Rhenium-catalyzed insertion of terminal alkenes into a C(sp(2))–H bond and successive transfer hydrogenation

Treatment of aromatic aldimines with terminal alkenes in the presence of a rhenium catalyst, [HRe(CO)(4)](n), gives 2-alkenylbenzylamines in good to excellent yields. This reaction proceeds via the insertion of the alkene into a C-H bond at the ortho-position of the imino group of the aromatic aldimine followed by sequential beta-hydride elimination from the formed alkyl rhenium intermediate and then by hydrogenation of the imino group of the aldimine

Photoinduced Deaminative Borylation of Unactivated Aromatic Amines Enhanced by CO2

Herein, direct unactivated C-N borylation of aromatic amines by a photocatalyst was achieved under mild and metal-free conditions. The C-N borylation of aromatic amines with bis(pinacolato)diboron (B2pin2) proceeded in the presence of a pyrene catalyst under light irradiation (λ = 365 nm) to afford desired borylated products and aminoborane as a byproduct. The yield of borylated product improved under a CO2 atmosphere. Reactions conducted in the presence of a stoichiometric amount of aminoborane under N2 or CO2 indicated that CO2 reduced the inhibitory effect of aminoborane. Optimal reaction conditions were applied to a variety of aromatic amines. Mechanistic studies suggested that the C-N bond cleavage and C-B bond formation proceeded via a concerted pathway

3-Position-Selective C–H Trifluoromethylation of Pyridine Rings Based on Nucleophilic Activation

The first example of the 3-position-selective C(sp2)–H trifluoromethylation of pyridine rings was established. 3-Position-selective trifluoromethylation was achieved by the nucleophilic activation of pyridine and quinoline derivatives through hydrosilylation and successive electrophilic trifluoromethylation of the enamine intermediate. This reaction was applicable to perfluoroalkylation at the 3-position of the pyridine rings and late-stage trifluoromethylation of a bioactive molecule. Mechanistic studies indicated that the reaction proceeds via the formation of N-silyl enamine and trifluoromethylated enamine intermediates

Iron-Catalyzed <i>ortho</i>-Selective C–H Borylation of 2‑Phenylpyridines and Their Analogs

Treatment of 2-phenylpyridines (or their analogs) with a 9-bicyclo­boranonane dimer (9-BBN dimer) in the presence of a catalytic amount of a commercially available iron salt, FeBr₃, gave <i>ortho</i>-borylated products in moderate to excellent yields with good functional group tolerance. The reaction proceeded in good yield, even in gram-scale, and also occurred at the C–H bond of heteroaromatic compounds. The cost of the C–H borylation is dramatically lower than that of a previously reported similar palladium-catalyzed reaction. The products exhibit an intramolecular B–N Lewis acid–base interaction and fluoresce in both solution and solid states due to their electron push–pull structures

Copper-Catalyzed <i>N</i>- and <i>O</i>‑Alkylation of Amines and Phenols using Alkylborane Reagents

By the reaction of amines with alkylborane reagents in the presence of a catalytic amount of copper(II) acetate Cu(OAc)₂ and di-<i>tert</i>-butyl peroxide, a cross-coupling reaction proceeded and alkylated amines were obtained in good to excellent yields. Phenols are also applicable for this reaction, and the corresponding alkyl aryl ethers were produced

Rhenium-Catalyzed Insertion of Terminal Alkenes into a C(sp 2 )-H Bond and Successive Transfer Hydrogenation

Abstract Treatment of aromatic aldimines with terminal alkenes in the presence of a rhenium catalyst, [HRe(CO) 4 ] n , gives 2-alkenylbenzylamines in good to excellent yields. This reaction proceeds via the insertion of the alkene into a C-H bond at the ortho-position of the imino group of the aromatic aldimine followed by sequential β-hydride elimination from the formed alkyl rhenium intermediate and then by hydrogenation of the imino group of the aldimine

Copper-Catalyzed C–H Alkoxylation of Azoles

We achieved copper-catalyzed intramolecular and intermolecular alkoxylation of azoles. This reaction is a rare example of transition-metal-catalyzed C–H alkoxylation of heteroaromatic compounds. In addition, the alkoxylation reaction proceeded well even in gram scale. In most intermolecular alkoxylations, the use of an excess amount of alcohols (in some cases, alcohols are used as a solvent) is indispensable to efficiently promote the alkoxylation reaction, but this alkoxylation reaction proceeded using only 1 equiv of alcohols

Rhenium-Catalyzed Regio- and Stereoselective Synthesis of γ‑Thio-α,β-unsaturated Ketones via Insertion of Terminal Alkynes into the C–S Bond

The reaction of α-thioketones and alkynes in the presence of a rhenium catalyst, [HRe(CO)₄]_<i>n</i>, gave γ-thio-α,β-unsaturated ketones in excellent yields. The alkynes were inserted into the carbon–sulfur bond of the α-thioketones, and isomerization of a double bond provided the products with high regio- and stereoselectivities. This reaction also proceeded in an intramolecular fashion