Two novel frustrated Lewis pair (FLP) aminoboranes, (1-Pip-2-BH-CH) (2; Pip = piperidyl) and (1-NEt-2-BH-CH) (3; NEt = diethylamino), were synthesized, and their structural features were elucidated both in solution and in the solid state. The reactivity of these species for the borylation of heteroarenes was investigated and compared to previously reported (1-TMP-2-BH-CH) (1; TMP = tetramethylpiperidyl) and (1-NMe-2-BH-CH) (4; NMe = dimethylamino). It was shown that 2 and 3 are more active catalysts for the borylation of heteroarenes than the bulkier analogue 1. Kinetic studies and density functional theory calculations were performed with 1 and 2 to ascertain the influence of the amino group of this FLP-catalyzed transformation. The C-H activation step was found to be more facile with smaller amines at the expense of a more difficult dissociation of the dimeric species. The bench-stable fluoroborate salts of all catalysts (1F-4F) have been synthesized and tested for the borylation reaction. The new precatalysts 2F and 3F are showing higher reaction rates and yields for multigram-scale syntheses.

C−C reductive elimination from [PdL 2 (C 6 F 5 ) 2 ] to form polyfluorinated biaryls has been a challenge for over 50 years. Thus, palladium-catalyzed homocoupling of arylboronates (Ar F − Bpin) containing two ortho-fluorine substituents is very difficult, as the reaction typically stops at the [PdL 2 (Ar F ) 2 ] stage after two transmetalation steps. The transmetalated complexes cis-[Pd-and cis-[Pd(MeCN) 2 (2,6-C 6 F 2 H 3 ) 2 ] (3e) have been isolated from the reaction of Ar F −Bpin with Pd(OAc) 2 in acetonitrile solvent, with no homocoupling observed. However, catalytic homocoupling proceeds smoothly in a "weakly coordinating" arene solvent as long as no ancillary ligands or coordinating solvents are present. DFT computations reveal that the active catalyst formed by arene solvent coordination leads to an overall reduced barrier for the reductive elimination step compared to the formation of stable [PdL 2 (Ar F ) 2 ] complexes in the presence of a donor ligand or solvent L.

While a stable base-free arylalumylene bearing a sterically encumbered terphenyl substituent has been reported previously, we herein report that our attempts to form a base-stabilised arylalumylene bearing a relatively small...

The complex [W(CO) 5 {PClPh 2 }] reacts with AlCl 3 to form a mixture of the phosphenium complex [W(CO) 5 {PPh 2 }][AlCl 4 ] and an isocarbonyl, with GaCl 3 to form [W(CO) 5 {PPh 2 }][GaCl 4 ], and with silver trifluoromethanesulfonate to form [W(CO) 5 {P(OSO 2 CF 3 )Ph 2 }]. All three complexes react as strong P electrophiles, undergoing electrophilic substitution reactions with aromatic and heteroaromatic compounds, alkenes, and alkynes, to form aromatic and heteroaromatic phosphines, allyl phosphines, and alkynyl phosphines, respectively. Alkenes lacking cleavable γ-H atoms and internal alkynes undergo tandem electrophilic addition/substitution reactions, adding between the P and one of the phenyl rings to form fused P heterocycles. The newly formed phosphines can be removed from the tungsten complex by photolysis in the presence of bis(diphenylphosphino)ethane.

We report the first example of catalytic dearomatization of indoles to generate 3-borylindolines using metal-free borane catalysts.

In the presence of chloride abstractors, metal-coordinated chlorophosphines undergo facile room-temperature electrophilic substitution reactions with unsaturated organic substrates, leading to P-C bond formation. This methodology can be applied sequentially two or three times, stepwise or in one-pot reactions, to form phosphines with three different substituents. The reactions are rapid and high-yielding, and can be applied to a wide range of organic substrates, making them valuable tools for P-C bond formation.

A practical and scalable metal-free catalytic method for the borylation and borylative dearomatization of heteroarenes has been developed. This synthetic method uses inexpensive and conveniently synthesizable bench-stable precatalysts of the form 1-NHR2-2-BF3-C6H4, commercially and synthetically accessible heteroarenes as substrates, and pinacolborane as borylation reagent. Preparation of several borylated heterocycles in 2 and 50 grams was achieved under solvent-free conditions without the use of Schlenk techniques or a glove box. A kilogram-scale borylation of one of the heteroarene substrates was also achieved using this cost-effective green methodology to exemplify the fact that our methodology can be conveniently implemented in fine chemical industries.

Reaction of K 2 [W(CO) 5 ] with Cl 2 PN-i-Pr 2 in the presence of diphenylacetylene leads to the tungsten aminophosphirene complex [W(CO) 5 {P(N-i-Pr 2 )C(Ph)C-(Ph)}] (1), which can be converted to the chlorophosphirene complex [W(CO) 5 {P(Cl)C(Ph)C(Ph)}] (2) by reaction with HCl. Chloride abstraction from 2 with excess AlCl 3 leads to the tungsten-complexed phosphirenyl cation [W(CO) 5 {PC-(Ph)C(Ph)}][AlCl 4 ] ( 3). Compound 3 reacts with PPh 3 to form a phosphoniophosphirene complex and undergoes electrophilic aromatic substitution with ferrocene to form a ferrocenylphosphirene complex. Chloride abstraction from 2 with silver triflate leads to a phosphirenyl triflate complex, which reacts with PPh 3 and ferrocene in the same fashion as 3 but also reacts cleanly with a wider range of substrates, including phenylacetylene and allyltrimethylsilane, to form respectively a phenylalkynylphosphirene complex and an allylphosphirene complex.