1,013 research outputs found
Ruthenium‐Catalyzed Remote‐Difunctionalization of Nonactivated Alkenes for Double meta‐C(sp2)−H/C‐6(sp3)−H Functionalization
No full textTwofold distal C−H functionalization was accomplished by difunctionalization of nonactivated alkenes to provide rapid access to multifunctionalized molecules. The multicomponent ruthenium-catalyzed remote 1,n-difunctionalization (n=6,7) of nonactivated alkenes with fluoroalkyl halides and heteroarenes in a modular manner is reported. The meta-C(sp2)−H/C-6(sp3)−H distal functionalization featured mild conditions, unique selectivity, and broad substrate scope with a domino process for twofold remote C(sp2)−H/C(sp3)−H activation of the sequential formation of three different carbon-centered radicals. A plausible mechanism was proposed based on detailed experimental and computational studies.European Research Council http://dx.doi.org/10.13039/501100000781DFG http://dx.doi.org/10.13039/501100001659Alexander von Humboldt-Stiftung http://dx.doi.org/10.13039/100005156China Sponsorship Council http://dx.doi.org/10.13039/50110000454
)−H‐Funktionalisierung
No full textAbstract Die zweifache distale C−H‐Funktionalisierung wurde durch Difunktionalisierung von nicht aktivierten Alkenen erreicht, um einen schnellen Zugang zu hochfunktionalisierten Molekülen zu ermöglichen. Wir berichten hier über die Mehrkomponten‐Ruthenium‐katalysierte 1,n‐Ferndifunktionalisierung ( n =6,7) von nicht aktivierten Alkenen mit Fluoralkylhalogeniden und Heteroarenen in modularer Weise. Die distale meta ‐C(sp 2 )−H/C‐6(sp 3 )−H‐Funktionalisierung zeichnete sich durch milde Bedingungen, einzigartige Selektivität und einen breiten Substratbereich mit einem Domino‐Prozess für die zweifache C(sp 2 )−H/C(sp 3 )−H‐Fernaktivierung der sequentiellen Bildung von drei verschiedenen kohlenstoff‐zentrierten Radikalen aus. Auf der Grundlage detaillierter experimenteller und rechnerischer Studien wurde ein plausibler Mechanismus vorgeschlagen.European Research Council https://doi.org/10.13039/501100000781Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659Alexander von Humboldt-Stiftung https://doi.org/10.13039/100005156China Scholarship Council https://doi.org/10.13039/50110000454
Elektrooxidative Rhodium‐katalysierte [5+2]‐Anellierung durch C‐H/O‐H‐Aktivierung
No full textDFG http://dx.doi.org/10.13039/501100001659Alexander von Humboldt-Stiftung http://dx.doi.org/10.13039/100005156China Sponsorship Council (CN
Photo‐Induced Ruthenium‐Catalyzed Double Remote C(sp(2))−H / C(sp(3))−H Functionalizations by Radical Relay
No full textDistal C(sp(2))−H and C(sp(3))−H functionalizations have recently emerged as step‐economical tools for molecular synthesis. However, while the C(sp(2))−C(sp(3)) construction is of fundamental importance, its formation through double remote C(sp(2))−H/C(sp(3))−H activation has proven elusive. By merging the ruthenium‐catalyzed meta‐C(sp(2))−H functionalization with an aliphatic hydrogen atom transfer (HAT) process, we, herein, describe the catalyzed twofold remote C(sp(2))−H/C(sp(3))−H functionalizations via photo‐induced ruthenium‐mediated radical relay. Thus, meta‐C(sp(2))−H arene bonds and remote C(sp(3))−H alkane bonds were activated by a single catalyst in a single operation. This process was accomplished at room temperature by visible light—notably without exogenous photocatalysts. Experimental and computational theory studies uncovered a manifold comprising ortho‐C−H activation, single‐electron‐transfer (SET), 1,n‐HAT (n=5–7) and σ‐activation by means of a single ruthenium(II) catalyst
Ruthenaphoto-catalyzed ortho-C−H alkylation with secondary alkyl halides: SET-enabled ruthenium(II/III/IV) manifold
No full texthttp://dx.doi.org/10.13039/100019180 HORIZON EUROPE European Research Councilhttp://dx.doi.org/10.13039/501100001659 German Research Foundationhttp://dx.doi.org/10.13039/501100004543 China Scholarship Councilhttp://dx.doi.org/10.13039/501100000781 European Research Councilhttp://dx.doi.org/10.13039/100005156 Alexander von Humboldt-Stiftun
Acoustic Localization System for Precise Drone Landing
Full text linkWe present MICNEST: an acoustic localization system enabling precise drone landing. In MICNEST, multiple microphones are deployed on a landing platform in carefully devised configurations. The drone carries a speaker transmitting purposefully-designed acoustic pulses. The drone may be localized as long as the pulses are correctly detected. Doing so is challenging: i) because of limited transmission power, propagation attenuation, background noise, and propeller interference, the Signal-to-Noise Ratio (SNR) of received pulses is intrinsically low; ii) the pulses experience non-linear Doppler distortion due to the physical drone dynamics; iii) as location information is used during landing, the processing latency must be reduced to effectively feed the flight control loop. To tackle these issues, we design a novel pulse detector, Matched Filter Tree (MFT), whose idea is to convert pulse detection to a tree search problem. We further present three practical methods to accelerate tree search jointly. Our experiments show that MICNEST can localize a drone 120 m away with 0.53% relative localization error at 20 Hz location update frequency. For navigating drone landing, MICNEST can achieve a success rate of 94 %. The average landing error (distance between landing point and target point) is only 4.3 cm
‐C−H Bromination with Aqueous HBr
No full textWhile electrochemical ortho‐selective C−H activations are well established, distal C−H activations continue to be underdeveloped. In contrast, we herein describe the electrochemical meta‐C−H functionalization. The remote C−H bromination was accomplished in an undivided cell by RuCl(3)⋅3 H(2)O with aqueous HBr. The electrohalogenation proceeded under exogenous ligand‐ and electrolyte‐free conditions. Notably, pyrazolylarenes were meta‐selectively brominated at the benzenoid moiety, rather than on the electron‐rich pyrazole ring for the first time. Mechanistic studies were suggestive of an initial ruthenacycle formation, and a subsequent ligand‐to‐ligand hydrogen transfer (LLHT) process to liberate the brominated product
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