The activated alkynes
have been used successfully for the first time as the dipolarophile
in the palladium-catalyzed asymmetric (3 + 2) cycloaddition, affording
highly functionalized cyclopentenes in good to high yields with high
chemoselectivities and good to high enantioselectivities. The introduction
of an additional carbonyl group at the α-position of the alkynyl
esters is the key to activating the carbon–carbon triple bond.
The reaction process was investigated, and an inverse process of Pd-catalyzed
(3 + 2) cycloaddition was observed.
Diastereo- and enantioselective construction of vicinal tertiary and quaternary carbon centers is a great challenge in synthetic chemistry. Herein, we report a facile and efficient protocol to construct vicinal tertiary...
In recent years, global automotive industries are going through a significant revolution from traditional internal combustion engine vehicles (ICEVs) to electric vehicles (EVs) for CO2 emission reduction. Very similarly, the aviation industry is developing towards more electric aircraft (MEA) in response to the reduction in global CO2 emission. To promote this technology revolution and performance advancement, plenty of electronic devices with high heat flux are implemented on board automobiles and aircraft. To cope with the thermal challenges of electronics, in addition to developing wide bandgap (WBG) semiconductors with satisfactory electric and thermal performance, providing proper thermal management solutions may be a much more cost-effective way at present. This paper provides an overview of the thermal management technologies for electronics used in automobiles and aircraft. Meanwhile, the active methods include forced air cooling, indirect contact cold plate cooling, direct contact baseplate cooling, jet impingement, spray cooling, and so on. The passive methods include the use of various heat pipes and PCMs. The features, thermal performance, and development tendency of these active and passive thermal management technologies are reviewed in detail. Moreover, the environmental influences introduced by vibrations, shock, acceleration, and so on, on the thermal performance and reliability of the TMS are specially emphasized and discussed in detail, which are usually neglected in normal operating conditions. Eventually, the possible future directions are discussed, aiming to serve as a reference guide for engineers and promote the advancement of the next-generation electronics TMS in automobile and aircraft applications.
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