Cross-coupling main group organometallic

Cross-Coupling Reactions with Organometallic Compounds of the Main Group Metals via Transmetallation... 

Cross-Coupling with Main Group Organometallic Compounds... 

Allylic compounds undergo smooth Pd-catalyzed cross-coupling with main group organometallic compounds as expected. Substitution occurs mainly at less-substituted allylic termini. A few examples are cited here. 

Also covered is the stabilisation of Ge, Sn, and Pb carbanion equivalents, carbene analogues, cyclotrisilanes and tristannanes. Main Group organometallics in synthesis, applications of Si and Sn in borane chemistry and cross-coupling, disilenes and... 

The progress on S-C bond activation, which covers the reduction of a C-S bond to a C-H bond, cross coupling reaction of sulfides with main group organometallic nucleophiles, ring opening reactions of thietanes and thiiranes, and desulfurization of thiols, sulfides, and thiophenes has already been reviewed elsewhere [6-10], and... 

C-C, C-H, C-N, C-0, C-S, C-P or C-M bond formation. Among them, transmeta-lation is the most characteristic of the cross-coupling reaction because this process combines the attributes of transition metals and main group metal reagents. However, the transmetalation is less understood than the other two steps since it is highly dependent on the nature of the organometallic reagents and the reaction conditions, as is discussed in several chapters of this book. 

Oxidative addition of aryl (or vinyl) halide to Pd(0) precursor forms the monoarylpalladium complex that is the common intermediate in the catalytic cross-coupling reactions of haloarene with organometallic compounds of main group elements such as Mg, Si, and Sn. Alkynylcopper, formed from alkyne, Cu(I) salt and base in the reaction mixture, transfers the ligand to the above Pd complex, giving an intermediate complex with aryl (or vinyl) and alkynyl ligands bonded to Pd. Reductive elimination of arylacetylene (or enyne) occurs... 

Cross-coupling proceeds by transmetallalion of 1 with organometallic compounds of main group metals (Mg, Zn, B, Al, Sn, Si) and reductive elimination to give 12 as summarized in Scheme 3.3. 

---