Suzuki-Miyaura reaction rhodium catalysts

Supported rhodium(O) catalysts have also been reported to catalyse a range of cross-coupling reactions. For example, a layered double hydroxide (LDH) supported catalyst has been successfully used in the traditional Suzuki-Miyaura reaction to afford biaryl compounds in excellent yield. The catalyst could be quantitatively recovered from the reaction mixture by simple filtration and reused for several runs with consistent activity in all the reactions. The catalyst was also simply prepared by treating LDH-CO3 (Mg Al = 3 1) with RhCl3-H20 in doubly deionized water. 

Rhodium has been successfully used in a range of Suzuki-Miyaura type reactions. Satoh and Miura have reported the Suzuki-Miyaura-type cross-coupling of arylboron compounds with aryl halides in the presence of a rhodium-based catalyst system to produce the corresponding biaryls (Scheme 13.21). They also found, unexpectedly, that when employing benzonitrile as substrate under similar reaction conditions a multiple arylation is observed, in which nucleophilic arylation on the cyano group and subsequent ortho arylation via C-H bond cleavage is involved. 

In contrast to olefins, little is known on catalytic hydroboration of conjugated dienes. Suzuki and Miyaura described a 1,4-addition of catecholborane to acyclic 1,3-dienes, catalyzed with tetrakis(triphenylphosphine)palladium(0). An interesting Markovnikov type regioselectivity was observed in the enantioselective dihydroboration of (E)-1-phenyl-1,3-butadiene with catecholborane, catalyzed by chiral rhodium complexes. However, the scope of these reactions is not well known, and the choice of catalysts is very limited. 

---