Metal‐Free Phosphorus‐Directed Borylation of C(sp²)−H Bonds

Abstract

Spectacular progress has recently been achieved in transition metal-catalyzed CÀHb orylation of phosphines as well as directed electrophilic CÀHb orylation. As shown here, P-directed electrophilic borylation provides anew,straightforward,a nd efficient access to phosphine-boranes.I to perates under metal-free conditions and leverages simple,r eadily available substrates.I ti sa pplicable to ab road range of backbones (naphthyl, biphenyl, N-phenylpyrrole,b inaphthyl, benzyl, naphthylmethyl) and gives facile access to various substitution patterns at boron (by varying the boron electrophile or post-derivatizing the borane moiety). NMR monitoring supports the involvement of P-stabilized borenium cations as key intermediates.DFT calculations reveal the existence and stabilizing effect of p-arene/boron interactions in the (biphenyl)(i-Pr) 2 P!BBr 2 + species.

Regioselective Transition‐Metal‐Free C(sp2)−H Borylation: A Subject of Practical and Ongoing Interest in Synthetic Organic Chemistry

“…Very recently, Bourissou and co-workers reported that a phosphine moiety serves as a directing group for the electrophilic borylation of a proximal CÀ H bond to give phosphine-boranes (Scheme 21a). [99] Various phosphines having different backbones, such as naphthyl (74), biphenyl (75), N-phenylpyrrole (76), benzyl (77), and naphthylmethyl (78), were applicable to the reaction. At nearly the same time, Wang, Shi, and co-workers also reported the same transformation (Scheme 21b).…”

“…Along with heterocycles, a phosphine moiety has also been used as an auxiliary for metal‐free directed C−H borylation. Very recently, Bourissou and co‐workers reported that a phosphine moiety serves as a directing group for the electrophilic borylation of a proximal C−H bond to give phosphine‐boranes (Scheme 21a) [99] . Various phosphines having different backbones, such as naphthyl ( 74 ), biphenyl ( 75 ), N ‐phenylpyrrole ( 76 ), benzyl ( 77 ), and naphthylmethyl ( 78 ), were applicable to the reaction.…”

Rhodium(I)-Catalyzed P(III)-Directed Aromatic C–H Acylation with Amides

“…Among various modification approaches, the C–H functionalization of simple biarylphosphines is often an efficient, atom- and step-economical strategy. Alkylation, alkenylation, , arylation, borylation, and silylation of biarylphosphines have been carried out in recent years. Despite achieving great success, further developing the methodology to extend ligand libraries and searching for alternative coupling partners are still highly desirable.…”

Facile synthesis and utilization of bis(o-phosphinophenyl)zinc as isolable PZnP-pincer ligands enabled by boron–zinc double transmetallation

“…Previously, we have developed the Ru-catalyzed ortho C–H borylation reaction of arylphosphines with HBpin to afford o -phosphinophenylboronic acid pinacol esters in high yields. 11,12 In our continuous research on the utilization of the borylation products, it was found that the treatment of ( o -diphenylphosphino)phenylboronate 1a with 1.0 equiv. of ZnEt 2 in toluene at room temperature afforded triphenylphosphine in 79% yield after acidic hydrolysis (Table 1, entry 1).…”