Recent developments in alkyne borylations.
Résumé
Within the past few decades, organoboron derivatives have become essential intermediates in organic and medicinal chemistry. As a matter of fact, while boronic acids have found wide applications as saccharide sensors1, 2 and 3 self-organizing systems,4, 5, 6 and 7 and medicine,8, 9 and 10 the unique reactivity of the C–B bond has profoundly affected the way organic chemists foresee the construction of carbon–carbon bonds. The contribution of organoboron chemistry to organic chemistry was recognized with two Nobel Prizes awarded in 1979 to Herbert C. Brown and in 2010 to Akira Suzuki who both instigated the development of new synthetic tools for the introduction of boron atoms into organic molecules. Of particular interest are vinylboron species due to their importance in a wide range of applications in natural product total synthesis.11 The stereocontrol of the new carbon–carbon bond is also of high significance. Whereas uncatalyzed and catalyzed processes have already been reviewed in the past,12, 13 and 14 the present report covers mostly recent developments published in the past ten years in the field of metal-free direct and transition metal-catalyzed synthesis of mono-, bis- and metallo-boronate compounds starting from alkynes.13 The mechanistic features and the stereochemical outcome (E/Z nomenclature) will be discussed as well.