Rhodium(III)-Catalyzed Cyclopropanation of Unactivated Olefins Initiated by C–H Activation

We have developed a rhodium(III)-catalyzed cyclopropanation of unactivated olefins initiated by an alkenyl C–H activation. A variety of 1,1-disubstituted olefins undergo efficient cyclopropanation with a slight excess of alkene stoichiometry. A series of mechanistic interrogations implicate a metal carbene as an intermediate.</jats:p

MIRS: MMX Infrared Spectrometer to Martian System

International audienceMIRS is an imaging spectrometer (working in the spectral range 0.9–3.6 µm) onboard the JAXA sample return MMX (Martian Moon eXploration) mission. The objectives of the mission are to study the origin of martian moons and to enlarge the knowledge of the martian system

MIRS: MMX Infrared Spectrometer to Martian System

International audienceMIRS is an imaging spectrometer (working in the spectral range 0.9–3.6 µm) onboard the JAXA sample return MMX (Martian Moon eXploration) mission. The objectives of the mission are to study the origin of martian moons and to enlarge the knowledge of the martian system

A site-selective amination catalyst discriminates between nearly identical C–H bonds of unsymmetrical disubstituted alkenes

C−H activation reactions enable chemists to unveil new retrosynthetic disconnections and streamline conventional synthetic approaches. A longstanding challenge in C−H activation is the inability to distinguish electronically and sterically similar C–H bonds. Although numerous synergistic combinations of transition-metal complexes and chelating directing groups have been utilized to distinguish C−H bonds, undirected regioselective C−H functionalization strategies remain elusive. Herein, we report a regioselective C−H activation/amination reaction of various unsymmetrical dialkyl-substituted alkenes. The regioselectivity of C−H activation is correlated to the electronic properties of allylic C−H bonds indicated by the corresponding 1JCH coupling constants. A linear relationship between the difference of 1JCH coupling constants of the two competing allylic C−H bonds (Δ 1JCH) and the C−H activation barriers (Δ ΔG ‡ ) has also been determined

MIRS: MMX Infrared Spectrometer to Martian System

International audienceMIRS is an imaging spectrometer (working in the spectral range 0.9–3.6 µm) onboard the JAXA sample return MMX (Martian Moon eXploration) mission. The objectives of the mission are to study the origin of martian moons and to enlarge the knowledge of the martian system

MIRS: An infrared spectro-imager aboard the Martian Moon eXploration mission to study Phobos, Deimos

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