Organoboron compounds metal-catalyzed

Other than transition metals, organoboron compounds also catalyzed hydroalumination (Scheme 6.140). Regio- and chemoselectivity was extremely good [180]. 

Direct borylation of hydrocarbons catalyzed by a transition metal complex has been extensively studied by several groups and has become an economical, efficient, elegant, and environmentally benign protocol for the synthesis of a variety of organoboron compounds. The Rh-, Ir-, Re-, and Pd-catalyzed C-/H borylation of alkanes, arenes, and benzylic positions... 

Fig. 16.18. Representative mechanism of the Pd-catalyzed C,C coupling of an organoboron compound. The elementary steps, discussed in the text, are (1) complexation, (2) oxidative addition, (3) transmetalation of the alkenylboron compound to afford an alkenylpalladium compound, (4) reductive elimination, and (5) dissociation of the coupled product from the metal. - Note Regarding the arrangement of the ligands around the metal center of the individual intermediates and the details of the transmetalation the present mechanistic analysis is less complete than the mechanistic analysis of other Pd-catalyzed C,C couplings, namely the Stille coupling (Figure 16.27) or Heck reaction (Figure 16.35, part II), which have been investigated in great detail.

S. Suzuki, Cross-Coupling Reactions of Organoboron Compounds with Organic Halides, in Metal-catalyzed Cross-coupling Reactions (F. Diederich, P. J. Stang, Eds.), Wiley-VCH, Weinheim, 1998, 49-89. 

Fig. 13.14. Representative mechanism of the Pd-catalyzed C,C coupling of an organoboron compound. The elementary steps, discussed in the text, are (1) complexation, (2) oxidative addition, (3) transmetallation of the alkenylboron compound to afford an alkenylpalladium compound, (4) reductive elimination, and (5) dissociation of the coupled product from the metal.

The metal-catalyzed addition reaction of organoboron compounds have not yet been well developed, but die reaction of NaBPh4 or arylboronic acids with enones in the presence of Pd(OAc)2 and NaOAc or SbCL, was recently reported by Uemura and his coworkers.2 The reaction was proposed to proceed through the oxidative addition of the C-B bond to the Pd(0) species however, another probable process, the transmetalation to transition metals, may allow a similar catalytic transformation by the use of organoboronic acids. We report here the 1,4-addition reaction of organoboronic acids to oc, J-unsaturated ketones or esters and 1,2-addition to aldehydes or imines catalyzed by a (acac)Rh(CHj=CH2)2/phosphine complex, which may involve the B-Rh transmetalation as the key step. 

Suzuki, A. Cross-coupling reactions of organoboron compounds with organic halides. Metal-Catalyzed Cross-Coupling Reactions 1998,49-97. 

Ishiyama, T., Miyaura, N. Metal-catalyzed reactions of diborons for synthesis of organoboron compounds. Chemical Record 2004, 3, 271-... 

Miyaura N (2004) Metal-catalyzed cross-coupling reactions of organoboron compounds with organic halides. In De Meijere A, Diederich F (eds) Metal-catalyzed cross-coupling reactions. Wiley-VCH, Weinheim, p 41... 

State-of-the-Art in Metal-Catalyzed Cross-Coupling Reactions of Organoboron Compounds with Organic Electrophiles... 

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