extremely facile and rapid C-Si bondcleavage in supercritical water. The rapid C-Si bondcleavage occurred even with robust unactivated tetraalkylsilanes. The control experiments revealed the dramatic difference between supercritical and subcritical conditions and that between supercritical water and supercritical methanol, attesting to a unique reactivity of supercritical water in C-Si bondcleavage.
A Pd-catalyzed oxidative silylation of simple olefins with hexamethyldisilane to give allylsilanes has been achieved usingmolecularoxygen as the sole oxidant. The reaction provides a useful protocol to access synthetically useful allylsilanes from easily accessible simple olefins and hexamethyldisilane without using any oxidants other than O2.
Metalation of alk-1-enes, using the mixture of butyllithium and potassium tert-butoxide in tetrahydropyran, followed by stereohomogenization and ultimate treatment with chlorotrimethylsilane afforded a series of alk-2-enyltrimethylsilanes in good yield and with (Z/E) ratios ranging from 95:5 to 98:2. The deprotonation of propene can be rapidly and readily accomplished with a stoichiometric amount of the superbase suspended in pentane on a 1 mol scale.
[2-(Trimethylsilyl)ethylidene]tris(2-methylphenyl)phosphorane, a modified seyferth-wittig reagent for the stereoselective syntheses of -allyltrimethylsilanes
In the presence of catalytic amounts of platinum(II) chloride and silver(I) hexafluoroantimonate, (Z)-alkenylsilanes reacted with various carbon electrophiles (acetals, aminals, carboxylic anhydrides, alkyl chlorides, etc.) at the -position to give allylation products. A plausible mechanism for the platinum-catalyzed allylation involves alkene migration of alkenylsilanes to allylsilanes and subsequent allylation of carbon electrophiles, both of which are catalyzed by a cationic platinum(II) species.