Synthesis 2021; 53(18): 3211-3226
DOI: 10.1055/a-1486-8169
special topic
Bond Activation – in Honor of Prof. Shinji Murai

Pyridine-Mediated B–B Bond Activation of (RO)2B–B(OR)2 for Generating Borylpyridine Anions and Pyridine-Stabilized Boryl Radicals as Useful Boryl Reagents in Organic Synthesis

Luis C. Misal Castro
,
,
,
Kazushi Mashima
L.C.M.C. acknowledges the financial support by the Japan Society for the Promotion of Science (JSPS) Research Fellowships (P18336). I.S. acknowledges the scholarship from Japan International Cooperation Agency (JICA) Innovative Asia Program (D1805473).


Abstract

Significant developments have been achieved in recent years toward the utilization of (RO)2B–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, CO2H, 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)2B–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



Publication History

Received: 03 March 2021

Accepted after revision: 20 April 2021

Accepted Manuscript online:
20 April 2021

Article published online:
25 May 2021

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