Development of new reagents containing silicon and related metals and application to practical organic syntheses

Our research works in the last few decades are summarized. We have studied the synthetic use of organometallics, especially organosilicon compounds, and have developed a number of new reagents and reactions useful for efficient organic synthesis. In the first section, the allylation of carbon electrophiles with allylsilanes, the so-called Hosomi-Sakurai reaction, is described. We have demonstrated that the allylation reaction is valuable not only for highly regio- and stereoselective carbon-carbon bond formation but also for introduction of a variety of functionalities. The second section deals with synthetic reactions using highly coordinated organosilanes and other organometallics, including Cr, Mn, Fe, and Cu. Higher coordination by one or more extra anionic ligands brings about unique reactivities that enable synthetically useful transformations. As shown in the third section, we developed stable 1,3-dipole equivalents protected by a silyl group and their cycloadditions, leading to N, S, or O-containing heterocycles. The following section describes the stereoselective synthesis of cyclic ethers and amines by acid-catalyzed cyclizations of vinylsilanes bearing a hydroxy or amino group. These silicon-directed cyclizations have disclosed the synthetic utility of beta-silylcarbenium ion species generated from vinylsilanes by protonation. The copper-catalyzed reactions of organosilanes via silicon-copper exchange are described in the fifth section. In the final section, our studies on homolytic carbometalation reactions are presented.