RESUMEN
For transition-metal-catalyzed C-H functionalization, precise differentiation between remote adjacent C(sp2)-H bonds remains a long-standing challenge. Here, the template structure-directivity relationship on remote C-H functionalization of arenes was experimentally and computationally studied. By using geometry-tunable templates, Pd-catalyzed remote meta- and para-C-H activation of benzoic acids was achieved with high site selectivity.
RESUMEN
The synthesis of macrocyclic compounds with different sizes and linkages remains a great challenge via transition metal-catalysed intramolecular C-H activation. Herein, we disclose an efficient macrocyclization strategy via Pd-catalysed remote meta-C-H olefination using a practical indolyl template. This approach was successfully employed to access macrolides and coumarins. In addition, the intermolecular meta-C-H olefination also worked well and was exemplified by the synthesis of antitumor drug belinostat from inexpensive and readily available benzenesulfonyl chloride. Notably, catalytic copper acetate and molecular oxygen were used in place of silver salts as oxidants. Furthermore, for the first time, the formation of a macrocyclophane cyclopalladated intermediate was detected through in situ Fourier-transform infrared monitoring experiments and ESI-MS.
RESUMEN
OBJECTIVE: To investigate the imaging and clinical feature of leukoencephalopathy with hearing loss first complaint. METHOD: The head MRI and clinical feature of 7 cases leukoencephalopathy with hearing loss first complaint were retrospectively analysed, including their place, shape, range and blood plasma very-long-chain fatty acid (VLCFA). RESULT: The head MRI of 2 cases shows symmetry distributed long T, and T2 signal like butterfly aliform in white matter beside both cornu posterior ventriculi lateralis. The head MRI of 5 cases shows abnormal long T1 and T2 signal in different part in Alba. The pathological changes often located in white matter of frontal lobe and secondly beside both cornu posterior ventriculi lateralis. The shape shows little patching in 7 cases. The range only shows beside cornu posterior ventriculi lateralis in 2 cases. The range only shows in frontal lobe in 1 cases. Two or more than two parts shows in the rest 5 cases. The result of VLCFA is normal in 3 cases. The rest 4 cases refused to have examination of VLCFA. CONCLUSION: The patient who firstly complained of hearing loss should be routinely done head MRI. The head MRI imaging could clearly show abnormal white matter in order to avoid omitting existent pathological changes.
