Copper salts, which are abundant, relatively inexpensive and possess low toxicity, have long been used as versatile catalysts for various reactions in organic synthesis. Recently, the development of Cu‐catalyzed or ‐mediated CH functionalization reactions has gained significant attention. Since the pioneering work of Daugulis on the introduction of 8‐aminoquinoline and picolinic acid auxiliaries as removable directing groups in transition metal‐catalyzed CH bond activations, the combination of copper salts with these bidentate directing groups has emerged as an innovative strategy for the construction of carbon‐carbon or carbon‐heteroatom bonds through CH bond cleavage. In addition to the 8‐aminoquinoline and picolinamide systems, several other bidentate directing groups including the 2‐aminophenyloxazoline group by Yu and Dai and the PIP system by Shi, have been developed as well. This review intends to cover most of the recent advances on copper‐catalyzed or ‐mediated direct sp2 and sp3 CH bond functionalizations assisted by these bidentate directing groups. The major achievements in this area are discussed and catalogued by the type of bonds formed (CC, CO, CN, CS, CP etc.). Special attention is paid to the reaction mechanisms. Selected examples of substrates are listed as well. In addition, a personal outlook is given at the end.
Asteroids and other extraterrestrial impactor threats to Earth occur naturally in our solar system. Larger, more massive bodies including cometary fragments in high energy trajectories will be able to pierce the Earth's atmosphere and cause cataclysmic destruction if they are not stopped well enough in advance. Modern Directed Energy Systems are an emerging feasible concept for mitigating the threat of Near-Earth Objects (NEOs). Directed Energy Systems are versatile, scalable, reusable architectures that focus intense coherent beams of energy on a target's surface through the use of phased array lasers. The energy is typically used for the purpose of ablating the surface of the target, or generating substantial ablative thrust to alter the trajectory of the bolide to a new innocuous path. Technologies are fast maturing that allow the integration, test and commissioning of such directed energy systems for use at astronomical distances. This concept architecture study explored innovative strategies for directed energy system application to potentially hazardous asteroid threat.
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