7 research outputs found
IridiumâCatalysed CâH Borylation of Fluoroarenes: Insights into the Balance between Steric and Electronic Control of Regioselectivity
The iridium catalysed CâH borylation of polyfluorinated arenes and heteroarenes occurs rapidly and efficiently. As with other borylation reactions, whilst steric parameters dominate, an underlying electronic influence on reaction selectivity can be observed. Notably borylation regioselectivity in fluorinated (hetero)arenes is determined by purely electronic effects except for ortho-borylation between two fluorine atoms where steric effects of fluorine substituents become apparent. Borylation at the para position with respect to fluorine is disfavoured whereas a strong electronic preference for borylation para to the azinyl nitrogen of pyridine is observed. When these features co-operate high selectivity can be expected. For these reactions, computations based on transition state, rather than intermediate, energies in iridium geometries showed excellent agreement between predicted and observed selectivities
The Earth: Plasma Sources, Losses, and Transport Processes
This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed
Multidirectional Synthesis of Substituted Indazoles via Iridium-Catalyzed C-H Borylation
In the absence of a steric directing group, iridium-catalyzed CâH borylation of N-protected indazoles occurs rapidly and selectively at C-3 and the resulting boronate esters can be utilized in a range of downstream conversions. The functional group tolerance of the iridium-catalyzed CâH borylation reaction enables simple and efficient multidirectional syntheses of substituted indazoles to be realized
The Earth: Plasma Sources, Losses, and Transport Processes
International audienceThis paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed