Migration trimethylsilyl groups

The most reasonable explanation for this is that the photochemical [l,2]silyl shift in 14e yields carbene 13e in its s-E conformation. This carbene either rearranges back to I4e or produces the conformational isomer s-Z-13e (Scheme 7). Since the migrating trimethylsilyl group is located syn to the methyl group, the silyl shift in i-Z-13e is expected to be less feasible than in the s-E conformer, and thus the [1,2]H shift to s-Z-16 can compete. Since the vinyloxysilanes 16 and 8 are both formed in the s-Z conformation it is tempting to assume that a similar mechanism is operating. 

Upon irradiation of (dimesityl)(trimethylsilyl)silylazide at 254 nm in a cyclohexane/t-butanol or a cyclohexane/ethanol solution, migration of the trimethylsilyl group to the nitrene center is observed (Eq. 2). The products are equivalent to the addition products mentioned above. 

A similar reaction of a silicon-amino substituted silene [11] supports this mechanism. The migration of a trimethylsilyl group from the Si-amino substituent to the nucleophilic carbon atom of the Si=C moiety leads to the diazasilacyclopentane 30. 

The migration of the trimethylsilyl group would help to open the four-membered ring of (503), and as a result, the dichlorotrimethylsilylenol ether (504) was... 

Addition of trimethylsilyl azide to acetylenes gives the 2.ff-isomers directly, and the 1. -isomers are not detected. A very ready migration of the trimethylsilyl group must take place in those triazoles. Similar rearrangements occur in additions of trialkyltin azides. ... 

When we identify trimethylsiloxy-l,2-dioxetane and assign trimethylsi-loxymethyl formate as a reaction product, we demonstrate how feasible the trimethylsilyl group migration is. (Adapted from Fajgar et ah, 2001)... 

The identification of trimethylsiloxy-l,2-dioxetane and the assignment of trimethylsiloxymethyl formate as a reaction product demonstrate the feasibility of a trimethylsilyl group migration. 

Fajgar, R. Roithova, J. Pola, J. Trimethylsilyl Group Migrations in Cryogenic Ozonolysis of Trimethylsilylethene Evidence for Nonconcerted Primary Ozonide Decomposition Pathway. . Org. Chem. 2001, 66, 6977-6981. 

Methoxy[(trimethylsilyl)ethoxy]carbene - obtained by thermolysis of the corresponding oxadiazoline 337 - reacts with Cgo in an unprecedented reaction pathway [383,384]. The expected methanofullerene-[2-i-l]-cycloadduct could not be observed. Instead the two dihydrofullerene adducts 338 and 339 were isolated (Scheme 4.69). They are formed by an unusual addition-rearrangement mechanism that includes the migration of the trimethylsilyl group. 

Cleavage of epoxidesThe aiiion (2) of 1 reacts with carbonyl compounds to give a,/(-unsaturated nitriles and LiOSi(CH3)3, as expected.2 The reaction with epoxides is unexpected the products are y-trimethylsilyloxynitriles, which are useful precursors to -/-lactones (equation I). The formulation indicates that a 1,4-migration of the trimethylsilyl group is involved.2... 

The formation of methanolysis product 25 (R = Me) was easily understood in terms of ketene acetal structure 24. However, the isolated thermal product 26 is not directly derived from the ketene acetal 24. It is not unreasonable to suggest that thermal transformation of the [2 + 4] adduct 24 into the [2 + 2] adduct 23 takes place, followed by intramolecular migration of the trimethylsilyl group to afford vinylsiloxane... 

Reaction of allylpyrrolidine with n-butyllithium in TMEDA leads, after silylation, to a silylated enamine further treatment with n-butyllithium results in the 1,3-migration of the trimethylsilyl group to the corresponding SMA derivative in poor yield after silylation. In the presence of magnesium bromide, 1-trimethylsilylallylpyrrolidine is formed selectively in moderate yield.125... 

Aluminium halides are not only able to split methyl groups, but to undergo other reactions, too. The chloromethyldisilane derivatives can be further reacted by rearrangement365. The products depend on the reaction conditions. Kumada et al.356 found that, under mild conditions (reaction temperature 70-80 °C), only migration of the trimethylsilyl group from silicon to carbon takes place ... 

Zurmtihlen and Regitz prepared silyloxyiminophosphine by the condensation-silatropy method in the reaction of the silylphosphide lib with nitrosyl chloride (equation 96)70. The condensation-silatropy method has also been utilized for the introduction of pln=pln bonds. Romanenko and coworkers prepared diphosphene via phosphaethene (equation 97), in a reaction where one of the trimethylsilyl groups migrated onto the carbon atom121. 

When 2-substituted (methyl or trimethylsilyloxy) 2-norbornenes and 1,7,7-trimethyl-2-norbor-nenes are allowed to react with singlet oxygen, ene products are efficiently formed53 54. In the case of the trimethylsilyloxy-substituted substrates, migration of the trimethylsilyl group occurs and O-silylated a-hydroperoxy ketones 1 are isolated. The O-silylated a-hydroperoxy ketones 1 arc easily reduced to O-silylated a-hydroxy ketones. 

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