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211.
A cationic CpRu complex of chiral picolinic acid derivatives [(R)- or (S)-Cl-Naph-PyCOOCH(2)CH═CH(2)] catalyzes asymmetric intramolecular dehydrative N-allylation of N-substituted ω-amino- and -aminocarbonyl allylic alcohols with a substrate/catalyst ratio of up to 2000 to give α-alkenyl pyrrolidine-, piperidine-, and azepane-type N-heterocycles with an enantiomer ratio of up to >99:1. The wide range of applicable N-substitutions, including Boc, Cbz, Ac, Bz, acryloyl, crotonoyl, formyl, and Ts, significantly facilitates further manipulation toward natural product synthesis. 相似文献
212.
213.
Ikeda M Fukuda K Tanida T Yoshii T Hamachi I 《Chemical communications (Cambridge, England)》2012,48(21):2716-2718
A boronic acid-appended fluorescent receptor was incorporated into self-assembled nanofibers containing a hydrophobic FRET-paired dye to develop a gel-based fluorocolorimetric sensor for polyols. We demonstrated that the gel-based sensor is capable of detecting polyols such as catechol and dopamine not only under semi-wet conditions, but also under dry conditions using a paper platform. 相似文献
214.
Noguchi M Nakamura M Ohno A Tanaka T Kobayashi A Ishihara M Fujita M Tsuchida A Mizuno M Shoda S 《Chemical communications (Cambridge, England)》2012,48(45):5560-5562
An efficient chemo-enzymatic process for construction of the α-linked disaccharide unit (GlcNAcα1-4Gal) found in gastric mucin has been developed. The process consists of a one-step preparation of a novel triazine type glycosyl donor in water and the subsequent transglycosylation to a galactose derivative catalysed by α-N-acetylglucosaminidase. 相似文献
215.
Ide Y Torii M Tsunoji N Sadakane M Sano T 《Chemical communications (Cambridge, England)》2012,48(56):7073-7075
Hiroshima University Silicate-1 (HUS-1), composed of silicate sheets with a halved sodalite cage and the interlayer tetramethylammonium (TMA) cation in the cage, was modified with dimethyldichlorosilane to form the organic derivative in which a dimethyl group was grafted onto the interlayer surface and a part of the TMA was removed, and the silylated HUS-1 effectively and selectively adsorbed TMA from water even in the presence of aqueous phenol. 相似文献
216.
Phosphinylthiolation of terminal alkynes with Ph2P(O)SBu or a related compound proceeds in the presence of a palladium–PEt3 catalyst system. Activity and stereoselectivity are highly dependent on the nature of solvent, ethylbenzene, and n-hexanol (or t-amyl alcohol) being E- and Z-selective, respectively. 相似文献
217.
Masato Tsujii 《Communications in Mathematical Physics》2000,208(3):605-622
We prove the existence of absolutely continuous invariant measures for piecewise real-analytic expanding maps on bounded regions
in the plane.
Received: 5 June 1998 / Accepted: 11 May 1999 相似文献
218.
Type I (α-) and II cleavages are two of the best known photochemical processes of alkanone.2 Extensive and intensive investigations have been done on both types of reactions in order to clarify the influence of structural changes on the reactivity, specificity, and efficiency of photoreactions of alkanones.3 The type I cleavage of medium-ring alkanones is believed to produce a radical pair, the fate of which will be determined by the ready formation of transition states for transfer of Ha, Hb, and recyclization. We now wish to report 相似文献
219.
220.
Acyclic asymmetric induction was achieved in >99 % formation via coordinated intermediate () in the heteroconjugate addition ( to ); the heteroatom in the adduct being used for elongation of the carbon chain toward maytansine ). 相似文献