We have developed an efficient oxidative α-hydroxylation of β-keto esters with firstly using the structurally simple ethylenediamine-copper(ii) as a catalyst for β-keto esters activation and using visible light as the driving force for generating more active singlet oxygen (1O2) from triplet state oxygen (3O2) in the air, providing a series of α-hydroxy β-keto esters in excellent yields (up to 99%) under extremely low photosensitizer loading (0.01 mol%) and catalyst loading (1 mol%) within a short time. Moreover, the gram-scale synthesis showed the practical utility of this protocol.
Pachydermoperiostosis (PDP), or primary hypertrophic osteoarthropathy (PHO), is a rare hereditary disease mainly affecting skin and bones. The common clinical manifestations include digital clubbing, periostosis, and pachydermia. Patients often visit physicians because of thickened skin. However, the major concern of our patient was severe oedema of lower limb, although thickened facial skin also presented. Ascending phlebography revealed insufficient valve function of deep vein in lower limb. A reconstructive surgery was performed by enhancing the valve with tendon and by ligation of the great saphenous vein. Based on previous literatures, we hypothesize that the mechanism underlying the abnormalities in the valve of deep vein may be similar to that in skin and bones. We first report a PDP patient with a valve insufficiency treated with reconstructive surgery and we suggest that phlebography should be performed when the PDP patients present with severe pitting oedema in lower limbs.
A microemulsion electrokinetic capillary (MEEKC) chromatography method was online-coupled with field-amplified sample injection (FASI) for the analysis of nucleosides and nucleobases.
Abstract Electrical automation control system is a widely used system. With the development of computer technology, electrical automation control system and computer technology are combined to effectively improve the intelligence of electrical automation control. Electrical automation is also a very advanced technology.
A novel substrate-regulated [4+1] annulation of α-imidoyl sulfoxonium ylides with diazoketones under catalyst-free conditions is described. The reaction proceeds through a coupling of sulfoxonium ylides and in situ-generated ketenes to form the key reactive zwitterionic intermediates, followed by selective formation of C-C or C-O bonds to achieve five-membered ring systems. The cascade reaction permits the direct synthesis of synthetically useful 2-indanones and 3(2
Autonomous navigation in highly populated areas remains a challenging task for robots because of the difficulty in guaranteeing safe interactions with pedestrians in unstructured situations. In this work, we present a crowd navigation control framework that delivers continuous obstacle avoidance and post-contact control evaluated on an autonomous personal mobility vehicle. We propose evaluation metrics for accounting efficiency, controller response and crowd interactions in natural crowds. We report the results of over 110 trials in different crowd types: sparse, flows, and mixed traffic, with low- (< 0.15 ppsm), mid- (< 0.65 ppsm), and high- (< 1 ppsm) pedestrian densities. We present comparative results between two low-level obstacle avoidance methods and a baseline of shared control. Results show a 10% drop in relative time to goal on the highest density tests, and no other efficiency metric decrease. Moreover, autonomous navigation showed to be comparable to shared-control navigation with a lower relative jerk and significantly higher fluency in commands indicating high compatibility with the crowd. We conclude that the reactive controller fulfils a necessary task of fast and continuous adaptation to crowd navigation, and it should be coupled with high-level planners for environmental and situational awareness.
Catalytic asymmetric dearomatization (CADA) is a powerful tool for the rapid construction of complex chiral three-dimensional cyclic molecules featuring quaternary carbon centers from readily available arenes. However, the asymmetric dearomatization of ubiquitous nonfunctionalized 1-naphthols to afford chiral quaternary centers remains challenging and undeveloped. This study reports the asymmetric dearomative [4 + 1] spiroannulation of nonfunctionalized 1-naphthols via copper catalysis. This reaction features a highly chemo-, regio-, and stereoselective nucleophilic addition and intramolecular annulation cascade of a reactive π-extended copper-allenylidene, thus enabling the practical synthesis of a range of valuable spirocyclic enones bearing a chiral quaternary stereocenter with high efficiency. Furthermore, this protocol is applicable to phenols. Control experiments supported the substitution-annulation cascade mechanism by excluding a process involving a 1,3-sigmatropic shift. Preliminary biological activity studies indicated that the synthesized spirocyclic enones hold significant promise as anticancer agents by inducing tumor cell apoptosis.
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