- Tris(trimethylsilylmethyl)alane: An aldehyde selective peterson methylenation reagent
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Tris(trimethylsilylmethyl)alane (TTMA) is a rapid, efficient, and highly aldehyde-selective trimethylsilylmethylating reagent. A solid lithium halide complex of the reagent, TTMA·3LiBr (TTMAs), is particularly effective in this transformation to the Peterson alcohol intermediate.
- Abedi, Vahak,Battiste, Merle A.
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p. 1856 - 1859
(2007/10/03)
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- Silicon Effects. V. β-Silicon Effect in the Solvolysis of 2-Phenylethyl Compounds
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The rates of the solvolysis of 2-aryl-2-(trimethylsilyl)ethyl compounds, ArCH(SiMe3)CH2X (4: X=Cl and OCOCF3; Ar=C6H5 and p-MeOC6H4), have been measured in various solvents at 25 deg C.The solvolysis of the chloride, 4 (X=Cl; Ar=C6H5), exhibited an m valu
- Hayakawa, Fumie,Watanabe, Sin-ichiro,Shimizu, Nobujiro,Tsuno, Yuho
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p. 153 - 157
(2007/10/02)
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- Mechanism of Thermal Eliminations. Part 30. Pyrolysis of 2-Trimethylsilylethanol and 1-Aryl Derivatives
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The Arrhenius parameters (Eact = 45.57 kcal mol-1, log A/s-1 = 12.865) and rate coefficient at 600 K (1.84 * 10-4 s-1) for the cis β-thermal elimination of trimethylsilanol from 2-trimethylsilylethanol are identical (within experimental error) with those reported in the literature for elimination of methyl trimethylsilyl ether from 1-methoxy-2-(trimethylsilyl)ethane.This indicates that the driving force for the reaction, formation of the Si-O bond, is such that alteration of the nucleophilicity of oxygen has little effect on the reaction rate.A series of 1-aryl-2-trimethylsilylethanols have been prepared and their rates of elimination determined.The activating effect of the 1-aryl substituent (5.2-fold) is much less than the corresponding effect in the pyrolysis of ethyl acetates (63-fold) and 2-trimethylsilylethyl acetates (87-fold).Breaking of the α-C-O bond is thus kinetically less important than in the other reactions, and this conclusion is confirmed by a correlation of the rate data with the Yukawa-Tsuno equation which gives ρ = -0.4, r = 0.3.Si-O bond formation in the reaction is thereby shown to be of over-riding kinetic importance.For the 4-methylphenyl- and 4-methoxyphenyl compounds a minor competing reaction was the elimination of water to give the corresponding 1-aryl-2-trimethylsilylethene, and this has a higher activation energy than for the elimination of trimethylsilanol.NMR spectra for the 1-aryl-2-trimethylsilylethanols show that interaction between the OH and SiMe3 groups inhibits free rotation about the C(1)-C(2) bond.Preparation of 1-aryl-2-trimethylsilylethanols gave 1,3-diaryl-4-trimethylsilylbutyl trimethylsilyl ethers as byproducts arising from elimination of water from two molecules of the alcohols in a process believed to be two-step.
- Taylor, Roger
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p. 1703 - 1706
(2007/10/02)
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