RESUMO
Transition-metal-catalyzed lactamization and lactonization of C-H bonds with CO2 assisted by the chelation of amino or hydroxyl groups have been developed but limited to the use of precious metal catalysts such as palladium and rhodium. In this work, we report the nonprecious metal nickel-catalyzed lactamization reaction of 2-arylanilines with CO2 under redox-neutral conditions via C-H bond activation. The reaction displayed excellent functional group tolerance, providing various phenanthridinones with moderate to high yields.
RESUMO
Laser ranging based on a single-photon avalanche diode (SPAD), offering single-photon level high sensitivity, has been widely adopted in light detection and ranging (lidar) systems for long-distance ranging and imaging applications. Count detection through multiple pulses is commonly used when considering the existence of dark counting and strong background counting during the daytime, which improves the signal-to-noise ratio but at the expense of low detection speed. Here, we report a novel coded-pulse-bunch-laser-based single-photon lidar system, which aims to improve the ranging speed greatly and to expand the unambiguous distance to several kilometers. The schematic principle and construction of the lidar system, as well as the encoding method, are introduced. The time-of-flight (TOF) ranging information is extracted through real-time correlation between the transmitted pulse-bunch patterns and the received echo signals in a field-programmable gate array (FPGA). A daytime ranging experiment is demonstrated on a non-cooperative mountain target that is 5.4 km away. The method will be of great potential in fast three-dimension (3D) single-photon lidar imaging application for its relatively high data refreshing rate and large unambiguous distance.