When alpha to a sulfoxide group, groups containing this element migrate in a common variation of the Pummerer rearrangement. Transmetalation of groups from this element to palladium is a key step in the Hiyama cross-coupling. When groups containing this element are geminal or vicinal to hydroxyl groups, they rearrange to ethers of this element in the Brook rearrangement. Enol derivatives of those ethers of this element are reacted with aldehydes or formates in the Mukaiyama aldol reaction, and ethers of this element are generally useful protecting groups for alcohols. The tetramethyl derivative of this element is defined to have a chemical shift of 0 ppm in proton NMR, and its dioxide is the
When alpha to a sulfoxide group, groups containing this element migrate in a common variation of the Pummerer rearrangement. Transmetalation of groups from this element to palladium is a key step in the Hiyama cross-coupling. When groups containing this element are geminal or vicinal to hydroxyl groups, they rearrange to ethers of this element in the Brook rearrangement. Enol derivatives of those ethers of this element are reacted with aldehydes or formates in the Mukaiyama aldol reaction, and ethers of this element are generally useful protecting groups for alcohols. The tetramethyl derivative of this element is defined to have a chemical shift of 0 ppm in proton NMR, and its dioxide is the main component of glass. For 10 points, name this tetravalent element used in microchips.