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271.
Akiyama K Hamano T Nakanishi Y Takeuchi E Noda S Wang Z Kubuki S Shinohara H 《Journal of the American Chemical Society》2012,134(23):9762-9767
Rapid and efficient separation/purification of pure metallofullerenes M(x)@C(n) (M = metal; x = 1, 2; n > 70) and carbide metallofullerenes of the type M(y)C(2)@C(n-2) (y = 2, 3, 4; n - 2 > 68) has been reported. The present method utilizes rapid and almost perfect preferential formation of TiCl(4) (generally known as a Lewis acid)-metallofullerene complexes, which easily decompose to provide pure metallofullerene powders by a simple water treatment. The present method enables one to separate the metallofullerenes up to >99% purity within 10 min without using any type of high-performance liquid chromatography (HPLC). It is found that the oxidation potentials of the metallofullerenes are crucial factors for efficient purification. The current separation/purification technique may open a brand-new era for inducing further applications and commercialization of endohedral metallofullerenes. 相似文献
272.
Ohkita H Cook S Astuti Y Duffy W Heeney M Tierney S McCulloch I Bradley DD Durrant JR 《Chemical communications (Cambridge, England)》2006,(37):3939-3941
Efficient triplet formation is observed for films of high ionisation potential polythiophenes blended with a fullerene derivative, and assigned to formation via geminate charge recombination of bound radical ion pair states. 相似文献
273.
Ellis TK Ueki H Yamada T Ohfune Y Soloshonok VA 《The Journal of organic chemistry》2006,71(22):8572-8578
A new generation of modular achiral glycine equivalents have been evaluated with respect to their synthetic utility for the production of tailor-made, sterically constrained alpha-amino acids, which proved to be the most efficient approach developed to date for the synthesis of symmetrical alpha,alpha-disubstituted-alpha-amino acids. Among the new series of achiral glycine equivalents, one was found to be a superior glycine derivative for the Michael additions with various (R)- or (S)-N-(E-enoyl)-4-phenyl-1,3-oxazolidin-2-ones representing a general and practical synthesis of sterically constrained beta-substituted pyroglutamic acids. In particular, the application of these complexes allowed for the preparation of several beta-substituted pyroglutamic acids which include electron-releasing and sterically demanding substituents in the structure thus increasing the synthetic efficiency and expanding the generality of these Michael addition reactions. 相似文献
274.
This paper presents a highly stereoselective synthesis of trifluoro- or difluoromethylated olefins via an S(N)2' type fluorination or reductions of gem-difluorinated vinyloxiranes. Their fluorination with HF-Py furnished trifluoromethylated allylic alcohols with exclusive E selectivity. On the other hand, their reduction with DIBAL-H afforded difluoromethylated E-allylic alcohols predominantly, whereas the corresponding Z isomers were formed exclusively by treatment with BH3.THF. 相似文献
275.
276.
Hidetoshi Kawai Takanori Suzuki Masakazu Ohkita Takashi Tsuji 《Angewandte Chemie (International ed. in English)》1998,37(6):817-819
Benzene rings severely bent and closely stacked face-to-face are revealed in the crystal structure of the [1.1]paracyclophane derivative 1 , which could be isolated thanks to the kinetic stabilization provided by the steric shielding of the bridgehead sites by the substituents. 相似文献
277.