Organoboron reagents reaction

The first example of asymmetric rhodium-catalyzed 1,4-addition of organoboron reagents to enones was described in 1998 by Hayashi and Miyaura. Significant progress has been made in the past few years. This asymmetric addition reaction can be carried out in aqueous solvent for a broad range of substrates, such as a,/ -unsaturated ketones, esters, amides, phosphonates, nitroalkenes. The enantioselectivity is always very high (in most cases over 90% ee). This asymmetric transformation provides the best method for the enantioselective introduction of aryl and alkenyl groups to the / -position of these electron-deficient olefins. 

Since the C—B bond is almost completely covalent, transmetalation of an organoboron reagent to transfer the organic group will not occur without coordination of a negatively charged base or a F to the boron atom. As a consequence, the Suzuki reaction normally needs to be carried out in a basic solution, which poses some limitations to base-sensitive substrates. 

In addition, Wipf and co-workers104 have used silver(i)-catalyzed addition of zirconocenes to 3,4,6-tri-O-benzyl-D-glucal epoxide 93 for the stereoselective synthesis of a-C-glucosyl compounds 95 and 96 following a similar mechanism as in the reaction with organoaluminium and organoboron reagents (Scheme 32). 

Zapf, A. Coupling of Aryl and Alkyl Halides With Organoboron Reagents (Suzuki Reaction). In Transition Metals for Organic Synthesis (2nd edn), Beller, M. Bolm, C. eds., 2004, 1, 211-229. Wiley-VCH Weinheim, Germany. (Review). 

Reactions with Organoboron Reagents The Suzuki-Miyaura Reaction... 

Reaction with Organoboron Reagents (Suzuki-Miyaura Coupling) 660... 

Palladium-monophosphine complexes catalyse trans-selective arylative, alkenyla-tive, and alkylative cyclization reactions of alkynals [e.g. (68)] and alkynones with organoboronic reagents. These reactions afford six-membered allylic alcohols (69) (g) and/or their five-membered counterparts (70), whose ratios are dramatically affected... 

One limitation to the scope of the Suzuki reaction has been its inefficiency when aryl chlorides are employed as substrates. Recently, Buchwald and Fu have discovered the palladium-catalyzed cross-coupling of aryl chlorides with organoboron reagents, employing highly active palladium catalysts mediated by special ligands. These are discussed in Section 3.4. 

Suzuki reaction Reaction of an organic halide with an organoboron reagent in the presence of a palladium catalyst (Section 26.2)... 

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