Insertion reactions of carbenes or ylides with organoboronic acids or their derivatives
have emerged as valuable methods for coupling or homologation of organoboron compounds
under metal-free conditions. The crucial steps of these reactions are coordination
of the electron-rich carbon centers of the carbene precursors or ylides to the electron-poor
boron center, followed by 1,2-migration of the corresponding tetracoordinated boron
intermediates. This type of unique transformation provides an efficient method for
the construction of C–C or C–X (X = H, B) bonds. Moreover, the C–B bonds generated
by such transformations can be utilized as a handle for further derivatization or
iterative homologations. In this Account, we summarize the developments in this arena
according to the reactive diazo compound, N-arylsulfonylhydrazone or ylide species involved.
Key words
diazo compounds - ylides -
N-tosylhydrazones - organoboronic acids - 1,2-migration