Abstract
Significant developments have been achieved in recent years toward the utilization
of (RO)2 B–B(OR)2 for exploring transition-metal-free organic transformations in organic synthesis.
Among the various combinations of Lewis bases with diborons developed so far, pyridine
derivatives are simple, commercially available, and cheap compounds to expand the
synthetic utility of diborons by generating borylpyridine anions and pyridine-stabilized
boryl radicals via B–B bond cleavage. These borylpyridine species mediate a series
of transformations in both a catalytic and stoichiometric manner for C–X activation
(X = halogen, CO2 H, NR2 ) and concomitant C-borylation, hydroborylation, C–C bond formation, and reduction
reactions.
1 Introduction
2 Reaction Pathway for B–B Bond Cleavage of Diborons with Electron-Deficient Pyridines
3 Pyridine-Mediated B–B Bond Activation of (RO)2 B–B(OR)2 for Application in Organic Synthesis
3.1 Dehalogenative C-Borylation
3.2 Desulfonative C-Borylation
3.3 Decarboxylative C-Borylation
3.4 Deaminative C-Borylation
3.5 Hydroborylation
3.6 C–C Bond Formation
3.7 Pyridine Functionalization
3.8 Deoxygenation and N-Borylation Reactions
4 Conclusions
Key words diboron - pyridine - B–B bond cleavage - borylation - single-electron transfer - radical
reaction
