Advances in silylation and borylation of fluoroarenes and gem-difluoroalkenes via C–F bond cleavage

Abstract

Organoboron and organosilane compounds are widely used in organic synthesis and pharmaceuticals. In addition, the C-F bond functionalization is a useful tool for the construction of carbon-carbon and carbon-heteroatom bonds....

Recent Advances in Alkenyl sp2 C–H and C–F Bond Functionalizations: Scope, Mechanism, and Applications

“…Accordingly, there have been considerable efforts toward the development of broadly applicable methods to prepare this extremely important class of compounds. The direct alkenyl C–F bond functionalization of gem -difluoroalkenes undoubtedly offers a practical and unique tool for the synthesis of fluorinated alkenyl borons and silanes, which could also act as versatile building blocks for further elaborations to synthesize value-added complex molecules . In 2017, Cao and colleagues continued their C–F bond functionalization strategy and described the first example of copper-catalyzed stereoselective C–F bond borylation of gem -difluoroalkenes with bis(pinacolato)diboron (B 2 pin 2 ) in the presence of NaO t Bu base and Xantphos ligand at room temperature, enabling a convenient synthesis of structurally diverse ( Z )-fluorinated alkenylboronic pinacol esters in 51–81% yields (Scheme ).…”

C−F Bond Activation and Functionalizations Enabled by Metal‐free NHCs and Their Metal Complexes

“…[12,13] To complement these functionalities, concomitant formation of thermodynamic sinks such as HF, R 3 SiF, or BF 4 À were observed. Generally, cleavage of the CÀ F was effected by using metal complexes [14,15] (metallocenes, [1,[16][17][18][19][20] metal-phosphines, [7,[21][22][23][24][25][26] metal-carbonyls, [4,6,23] metal-NHCs, [27,28] and rare earth metals [29,30] ), strong Brønsted acids (such as hydrogen halides), strong Lewis acids [31] (such as aluminum, [3,9] boron, carbocation, and silylation compounds [15,32] ) and photocatalysis. [9] In the case of metal complexes, both stoichiometric and catalytic conversions were achieved, where the former transformation assisted in understanding the key steps involved in the catalytic cycle.…”

Synthesis of Tri‐ and Tetrasubstituted Alkenyl Boronates from Alkynes

“…In this review, we will focus on the synthesis of tri‐ and tetrasubstituted alkenyl boronates by hydroboration, carboboration or elementoboration of alkynes. Other strategies to produce tri‐ or tetrasubstituted alkenylboronates, which use allenes, alkenes (dehydrogenative [9] or defluorinative [10] borylation), aldehydes/ketones (Boron‐Wittig olefination [11] ) as starting materials or the isomerization of alkenyl boronates, [12] will not be covered. All transformations involving polyboronates will be omitted since this topic has been conveniently reviewed [13]…”