Organoboron reagents, arylation with

As far as we are aware, there have been no other reports on the arylation of imine substrates with ruthenium catalysts, besides our own work. In 2012, we published our efforts at developing a Ru-catalyzed asymmetric catalytic imine arylation with organoboron reagents and with chiral phosphane and new NHC-type ligands (Scheme 6.33) [44]. 

Reactions of organoboron polymer electrolytes with aryllithium reagents suffered low conversion due to relatively low reactivity of the mesitylborane unit. Moreover, incorporation of aryl substituent in side chains resulted in higher glass-polymer electrolyte-transition temperatures. 

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). 

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... 

Aryl mesylates are used for the Ni-catalysed cross-coupling with Grignard, organozinc and organoboron reagents [100]. 

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. 

The mechanism of this transformation was not investigated, however a possible mechanism was proposed (Scheme 32). Transmetalation of the organoboron reagent to a rhodium(I) center could be followed by coordination of the imine, oxidative addition of the ortho C-H bond and reductive elimination to afford the ortho arylated product and a rhodium(I) hydride. Reoxidation would then follow through insertion of the imine in to the Rh-H bond followed by protonation with NH4C1. 

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