Iron-Catalyzed Stereospecific Activation of Olefinic C–H Bonds with Grignard Reagent for Synthesis of Substituted Olefins

The reaction of an aryl Grignard reagent with a cyclic or acyclic olefin possessing a directing group such as pyridine or imine results in the stereospecific substitution of the olefinic C–H bond syn to the directing group. The reaction takes place smoothly and without isomerization of the product olefin in the presence of a mild oxidant (1,2-dichloro-2-methylpropane) and an aromatic cosolvent. Several lines of evidence suggest that the reaction proceeds via iron-catalyzed olefinic C–H bond activation rather than an oxidative Mizoroki–Heck-type reaction

Synthesis of Linear Allylsilanes via Molybdenum-Catalyzed Regioselective Hydrosilylation of Allenes

A simple molybdenum-based catalytic system for hydrosilylation of allenes has been developed. The reactions of mono- and disubstituted allenes with secondary and tertiary silanes proceeded smoothly and selectively to afford linear allylsilanes. The origin of the unprecedented linear selectivity was investigated by density functional theory studies to reveal that the reaction consists of the following steps: (1) concerted hydromolybdation/Si–H oxidative addition from a Mo­(CO)₄/allene/silane adduct to form (π-allyl)­molybdenum, (2) allyl rotation from the initially formed (π-allyl)­molybdenum to a thermodynamically more stable isomer, and (3) reductive elimination at the less-hindered allyl carbon to afford a linear allylsilane

Iron-Catalyzed <i>Ortho</i>-Allylation of Aromatic Carboxamides with Allyl Ethers

Arenes possessing an <i>N</i>-(quinolin-8-yl)­amide directing group are <i>ortho</i>-allylated with allyl phenyl ether in the presence of an iron/diphosphine catalyst and an organometallic base at 50–70 °C. The reaction proceeds via fast iron-catalyzed C–H activation, followed by reaction of the resulting iron intermediate with the allyl ether in γ-selective fashion

Deoxygenative Insertion of Carbonyl Carbon into a C(sp³)–H Bond: Synthesis of Indolines and Indoles

A simple deoxygenation reagent prepared in situ from commercially available Mo­(CO)6 and ortho-quinone has been developed for the synthesis of indoline and indole derivatives. The Mo/quinone complex efficiently deoxygenates carbonyl compounds bearing a neighboring dialkylamino group and effects intramolecular cyclizations with the insertion of a deoxygenated carbonyl carbon into a C­(sp3)–H bond, in which a carbonyl group acts as a carbene equivalent. The reaction also proceeds with a catalytic amount of Mo/quinone in the presence of disilane as an oxygen atom acceptor

Iron-Catalyzed C(sp²)–H Bond Functionalization with Organoboron Compounds

We report here that an iron-catalyzed directed C–H functionalization reaction allows the coupling of a variety of aromatic, heteroaromatic, and olefinic substrates with alkenyl and aryl boron compounds under mild oxidative conditions. We rationalize these results by the involvement of an organoiron­(III) reactive intermediate that is responsible for the C–H bond-activation process. A zinc salt is crucial to promote the transfer of the organic group from the boron atom to the iron­(III) atom

Synthesis of Anthranilic Acid Derivatives through Iron-Catalyzed Ortho Amination of Aromatic Carboxamides with <i>N</i>‑Chloroamines

Arenes possessing an 8-quinolinylamide group as a directing group are ortho aminated with <i>N</i>-chloroamines and <i>N</i>-benzoyloxyamines in the presence of an iron/diphosphine catalyst and an organometallic base to produce anthranilic acid derivatives in high yield. The reaction proceeds via iron-catalyzed C–H activation, followed by the reaction of the resulting iron intermediate with <i>N</i>-chloroamine. The choice of the directing group and diphosphine ligand is crucial for obtaining the anthranilic acid derivative with high yield and product selectivity

Iron-Catalyzed Directed Alkylation of Aromatic and Olefinic Carboxamides with Primary and Secondary Alkyl Tosylates, Mesylates, and Halides

Alkenes, arenes, and heteroarenes possessing an 8-quinolylamide group as the directing group are alkylated with primary and secondary alkyl tosylates, mesylate, and halides in the presence of Fe­(acac)₃/diphosphine as a catalyst and ArZnBr as a base. The reaction proceeds stereospecifically for alkene substrates and takes place without loss of regiochemical integrity of the starting secondary tosylate, but with loss of the stereochemistry of the chiral center

Molybdenum–Quinone-Catalyzed Deoxygenative Coupling of Aromatic Carbonyl Compounds

In the presence of triphenylphosphine as a mild reductant, the use of catalytic amounts of Mo­(CO)6 and an ortho-quinone ligand enables the intermolecular reductive coupling of aromatic aldehydes and the intramolecular coupling of aromatic ketones to produce functionalized alkenes. Diaryl- and diheteroaryl alkenes are synthesized with high (E)-selectivity and a tolerance toward bromide, iodide, and steric hindrance. Intramolecular coupling of dicarbonyl compounds under similar conditions affords mono- and disubstituted phenanthrenes