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Ono K Yoshida A Saito N Fujishima T Honzawa S Suhara Y Kishimoto S Sugiura T Waku K Takayama H Kittaka A 《The Journal of organic chemistry》2003,68(19):7407-7415
Six novel 2-substituted analogues of 1alpha,25-dihydroxy-19-norvitamin D(3), 6a,b-8a,b, were efficiently synthesized utilizing (-)-quinic acid as the A-ring precursor. The C2-modified A-rings were prepared as 4-alkylated (3R,5R)-3,5-dihydroxycyclohexanones 12-15 from (-)-quinic acid based on radical allylation at the C4 position of methyl (-)-quinicate. The new type of the CD-ring coupling partner 23 was synthesized from 25-hydroxy Grundmann's ketone 19 to apply to the modified Julia olefination to construct a diene unit between the A-ring and the CD-ring. The coupling yields, including a deprotection step, were 47-62%. After the separation of the diastereomers based on C2 stereochemistry, the structure (2alpha or 2beta) was determined by (1)H NMR experiments and compared to DeLuca's 2-methyl- and 2-ethyl-1alpha,25-dihydroxy-19-norvitamin D(3). Thus, the synthesized 2alpha-(3-hydroxypropyl)-1alpha,25-dihydroxy-19-norvitamin D(3) (8a) showed almost the same potency in binding to the bovine thymus vitamin D receptor (VDR) as the natural hormone 1, while its beta-isomer 8b had only a 3% affinity. Both 2alpha-allyl- and 2alpha-propyl-1alpha,25-dihydroxy-19-norvitamin D(3) (6a and 7a) and their 2beta-analogues (6b and 7b) possessed a weak affinity for the VDR. The strong VDR ligand 8a was ca. 36-fold more potent in induction of HL-60 cell differentiation than 1, and interestingly, even the weaker ligand 8b showed a 6.7-fold higher potency in the cell differentiation activity than that of 1. 相似文献
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A novel synthetic basic resolving agent, cis-1-aminobenz[f]indan-2-ol (ABI), was rationally designed by introducing effective CH/pi interaction sites to cis-1-aminoindan-2-ol (AI), whose chiral recognition ability has been reported from our laboratory. ABI was applicable to a wide variety of racemic arylalkanoic acids and showed moderate to excellent chiral recognition ability, which was obviously higher than that of AI. The fundamental and important role of CH/pi interactions, such as tunable CH(sp(2))/pi and CH(sp(3))/pi interactions, in the chiral recognition by ABI was revealed by X-ray crystallographic study. 相似文献
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Two novel stereoisomeric analogues of 1,25-dihydroxyvitamin D3 bearing a spiro-oxetane at the C3 position of the A-ring have been designed and synthesized in a convergent manner. The absolute configuration at the C1 position of the synthesized compounds was determined by the circular dichroism exciton chirality method using the corresponding C1-allylic benzoates. The replacement of the C3-hydroxy group with a spiro-oxetane provided an advantageous conformational preference for the parent seco-steroids, which would facilitate the formation of a stable receptor complex. 相似文献
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Toshie Tahara Yoshitsugu Sakuda Mitsuaki Kodama Yoshimasa Fukazawa Shô Itô Kazuyoshi Kawazu Shuhei Nakajima 《Tetrahedron letters》1980,21(19):1861-1862
The structures of xantholides A and B were deduced on the basis of IR and NMR spectra, and confirmed by X-ray analysis. Xantholide A inhibited the larval growth of Drosophila melanogaster. 相似文献
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The 7-endo Friedel-Crafts cyclization of arylpropyl vinyloxiranes was found to proceed regio- and stereoselectively to afford polyfunctional seven-membered carbocycles in excellent yields. 相似文献
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N-Alkyl-N(1-hydroperoxyalkyl)nitrosamines were synthesized from N,N-dialkylnitrosamines by lithiation with lithium diisopropylamide, followed by oxygenation with oxygen in good yields. 相似文献
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Ryosuke Sugiyama Takahiro Nakatani Shinichi Nishimura Kei Takenaka Taro Ozaki Shumpei Asamizu Hiroyasu Onaka Hideaki Kakeya 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13620-13625
Organisms often produce secondary metabolites as a mixture of biosynthetically related congeners. However, why are metabolites with minor chemical variations produced simultaneously? 5‐Alkyl‐1,2,3,4‐tetrahydroquinolines (5aTHQs) are small, lipophilic metabolites produced by Streptomyces nigrescens HEK616 when cultured with Tsukamurella pulmonis TP‐B0596. A mixture of 5aTHQs forms aggregates that show enhanced membrane affinity and biological activity. The ability to form aggregates and membrane‐binding activity is regulated by the length of the alkyl chains. Aggregates with long alkyl chains were too stable to fuse with lipid membranes. However, if inactive 5aTHQ congener was mixed with active congener, the mixture showed increased membrane affinity, enabling cellular entry and biological activity. Therefore, it is shown that sloppiness in a biosynthetic pathway, by which minor structural variations can be produced, is functionally rational, as the metabolites show synergistic action. 相似文献
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Nobuyuki Tomioka Daisuke Takasu Toshie Takahashi Takuzo Aida 《Angewandte Chemie (International ed. in English)》1998,37(11):1531-1534
Carboxylate and ammonium functionalities—32 of each— facilitate electrostatic interaction between oppositely charged dendrimer electrolytes and porphyrin cores, which leads in protic media to a supramolecular, fluorescence-active aggregate of two chromophores that communicate and have a predictable topology (see drawing on the right; A=acceptor, D=donor). In contrast to the complexation of linear polyelectrolytes, the contact area for the two dendrimer molecules is very limited, just as one would expect for an assembly of spherical molecules. 相似文献