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141.
142.
A convergent synthesis of the imidazopyridine scaffold of fluorescent alkaloid ageladine A (1) has been achieved, employing 3-amino-2-chloropyridine as the staring material. A carboxylic acid was introduced using n-butyllithium and dry ice as the key reaction. 相似文献
143.
El-Aasr M Fujiwara Y Takeya M Ono M Nakano D Okawa M Kinjo J Ikeda T Miyashita H Yoshimitsu H Nohara T 《Chemical & pharmaceutical bulletin》2011,59(11):1340-1343
Garlicnin A (1), a new stable, sulfur-containing compound isolated from a fraction of the acetone extracts of Allium sativum L. garlic bulbs, showed the potential to suppress tumor cell proliferation by inhibiting the polarization of M2 alternatively activated macrophages, and its structure was characterized as 3,4-dimethyl-5-(4,5-dithia-1E,7-octadiene)-tetrahydrothiophene-2-sulfoxide-S-oxide, on the basis of the results of spectroscopic analysis results. 相似文献
144.
Ono M Eguchi K Konoshita M Furusawa C Sakamoto J Yasuda S Ikeda T Okawa M Kinjo J Yoshimitsu H Nohara T 《Chemical & pharmaceutical bulletin》2011,59(3):392-396
A new labdane-type diterpenoid glucoside and two new labdane-type diterpenoids were isolated from the fruit (chasteberry) of Vitex agnus-castus L. (Verbenaceae) along with 14 known compounds comprising seven labdane-type diterpenoids, one halimane-type diterpenoid, two oleanane-type triterpenoids, two ursane-type triterpenoids, one aromadendrane-type sesquiterpenoid, and one flavonoid. Their structures were characterized on the basis of spectroscopic data as well as chemical evidence. Furthermore, the antioxidative activities of the flavonoid were evaluated using five different analyses. 相似文献
145.
Kosei Shioji Yoshimitsu Kurauchi Keiko Terada Yasushi Kodera Kentaro Okuma 《合成通讯》2013,43(13):2163-2170
Colyophilization of lipase was carried out with immobilized β‐cyclodextrins (β‐CyD) bearing methyl, acetyl, benzoyl, and nicotinoyl substituents. The colyophilizates enhanced stereoselectivity in the acylation of several alcohols. The enantioselectivity in the acylation of ethyl‐1‐hydroxymethyl‐phenylphosphine oxide using colyophilized lipase with nicotinoyl‐β‐CyD increased approximately threefold (from E=34 to E=113). The amphiphilic character of modified CyDs has been found to influence the enhancement of enantioselectivity. 相似文献
146.
Takehiko Yoshimitsu 《Chemical record (New York, N.Y.)》2014,14(2):268-279
Free radicals, which in the past were considered unruly chemical species, have become manageable and indispensable for synthetic organic chemistry. The unique nature of free radicals has allowed practitioners in organic synthesis to design flexible approaches to produce various materials ranging from small molecules to polymers. The present Personal Account describes the author's endeavors to create molecular complexity by the strategic use of free radicals, with an emphasis on the synthesis of bioactive natural products. 相似文献
147.
Enantiospecific Synthesis and Cytotoxicity Evaluation of Ligudentatol: A Programmed Aromatization Approach to the 2,3,4‐Trisubstituted Phenolic Motif via Visible‐Light‐Mediated Group Transfer Radical Cyclization 下载免费PDF全文
Gamal A. I. Moustafa Hiroshi Suizu Prof. Dr. Hiroshi Aoyama Prof. Dr. Masayoshi Arai Prof. Dr. Shuji Akai Prof. Dr. Takehiko Yoshimitsu 《化学:亚洲杂志》2014,9(6):1506-1510
A facile enantiospecific approach to (+)‐ligudentatol ( 1 ) and (?)‐ligudentatol (ent‐ 1 ) is reported. The approach features the construction of a trisubstituted phenolic motif fused to a chiral aliphatic ring by a sequence of visible‐light‐mediated radical seleno transfer cyclization, bromination, concomitant selenoxide elimination–dehydrobromination, and demethoxycarbonylation, namely, a programmed aromatization. Biological evaluation of the enantiomers of ligudentatol obtained by the present route revealed for the first time their cytotoxicity towards various cancer cell lines. 相似文献
148.
Kunio Kimura Shin‐ichiro Kohama Satomi Kondoh Tetsuya Uchida Yuhiko Yamashita Takeshi Oohazama Yoshimitsu Sakaguchi 《Journal of polymer science. Part A, Polymer chemistry》2005,43(8):1624-1634
Polymerization of 4‐acetoxybenzoic acid (ABA) with 3,5‐diacetoxybenzoic acid (DABA) was examined to control the morphology of poly(p‐oxybenzoyl) (POB). Polymerizations were carried out at a concentration of 1.0% in an aromatic solvent Therm S‐1000® (mixture of dibenzyltoluene) at 320 °C. Polymerization of ABA yielded the POB fibrillar crystals, but the polymerization with DABA at a concentration in the feed (χf) of 0.10–0.15 afforded novel network structures comprised of spheres connected by fibrillar crystals. The diameter of the spheres prepared at χf of 0.15, which were 0.7 and 5.0 μm, showed bimodality. The network distance, fibril length, and fibril width were 6.1, 2.6, and 0.1 μm, respectively. They possessed high crystallinity. The network structure was formed as follows. Co‐oligomers were first precipitated in the beginning of the polymerization by liquid–liquid phase separation to form the microdroplets. The fibrillar crystals were formed in the coalesced spheres by the crystallization of oligomers induced by the increase of molecular weight. The fibrillar crystals connecting the spheres gradually appeared owing to the shrinkage of the spheres. The fibrillar crystals grew from the surface of the spheres with the crystallization of homo‐oligomers of 4‐oxybenzoyl units, and finally the network structure was completed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1624–1634, 2005 相似文献
149.
Yoshimitsu Moritani Takeo Fukunaga Hiroyuki Ishida Setsuo Kashino 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(11):1349-1351
The low-temperature structure determination of the title compound, alternatively called ammonium hydrogen hydroxypropanedioate, NH4+·C3H3O5−, has revealed that the H atom involved in a very short asymmetric O—H⋯O hydrogen bond [O⋯O = 2.448 (2) Å at 240 K and 2.4393 (10) Å at 20 K] is disordered. 相似文献
150.
Masahito Ochiai Minako Inenaga Yoshimitsu Nagao
Robert M. Moriarty
Radhe K Vaid Michael P. Duncan 《Tetrahedron letters》1988,29(52):6917-6920Cyclic amino acids L-proline, pipecolinic acid and L-2-pyrrolidinone-5-carboxylic acid undergo oxidative decarboxylation with iodosobenzene in various solvents (including water) to yield the lactam and imide in the latter case. The reaction proceeds via initial imine formation. 相似文献