Precursor of boronic esters by hydroboration or coupling reactions. Hydroboration of alkynes, in the presence of Rh or Ni catalysts, yields alkenylboronates: Tetrahedron Lett., 37, 3283 (1996). Hydroboration of alkenes in the presence of Chlorotris(triphenyl-phosphine)-rhodium(I)-, affords the alkylboronate: Tetrahedron Lett., 37, 3283 (1996); with phosphine-free catalyst Chloro(1,5-cyclooctadiene)-rhodium(I)- dimer, dehydrogenative borylation predominates to give the alkenylboronate: Tetrahedron Lett., 40, 213 (1999); Bull. Chem. Soc. Jpn., 75, 825 (2002).Coupling aryl iodides and bromides, catalyzed by [1,1'-Bis(diphenyl-phosphino)-ferrocene]palladium(II)- chloride, gives the aryl pinacolboronates: J. Org. Chem., 62, 6458 (1997); 65, 164 (2000). In the presence of triphenylarsine, Pd-catalyzed coupling with alkenyl triflates and iodides affords vinylboronates: Synthesis, 778 (2000). For a brief review of uses of pinacolborane, see: Synlett, 1210 (2000).
