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91.
A syn‐Selective Aza‐Aldol Reaction of Boron Aza‐Enolates Generated from N‐Sulfonyl‐1,2,3‐Triazoles and 9‐BBN‐H 下载免费PDF全文
Dr. Tomoya Miura Takayuki Nakamuro Sho Miyakawa Prof. Dr. Masahiro Murakami 《Angewandte Chemie (International ed. in English)》2016,55(30):8732-8735
A syn‐selective aza‐aldol reaction of boron aza‐enolates, generated from N‐sulfonyl‐1,2,3‐triazoles and 9‐BBN‐H, is reported. It provides a sequential one‐pot procedure for the stereoselective construction of 1,3‐amino alcohols, having contiguous stereocenters, starting from terminal alkynes. 相似文献
92.
Cascade Synthesis of Five‐Membered Lactones using Biomass‐Derived Sugars as Carbon Nucleophiles 下载免费PDF全文
Dr. Sho Yamaguchi Takeaki Matsuo Dr. Ken Motokura Dr. Akimitsu Miyaji Prof. Toshihide Baba 《化学:亚洲杂志》2016,11(11):1731-1737
We report the cascade synthesis of five‐membered lactones from a biomass‐derived triose sugar, 1,3‐dihydroxyacetone, and various aldehydes. This achievement provides a new synthetic strategy to generate a wide range of valuable compounds from a single biomass‐derived sugar. Among several examined Lewis acid catalysts, homogeneous tin chloride catalysts exhibited the best performance to form carbon–carbon bonds. The scope and limitations of the synthesis of five‐membered lactones using aldehyde compounds are investigated. The cascade reaction led to high product selectivity as well as diastereoselectivity, and the mechanism leading to the diastereoselectivity was discussed based on isomerization experiments and density functional theory (DFT) calculations. The present results are expected to support new approaches for the efficient utilization of biomass‐derived sugars. 相似文献
93.
Takahiro Ikazaki Dr. Eri Ishikawa Hiroto Tamashima Dr. Hisako Akiyama Dr. Yusuke Kimuro Dr. Makoto Yoritate Dr. Hiroaki Matoba Prof. Dr. Akihiro Imamura Prof. Dr. Hideharu Ishida Prof. Dr. Sho Yamasaki Prof. Dr. Go Hirai 《Angewandte Chemie (International ed. in English)》2023,62(22):e202302569
Glycoconjugate analogues in which the sp3-hybridized C2 position of the carbohydrate structure (normally bearing a hydroxy group) is converted into a compact sp2-hybridized exomethylene group are expected to have unique biological activities. We established ligand-controlled Tsuji–Trost-type glycosylation methodology to directly prepare a variety of these 2-exomethylene pseudo-glycoconjugates, including glucosylceramide analogues, in an α- or β-selective manner. Glucocerebrosidase GBA1 cleaves these synthetic pseudo-β-glucosylceramides similarly to native glucosylceramides. The pseudo-glucosylceramides exhibit selective ligand activity towards macrophage-inducible C-type lectin (Mincle), but unlike native glucosylceramides, are inactive towards CD1d. 相似文献
94.
Matsuda T Kadowaki S Yamaguchi Y Murakami M 《Chemical communications (Cambridge, England)》2008,(24):2744-2746
3-Allyl-1-silaindenes are synthesised from alkynes having an allylsilane moiety by a gold-catalysed intramolecular trans-allylsilylation reaction. 相似文献
95.
This paper describes a synthetic approach to a novel D-glucose-conjugated 15-crown-5 ether having a spiroketal structure starting from a 1-C-vinylated glucose derivative. The approach consists of the glycosylation of the vinylated glucose derivative to give an ethyleneoxy spacer derivative using bismuth(III) triflate, the conversion of the 1-C-vinyl group of the glucoside produced into a carboxylic acid group, and the intramolecular condensation between the carboxyl group and the terminal hydroxyl group in the ethyleneoxy spacer. A D-glucose-conjugated 15-crown-5 ether having a unique spiroketal structure was thus successfully synthesized. 相似文献
96.
Furuyama T Yonehara M Arimoto S Kobayashi M Matsumoto Y Uchiyama M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(33):10348-10356
We present full details of the unique reactivities of the newly developed dianion-type bulky zincate, dilithium tetra-tert-butylzincate (tBu(4)ZnLi(2)). With this reagent, halogen-zinc exchange reaction of variously functionalized haloaromatics and anionic polymerization of N-isopropylacrylamide (NIPAm)/styrene with excellent chemoselectivity were realized. Halogen-zinc exchange reaction followed by electrophilic trapping with propargyl bromide provided a convenient route to functionalized phenylallenes, particularly those with electrophilic functional groups (such as cyano, amide and halogens). Spectral and computational studies of the structure in the gas and liquid phases indicated extraordinary stabilization of this dianion-type zincate by its bulky ligands. 相似文献
97.
Shu Fujita Dr. Sho Yamaguchi Dr. Jun Yamasaki Dr. Kiyotaka Nakajima Prof. Seiji Yamazoe Prof. Tomoo Mizugaki Dr. Takato Mitsudome 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(13):4439-4446
Non-noble metal-based hydrogenation catalysts have limited practical applications because they exhibit low activity, require harsh reaction conditions, and are unstable in air. To overcome these limitations, herein we propose the alloying of non-noble metal nanoparticles with phosphorus as a promising strategy for developing smart catalysts that exhibit both excellent activity and air stability. We synthesized a novel nickel phosphide nanoalloy (nano-Ni2P) with coordinatively unsaturated Ni active sites. Unlike conventional air-unstable non-noble metal catalysts, nano-Ni2P retained its metallic nature in air, and exhibited a high activity for the hydrogenation of various substrates with polar functional groups, such as aldehydes, ketones, nitriles, and nitroarenes to the desired products in excellent yields in water. Furthermore, the used nano-Ni2P catalyst was easy to handle in air and could be reused without pretreatment, providing a simple and clean catalyst system for general hydrogenation reactions. 相似文献
98.
Mathematical Programming - We present a semidefinite programming approach to bound the measures of cross-independent pairs in a bipartite graph. This can be viewed as a far-reaching extension of... 相似文献
99.
100.
Sho HiraiMasahisa Nakada 《Tetrahedron》2011,67(2):518-530
Enantioselective divergent approaches to (−)-platencin and (−)-platensimycin have been developed. A rationally designed chiral synthetic intermediate, possessing a useful α,β-unsaturated sulfone functionality, which served as a masked ketone as well as a good Michael acceptor, was successfully prepared via the highly enantioselective catalytic asymmetric intramolecular cyclopropanation (CAIMCP) developed in our laboratory. 相似文献