Catalytic Borylation of SCF₃‐Functionalized Arenes by Rhodium(I) Boryl Complexes: Regioselective CH Activation at the ortho‐Position

Abstract

An unprecedented reaction pathway for the borylation of SCF3-containing arenes using [Rh(Bpin)(PEt3)3] (pin=pinacolato) is reported. Catalytic processes were developed and the functionalizations proceed under mild reaction conditions. The C-H activations occur with a unique regioselectivity for the position ortho to the SCF3 group, which apparently serves as directing group. Borylated SCF3 compounds can serve as versatile building blocks.

Efficient Rh-catalyzed C–H borylation of arene derivatives under photochemical conditions

“…Here, the low yield with HBpin may be a result of the strong oxygen-boron interaction resulting in deactivation of the rhodium catalyst. 16 However, CF 3 O-and CF 3 S-substituted arenes gave 75% and 78% yield, respectively of the desired products with HBpin (Table 2, entries 14b and 15b). Apparently, the presence of the strongly electron-withdrawing trifluromethyl group diminishes sulfur-boron and oxygen-boron interaction.…”

Suzuki–Miyaura Cross‐Coupling Reactions of Highly Fluorinated Arylboronic Esters: Catalytic Studies and Stoichiometric Model Reactions on the Transmetallation Step

“…The synthesis of 4‐BrC 6 H 4 CH 2 C{NHC(O)CH 3 }(CO 2 Et) 2 ( 2 b ) and 4‐BrC 6 H 4 CH 2 CH{NHC(O)CH 3 }CO 2 Et ( 2 a ) was done in accordance with the preparation by Ortwine, Malone et al., and Nishino et al . [Pd(Me) 2 (tmeda)] ( 7 , tmeda=tetramethylethylenediamine), [Pd(P i Pr 3 ) 2 ] ( 1 ), [Rh(Me)(PEt 3 ) 3 ], 2‐BpinC 5 NF 4 ( 4 ), 2‐BpinC 6 H 4 SCF 3 ( 8 b ), and i Pr 2 PCH 2 CH 2 CH 2 NMe 2 were synthesized in accordance with the literature. Column chromatography was performed on silica gel (Merck, Kieselgel 60).…”

“…It has been shown that highly fluorinated (hetero)cyclic boronic esters are accessible by C−H and C−X (X=F, Br or I) bond borylation, which is mediated by the boryl complex [Rh(Bpin)(PEt 3 ) 3 ] (pin=pinacolato=O 2 C 2 Me 4 ) or by the palladium(0) complex [Pd(P i Pr 3 ) 2 ] ( 1 ) . In this contribution, we report on the synthesis of 4‐aryl phenylalanine derivatives 5 a – b and 9 a – c , which contained aryl groups 2‐C 5 NF 4 , 4‐C 6 H 4 SF 5 , 2‐C 6 H 4 SCF 3 , and C 6 F 5 , by Suzuki–Miyaura cross‐coupling reactions.…”

Phosphorus‐Directed C−H Borylation

“…directing groups are well‐established through a variety of catalysts and ligand scaffolds [19,36,50–63] . Additional examples of silanes, thiol ethers, ethers, and halides are also reported [51,59,62,64–71] . Recently, phosphorus directing groups have been utilized to form both aryl and alkyl boronate esters, which will be the topic of this focused review.…”