Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

Abstract

Numerous reactions generating C-Si and C-B bonds are in focus owing to the importance of incorporating silicon or boron into new or existing drugs, in addition to their use as building blocks in cross-coupling reactions en route to various targets of both natural and unnatural origins. In this review, recent protocols relying on copper-catalyzed sp 3 carbon-silicon and carbon-boron bond-forming reactions are discussed. 691

Beyond Carbon: Enantioselective and Enantiospecific Reactions with Catalytically Generated Boryl- and Silylcopper Intermediates

“…The first two decades of the 21st century have witnessed tremendous advances in using catalytically generated Cu–B and Cu–Si intermediates in asymmetric reactions. The progress made in this promising field is evident from the large body of cited literature. − The area evolved from two-component, such as addition and allylic substitution reactions, to multi-component transformations, which allow for the construction of more than one chiral center in a single synthetic operation while at the same time installing a transformable boryl or silyl group.…”

“…Copper-catalyzed asymmetric transformations featuring excellent stereo­control and broad functional-group tolerance are arguably an important part of modern organic synthesis. Accordingly, considerable advances have been made to forge not only C–C but also C–Het bonds by enantio­controlled copper catalysis, − and methods to incorporate main-group elements such as boron − and silicon − into carbon frameworks have witnessed steady growth over the past two decades (Figure ). These developments have also been driven by an increasing demand for boron- and silicon-containing molecules with attractive chemical and physical properties in medicinal chemistry and material science (Figure ).…”

“…There are elegant copper-catalyzed asymmetric C–B and C–Si bond-forming reactions employing hydroboranes and hydrosilanes, such as carbene insertion − as well as hydroboration , and hydrosilylation, where the boron and silicon centers are electrophilic . Nonetheless, the vast majority of methods rely on the use of boron and silicon nucleophiles, in which nucleophilic L*Cu–B ( I ) and L*Cu–Si ( II ) intermediates are formed. − In 2000, the seminal applications of the boryl­copper intermediate derived from B–B reagents in conjugate addition were independently disclosed by Hosomi and Miyaura. , Similar transmetalation approaches to generate silyl­copper intermediates were introduced by Hosomi for Si–Si reagents , and by Hoveyda, Oestreich, and Riant for Si–B reagents. − With respect to silyl­copper complexes, there had been a rich chemistry, initially stoichiometric in copper but later catalytic with zinc- and magnesium-based , silicon nucleophiles . Of known boron and silicon (pro)­nucleophiles, the widespread use of currently commercially available and storable B–B and Si–B compounds, e.g., B 2 pin 2 ( 1 ) and Me 2 PhSiBpin ( 2 ), in asymmetric copper catalysis clearly stands out.…”

“…Copper-catalyzed C–B and C–Si bond-forming reactions have been covered in previous reviews. − This Outlook is meant not to simply repeat or update those reviews but instead to emphasize the different strategies to apply Cu–B and Cu–Si intermediates to enantio­selective and enantio­specific transformations: (i) addition reactions, (ii) allylic substitution reactions, (iii) three-component reactions, and (iv) cross-coupling reactions.…”

Photoinduced Borylation for the Synthesis of Organoboron Compounds

“…The development of practical and convenient ways to synthesize boronate esters has gained increasing interest over the past few decades. The classical method for the preparation of boronic acids is using highly reactive organolithium or Grignard reagents in combination with suitable boron precursors followed by transesterification or hydrolysis. , Recently, a series of new borylation protocols, including transition-metal-catalyzed hydroborations and diborations of alkenes and alkynes, ,− C–H ,− and C–X − borylations, which display a high degree of functional group tolerance, transition-metal-free borylations, , and so on have been developed to achieve the borylation of different classes of organic compounds.…”