Search

The palladium-catalyzed alkoxycarbonylation of polybromo­(hetero)arenes was investigated systematically. The results show that cheap and readily available in situ Pd(OAc)2/rac-BINAP catalyst can catalyze the butoxycarbonylation of various polybromo(hetero)arenes efficiently, and gave (hetero)arenepolycarboxylates with moderate to high yield (59–94%). Using this method, two new compounds, 4,4′-bis(butoxycarbonyl)-1,1′-bi-2-naphthol and dibutyl [2,2′-bipyrimidine]-5,5′-dicarboxylate, are reported for the first time. In addition, the gram-scale preparation of carboxylate and carboxylic acids was successful performed by butoxycarbonylation followed by hydrolysis. This shows the wide scope of substrates and practical applications of the Pd(OAc)2/rac-BINAP catalytic system. Moreover, these carboxylic acids and carboxylates can be used as ligands or structural units to construct MOFs, metal complexes, and COFs etc.

In wireless laser communication, the effects of atmospheric turbulence cause laser spots to appear as irregular speckles in the far-field plane, which may make automatic acquisition, pointing, and tracking systems unable to locate a spot position. We propose an innovative and precise anti-interference, spot-detection algorithm for far-field irregular speckles based on the intensity characteristics of the far-field spots. Before obtaining the spot center coordinates through two-dimensional vector space circle fitting, the proposed algorithm employs computer graphics combined with mathematical morphology to fill the connected domains and extracts light-spot edges using the Canny operator, thus resulting in an accurate detection of far-field spots. The algorithm validation, using an automated experimental platform (atmospheric turbulent refractive-index structure parameter C n 2 is 10 − 15 m − 2/3), yields a detection threshold accuracy of 30 to 32 pixels (each pixel represents 3 μrad) for 10.2 km far-field spot images. The corresponding deviation satisfies the two-dimensional aiming platform for a minimum step distance of 17.45 μrad, verifying the feasibility and effectiveness of the algorithm.