Mamoru Tobisu

Arene synthesis has been revolutionized by the invention of catalytic cross-coupling reactions, wherein aryl halides can be coupled with organometallic and organic nucleophiles. Although the replacement of aryl halides with phenol derivatives would lead to more economical and ecological methods, success has been primarily limited to activated phenol derivatives such as triflates. Aryl ethers arguably represent one of the most ideal substrates in terms of availability, cost, safety, and atom effi

To COMe and go: The title reaction, involving cleavage of a COMe bond, is demonstrated for the coupling of aryl methyl ethers on fused aromatic systems, such as naphthalene and phenanthrene, as well as anisoles containing electron-withdrawing groups with a wide range of boronic esters. cod=cycloocta-1,5-diene, Cy=cyclohexyl.

Two protocols for the nickel-catalyzed cross-coupling of aryl fluorides with aryl boronic esters have been developed. The first employs metal fluoride cocatalysts, such as ZrF(4) and TiF(4), which enable Suzuki-Miyaura reactions of aryl fluorides bearing electron-withdrawing (ketones, esters, and CF(3)), aryl and alkenyl groups as well as those comprising fused aromatic rings, such as fluoronaphthalenes and fluoroquinolines. The second protocol employs aryl fluorides bearing ortho-directing grou

The reaction of electron-deficient N-heteroaromatic compounds, such as pyridines and quinolines, with arylzinc reagents in the presence of a catalytic amount of a nickel complex affords the arylated products. The reaction is likely to proceed through a formal nucleophilic 1,2-addition, thus exhibiting a reactivity complementary to conventional direct arylation through electrophilic substitution.

Palladium-catalyzed ortho-alkynylation of aromatic C-H bonds in anilides is described. Preliminary mechanistic studies reveal that electrophilic palladation is involved. Synthetic elaborations of alkynylated products are also demonstrated.

Catalytic amination: The title reaction demonstrates the use of aryl carboxylates as suitable electrophilic coupling substrates in catalytic amination reactions. N-heterocyclic carbene ligands and NaOtBu promote the amination of aryl pivalates through the cleavage of normally unreactive aryl carbon-oxygen bonds (see scheme; cod=cyclooctadiene).

Access allowed: A Lewis acid catalyzed 1,5-hydride shift is the key step in the direct functionalization of sterically congested C(sp3)H bonds. This new method complements the existing transition-metal-mediated reactions that are limited to the functionalization of more accessible CH bonds.

Katalytische Aminierung: In der Titelreaktion werden Arylcarboxylate als elektrophile Kupplungspartner eingesetzt. N-heterocyclische Carbene als Liganden und NaOtBu erleichtern die Aminierung von Arylpivalaten unter Spaltung einer üblicherweise nichtreaktiven (Aryl)C-O-Bindung (siehe Schema).

Abstract Diaryliodonium salts have been used as aryl radical sources under visible light-mediated photoredox catalysis. Benzene and a range of heteroarenes are arylated with Ar2I+ in the presence of [Ir(ppy)2(bpy)]PF6 upon irradiation with visible light. When pyrroles are used, the arylation proceeds in the absence of a photoredox catalyst. Both processes are initiated by photoinduced single-electron-transfer to Ar2I+, generating aryl radicals.

The Rh(I)-catalyzed silylation of nitriles with disilanes is described. The cleavage of inert carbon-cyano and silicon-silicon bonds occurs in this catalysis.

The nickel-catalyzed reaction of N-aryl amides with hydroborane or diboron reagents resulted in the formation of the corresponding reduction or borylation products, respectively. Mechanistic studies revealed that these reactions proceeded via the activation of the C(aryl)-N bonds of simple, electronically neutral substrates and did not require the presence of an ortho directing group.

A rhodium-catalyzed silylation reaction of carbon-cyano bonds using disilane has been developed. Under these catalytic conditions, carbon-cyano bonds in aryl, alkenyl, allyl, and benzyl cyanides bearing a variety of functional groups can be silylated. The observation of an enamine side product in the silylation of benzyl cyanides and related stoichiometric studies indicate that the carbon-cyano bond cleavage proceeds through the deinsertion of silyl isocyanide from eta(2)-iminoacyl complex B. Kn

The reaction of aryl cyanides with diboron in the presence of a rhodium/Xantphos catalyst and DABCO affords arylboronic esters via carbon-cyano bond cleavage. This unprecedented mode of reactivity for a borylrhodium species allows the regioselective introduction of a boryl group in a late stage of synthesis.

Seeing the sites: The Suzuki-Miyaura reaction of substrates containing multiple coupling sites has been performed in a directed manner through the reactivity modulation of the boron moiety (see scheme). Several other strategies are also discussed.

Abstract Ni0-catalyzed cross-coupling of aryl methyl ethers with amines is described. The use of an N-heterocyclic carbene as a ligand and NaOt-Bu as a base promotes the amination of anisole derivatives via the cleavage of normally unreactive aryl carbon–oxygen bonds.