From Young Observers to Young Actors: A Message to IUPAC from a few Young Observers

International audienceFor many years, IUPAC has opened its doors to the younger chemists as observers to its activities, welcoming them in the midst of their General Assemblies. This is a unique opportunity for younger chemists to acquaint themselves with the work of the Divisions and Committees at an early stage and with limited commitment. In an article published in 2002, the Young Observers (YOs) program was characterized as “a way to seek innovative scientists” and “bring new expertise to IUPAC” [1]. Since 2013, the World Chemistry Leadership Meeting (WCLM) has invited all young observers to its symposium. In 2017, with a clever combination of “speed-networking” round tables, brainstorming and projects-crafting during the symposium, there is strong hope that a significant proportion of young observers will return as IUPAC active members during future meetings in Paris (2019) and Montréal (2021)

Iron-Catalyzed Regio- and Stereoselective Chlorosulfonylation of Terminal Alkynes with Aromatic Sulfonyl Chlorides

Terminal alkynes react with aromatic sulfonyl chlorides in the presence of an iron(II) catalyst and a phosphine ligand to give (<i>E</i>)-β-chlorovinylsulfones with 100% regio- and stereoselectivity. Various functional groups, such as chloride, bromide, iodide, nitro, ketone, and aldehyde, are tolerated under the reaction conditions. Addition of tosyl chloride to a 1,6-enyne followed by radical 5-<i>exo</i>-<i>trig</i> cyclization gave an exocyclic alkenylsulfone

Iron-Catalyzed Borylation of Aryl Chlorides in the Presence of Potassium <i>t</i>‑Butoxide

A catalytic amount of an inorganic iron salt such as Fe­(acac)₃ catalyzes borylation of various aryl and heteroaryl chlorides with bis­(pinacolato)­diboron, where the presence of potassium <i>t</i>-butoxide is crucially important. The alkoxide is considered to produce in situ an electron-rich iron alkoxide complex as the active species. The reaction requires only an iron salt and potassium <i>t</i>-butoxide as promoters and is easily scalable. The arylboron compound prepared by this reaction can be further coupled in situ with an aryl halide under the Suzuki–Miyaura conditions

Molybdenum/Quinone-Catalyzed Deoxygenative Coupling of Aromatic Carbonyl Compounds

A catalytic amount of Mo(CO)6 and an ortho-quinone ligand, in the presence of triphenylphosphine as a mild reductant enables the intermolecular reductive coupling of aromatic aldehydes and the intramolecular cou-pling of aromatic ketones to produce functionalized alkenes. Diaryl- and diheteroaryl alkenes are synthesized typically with high (E)-selectivity and with a tolerance of bromide, iodide, and steric hindrance. Intramolecular coupling of 1,6-diketones under similar conditions affords 9,10-disubstituted phenanthrenes

Nickel-Catalyzed Synthesis of Diarylamines via Oxidatively Induced C–N Bond Formation at Room Temperature

A nickel-catalyzed oxidative coupling of zinc amides with organomagnesium compounds selectively produces diarylamines under mild reaction conditions, with tolerance for chloride, bromide, hydroxyl, ester, and ketone groups. A diamine is bis-monoarylated. A bromoaniline undergoes <i>N</i>-arylation followed by Kumada–Tamao–Corriu coupling in one pot. The reaction may proceed via oxidatively induced reductive elimination of a nickel species

Iron-Catalyzed <i>Ortho</i> C–H Methylation of Aromatics Bearing a Simple Carbonyl Group with Methylaluminum and Tridentate Phosphine Ligand

Iron-catalyzed C–H functionalization of aromatics has attracted widespread attention from chemists in recent years, while the requirement of an elaborate directing group on the substrate has so far hampered the use of simple aromatic carbonyl compounds such as benzoic acid and ketones, much reducing its synthetic utility. We describe here a combination of a mildly reactive methylaluminum reagent and a new tridentate phosphine ligand for metal catalysis, 4-(bis­(2-(diphenyl­phosphanyl)­phenyl)­phosphanyl)-<i>N</i>,<i>N</i>-dimethyl­aniline (Me₂N-TP), that allows us to convert an <i>ortho</i> C–H bond to a C–CH₃ bond in aromatics and heteroaromatics bearing simple carbonyl groups under mild oxidative conditions. The reaction is powerful enough to methylate all four <i>ortho</i> C–H bonds in benzophenone. The reaction tolerates a variety of functional groups, such as boronic ester, halide, sulfide, heterocycles, and enolizable ketones

Iron-Catalyzed Chemo- and Stereoselective Hydromagnesiation of Diarylalkynes and Diynes

Diarylalkynes are chemo- and stereoselectively hydromagnesiated in high yields at room temperature with an iron species generated in situ from FeCl₂ and EtMgBr. Functional groups such as bromide, iodide, amine, phenoxide, and alkene are well tolerated. Under similar conditions, diynes are chemo-, regio-, and stereoselectively hydromagnesiated. The resulting alkenylmagnesium compounds are a platform for further functionalization as a one-pot reaction

Halogen–Sodium Exchange Revisited

Sodium is the most abundant alkali metal on Earth. Despite being an attractive choice for sustainable synthesis, organosodium compounds are rarely used in organic synthesis and have been overshadowed to date by organolithium compounds. This situation is largely due to the lack of convenient and efficient methods for the preparation of organosodium compounds. We report herein a halogen–sodium exchange method to prepare a large variety of (hetero)aryl- and alkenylsodium compounds, many of them previously inaccessible by other methods. The key discovery is the use of a bulky alkylsodium lacking a β-hydrogen, readily prepared in situ from neopentyl chloride and an easy-to-handle sodium dispersion, which retards undesired reactions such as Wurtz–Fittig coupling and β-hydrogen elimination, and enables efficient halogen-sodium exchange. We believe that the efficiency, generality, and convenience of the present method will open new horizons for the use of organosodium in organic synthesis, ultimately contributing to the development of sustainable chemistry by replacing the currently dominant organolithium reagents.</p

Iron-Catalyzed Directed C(sp²)–H and C(sp³)–H Functionalization with Trimethylaluminum

Conversion of a C­(sp²)–H or C­(sp³)–H bond to the corresponding C–Me bond can be achieved by using AlMe₃ or its air-stable diamine complex in the presence of catalytic amounts of an inorganic iron­(III) salt and a diphosphine along with 2,3-dichlorobutane as a stoichiometric oxidant. The reaction is applicable to a variety of amide substrates bearing a picolinoyl or 8-aminoquinolyl directing group, enabling methylation of a variety of (hetero)­aryl, alkenyl, and alkyl amides. The use of the mild aluminum reagent prevents undesired reduction of iron and allows the reaction to proceed with catalyst turnover numbers as high as 6500