Main-Group Organometallics Containing Boron or Tin that Open New Frontiers in Organic Synthesis

Lewis acidity-diminished boron functionalities, B(dan) (dan=naphthalene-1,8-diaminato) and B(aam) (aam=anthranilamidato), have efficiently been installed into organic frameworks in a straightforward manner by a variety of catalytic borylation reactions, where chemoselective sigma-bond metathesis between a transition metal catalyst and an unsymmetrical diboron [(pin)B-B-(dan) or (pin)B- B(aam)] is a key elementary step. The dan/aam-substituted organoboranes obtained therefrom have been found to be utilized for direct cross-coupling without prior acidic deprotection, regardless of their diminished boron-Lewis acidity that usually retards transmetalation. In addition, we have also succeeded in developing copper-catalyzed aryl- and cyanostannylation of arynes, in which Lewis acidity increment of a tin center facilitates their progress.