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A Mg(ClO4)2-catalyzed intramolecular amination of allylic alcohols with carbamate or sulfonamide nucleophiles to form substituted piperidine and pyrrolidine derivatives has been developed. This method has been successfully applied to the total synthesis of demethoxyfumitremorgin C. 相似文献
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Experiment and simulation were used to study the flow fields of a liquid-solid-solid three-phase system in a draft-tube stirred reactor with a six-flat-bladed t... 相似文献
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A stereocontrolled total synthesis of (+)-lysergic acid (1) is achieved using three metal-catalyzed methodologies for the construction of three key rings. Highlights of the synthesis include Pd-catalyzed indole synthesis to form the B ring, a RCM reaction to form the D ring, and an intramolecular Heck reaction to form the C ring. 相似文献
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We present a new approach for simultaneous spectral and coherent combining in a master oscillator power amplifier (MOPA) configuration with active phasing. Spectrally combined single-frequency seed lasers are employed as a master oscillator for the all-fiber power amplifier chain, which provides robust performance suppressing of the stimulated Brillouin scattering effect, while coherent combining of spectrally combined amplifiers with active phase control provides stable in-phase combining, despite the strong phase fluctuation. In experiments, two spectrally combined seed MOPA chains are coherently combined with a total output power of 390 W. The power of the main lobe in the closed loop is two times of that value in the open loop, and visibility of more than 75% of the long-exposure interference pattern at the receiving plane is obtained. 相似文献
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The adsorption, diffusion and dissociation properties of O2 on the icosahedron (Ih) Ni@Pt12 core-shell nanoparticle were investigated using the ab initio density functional theory calculations. It is found that, compared with the Pt(111) surface, the Ih Ni@Pt12 core-shell nanoparticle can enhance the adsorption, diffusion and dissociation of O2, as well as the adsorption and diffusion of the atomic O (the dissociation product of O2), and therefore serve as a good catalyst for oxygen reduction reaction. Our study gives a reasonable theoretical explanation to the high catalytic activity of the Ni@Pt core-shell nanoparticles for the oxygen reduction reaction. 相似文献
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A formal synthesis of semiaquilegin A is achieved starting from readily available oridonin in 19 linear steps. The absolute configuration of the natural product has been established. A variety of useful analogues were prepared through this synthetic route. 相似文献
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