shown that two molecules of the benzannulated, CH 2 t Bu substituted silylene ( t BuCH 2 ) 2 NHSi benz insert into the C−Cl (C−Br) bonds of dichloromethane or dibromo methane, respectively, to give the methylene bridged disilane J (Figure 9, bottom left) [29] .…”

Triethylamine Hydroiodide as a Simple Yet Effective Bifunctional Catalyst for CO2 Fixation Reactions with Epoxides under Mild Conditions

“…That is to say, H 2 O was included in the reaction mixture. It is known that H 2 O is an effective additive to promote the CO 2 fixation reactions with tetraalkylammonium iodide catalysts. , To clarify the effect of H 2 O in the present reaction system using a triethylamine hydroiodide catalyst, we prepared a dry triethylamine hydroiodide catalyst, and the catalytic ability was compared with an in situ -generated catalyst including water (Scheme ). The pre-prepared dry triethylamine hydroiodide catalyst exhibited basically the same catalytic activity with the in situ -generated catalyst including water, and product 2a was obtained in high yield (94% yield).…”

Calix[4]pyrrole Hydridosilicate: The Elusive Planar Tetracoordinate Silicon Imparts Striking Stability to Its Anionic Silicon Hydride

“…IR spectroscopy for salts [ 1 -H – ]­[M + ] showed distinct stretching modes of the Si–H bonds at 2176 cm –1 [K+] or 2243 cm –1 [PPh 4 + ]. Such values are much higher compared to other hydridosilicates (1550–1970 cm –1 ), ,, but rather match with those of Si–H bonds in neutral silanes or aminosilanes (2100–2200 cm –1 ). ,, The IR-spectra thus indicate a remarkably strong Si–H bond in [ 1 -H – ].…”