Cross Hiyama coupling

The C-C bond forming reaction of an organic halide with an organosilane, catalysed by nickel or palladium, is known as the Hiyama cross-coupling. Typically the C-Si bond needs to be activated by either electronegative substituents or by external fluoride anions. 

Yoshida and co-workers have reported on the use of alkenyldimethyl(2-pyridil)silanes as versatile platforms for olefin synthesis.The combination of Mizoroki-Heck-type coupling and Hiyama cross-coupling provided a diverse range of stereodefmed polysubstituted olefins. 

The Hiyama cross-coupling of organosilanes is attractive as the intermediates are often easy to prepare and the silicon by-products are environmentally benign. A one-pot synthesis of 2-aryl-3-methylpyridines from 2-bromo-3-methylpyridine was developed (Scheme 25) <2003JOM58>. Both 2- and 3-bromopyridine cross-couple with phenyltrimethoxysilane to afford the corresponding phenylpyridines in good yield <19990L2137>. 

Gros and co-workers have shown that the presence of electron-withdrawing substituents on the pyridine ring of 2-trimethylsilylpyridines provides sufficient activation to allow them to be useful partners in the Hiyama cross-coupling. 

Tsuji-Trost allylation reactions offer multiple pathways to tetrahydrofuran synthesis including C-C bond-formation steps. A palladium-catalyzed sequence of allylic alkylation and Hiyama cross-coupling provides a convenient synthesis of 4-(styryl)-lactones (Scheme 67) <2006SL2231>. 

Table 7 Hiyama cross-coupling of primary alkyl bromides and iodides with aryltrimethoxy-silanes...

Table 7 provides examples that illustrate the scope of this room-temperature Hiyama cross-coupling of unactivated primary alkyl bromides and iodides. The method is compatible with functional groups such as esters, cyanides, and ketones. 

Yet L. Hiyama Cross-Coupling Reaction. In Name Reactions for Homologations-Part I Li, J. J., Corey, E. J., Eds. Wiley Sons Hoboken, NJ, 2009, pp 33-416. (Review). 

In polar solvents or at higher temperatures, the fluorine-silicon bridge would be cleaved to switch the transition-state model to the Sg2(open) (72), thus resulting in inversion. On the other hand, open and cyclic Sg2 mechanisms have been proposed to justify the observed stereochemistry in the y-selective cross-coupling of allylsilanes [298]. Allylic silanolates undergo the palladium-catalyzed Hiyama cross-coupling with aromatic bromides with excellent stereoselectivity through a syn SE transmetallation [299]. 

Welker developed a useful synthetic strategy involving silyl substituted dienes. He can easily prepare large quantities of 2-silicon-substituted 1,3-dienes that readily participate in Diels-Alder reactions followed by cross-coupling reactions to yield aryl substituted cyclohexenes. Diene 94 smoothly combines with A-phenylmaleimide (95) to fiimish a silyl cyclohexene that undergoes Hiyama cross-coupling with iodobenzene to provide 96. ... 

---