ORGN 311 |
| While silylmetalation is a versatile method to prepare organosilicon compounds, reactions of inactivated olefins as substrates have been unsuccessful. Recently we have revealed that the dianion-type silylzincate complexes promote highly chemoselective silylzincation of terminal alkynes in the absence of any transition metal catalysts. In our study of scope and limitation of this silylzincation, we found that two kinds of products can be obtained from terminal alkenes, and varying the transition metal catalysts can control the selectivity of the product. Namely, in the presence of copper cyanide, the silylation occurs at the terminal carbon atom selectively and the resultant alkyl zinc intermediates can be trapped by various electrophiles such as deuterium oxide, ally halide, and propargyl halide to give alkylsilanes. On the other hand, in the case of titanocene dichloride, the silylation also occurs regiospecifically at the terminal carbon atom, and subsequent regioselective hydride elimination can occur spontaneously, which gives allylsilanes. |
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Metal-Mediated Reactions and Syntheses
1:00 PM-5:00 PM, Monday, 11 September 2006 Moscone Center -- Room 133, Oral
Division of Organic Chemistry |