We report the oxidative dimerization reaction of siloxydienes derived from simple enones that creates a new gamma‐gamma (γ‐γ) C−C bond using catalytic iron and benzoyl peroxide as the terminal oxidant in acetonitrile solvent at ambient temperature. The reaction shows a broad substrate scope including cyclic and acyclic siloxydienes derived from ketones, aldehydes, and esters, which are converted to 1,8‐dicarbonyl compounds under mild catalytic reaction conditions in 19–89 % yield across 30 examples. The method is suitable for the coupling of sterically demanding carbon centers, including the formation of vicinal quaternary centers. Conceptually, the dienol ether serves as a precursor to a conjugated radical cation, which undergoes highly site selective γ‐dimerization reactions. The γ‐γ dimerization strategy is applied to the synthesis of a bioactive analogue of honokiol.
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Abstract -
One of the challenges in direct conversion Doppler radar lies in the dc offset resulted from antenna coupling. The dc offset may saturate the baseband amplifiers, preventing sufficient amplification of the received signal. In this work, a Coupling-Cancellation-Antenna (CCA) was implemented in the radar front end to enhance radar detection accuracy by minimizing the TX-RX antenna coupling. The idea is to have two transmitting antennas fed by signals with 180° phase difference such that the two signals cancel at the RX antenna. As a result, a larger receiver gain can be used to improve the signal to noise ratio without saturating the baseband output. Experimental validations of the CCA concept demonstrate 37-dB reduction in the TX-RX coupling. Furthermore, the CCA method reduces the detection error from 15.8% to 2.4%.more » « less
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Contact-based cardiac motion detection using Quadrature Doppler radar faces a challenge of the I/Q-formed non-arc constellation. In this work, a hypothesis is brought forward that such complicated constellation originates from not one, but two moving targets. The dual-motion model may very well explain that contact-based Doppler radar detects both atrium and ventricle motions during cardiac cycles. In this work, dual-motion simulation and phantom measurements are presented, verifying that the atrial-ventricular motions are the reason that I/Q baseband signals transcribe a complex non-arc constellation. It offers the first evidence that contact-based Doppler radar measures actual heart motion.more » « less
