共查询到20条相似文献,搜索用时 312 毫秒
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以3-氨基-1-[3-(环己基甲氧基)苯基]丙-1-醇为原料,经氨基保护、氧化、手性还原、脱保护和成盐等5步反应合成了Emixustat,总收率30.7%,其结构经1H NMR和MS(ESI)确证。 相似文献
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[Structure: see text] Subunits of phorboxazole A containing C1-C2, C3-C8, C9-C19, C20-C32, C33-C41, and C42-C46 were connected in a sequence that first linked C32 with C33 and then C41 with C42. A C3-C8 fragment was joined to C9-C19, and the assembled unit was then joined with the left half of 1. Closure of the macrolide was accomplished by esterification of the C24 alcohol followed by intramolecular Horner-Wadsworth-Emmons condensation to set the (E)-C2-C3 alkene. 相似文献
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Journal of Thermal Analysis and Calorimetry - The hydration of C3A, C3S and C3A+C3S mixtures was examined by thermogravimetry, differential thermogravimetry and calorimetry. The results showed the... 相似文献
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利用溶胶-凝胶法制备了C12A7-O-{[Ca24Al28O64]4+·4(O-)}纳米材料. 采用X射线衍射、电子顺磁共振及透射电子显微镜等手段对制备的材料进行了表征. 结果表明, 在最佳焙烧条件(1150 ℃, 6 h)下制备的材料平均粒径为74 nm, 并具有晶胞参数为(1.199±0.004) nm的C12A7(Ca12Al14O33)笼状结构, 材料内包含浓度高达1.2×1020 cm-3的氧负离子(O-). 初步研究结果表明, 合成的C12A7-O-纳米材料具有良好的广谱抗菌作用. 相似文献
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A highly convergent formal synthesis of the auriside aglycon was achieved. An indene-based thiazolidinethione chiral auxiliary was used for the construction of both the C1-C9 and C10-C17 fragments via acetate aldol reactions. A Meinwald reaction was utilized to install the stereocenter at C2, and a conjugated addition to an ynone was used to construct the C9-C11 enone. 相似文献
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Tomonori Mori Dr. Shuhei Higashibayashi Dr. Taiji Goto Mitsunori Kohno Yukiko Satouchi Kazuyuki Shinko Kengo Suzuki Shunya Suzuki Hiraku Tohmiya Kimiko Hashimoto Prof. Dr. Masaya Nakata Prof. Dr. 《化学:亚洲杂志》2008,3(6):1013-1025
The total synthesis of siomycin A ( 1 ), a representative compound of the thiostrepton family of peptide antibiotics, was achieved by incorporating the five synthetic segments A ( 2 ), B ( 3 ), C ( 4 ), D ( 5 ), and E ( 6 ). The dehydropiperidine segment A ( 2 ) was esterified with the dihydroquinoline segment C ( 4 ), and the subsequent coupling with the β‐phenylselenoalanine dipeptide segment D ( 5 ) at the segment C portion followed by lactamization between the segments A and D gave segment A‐C‐D ( 27 ). This was amidated with the pentapeptide segment B ( 3 ) at the segment A portion followed by one‐pot cyclization (between segments A and B) and elongation (with the β‐phenylselenoalanine dipeptide segment E ( 6 ) at the segment A portion), thus furnishing siomycin A ( 1 ). 相似文献
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Tushar Kanti Chakraborty Bajjuri Krishna Mohan Midde Sreekanth 《Tetrahedron letters》2006,47(29):5003-5005
A stereoselective synthesis of the C22-C34 fragment of the non-immunosuppressive immunophilin-binding natural product, antascomicin A was achieved using d-quinic acid as the starting material and highly stereoselective aldol reactions were employed, as key steps, to build the remaining stereocentres at C23, C26 and C27. 相似文献
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The complex marine alkaloid norzoanthamine (2) was envisioned to be assembled from three key building blocks: the C1-C5 fragment A, the C6-C10 fragment B, and the C11-C24 fragment C. The synthesis of fragment A was achieved in 14 steps and 33% overall yield from (R)-gamma-hydroxymethyl-gamma-butyrolactone. Fragment B was made in two steps from PMB-protected 4-pentynol in 76% yield. The C11-C24 fragment C was made from (S)-carvone via (R)-isocarvone in 18 steps (6% overall yield). The convergent stereoselective synthesis of the entire carbon framework (C1-C24) of the target molecule was achieved via the following assemblage. Alkenyl iodide 20 derived from the C11-C24 fragment C was coupled to fragment B (C6-C10) through a high-yielding Stille coupling reaction of these two sterically very demanding coupling partners, affording the key Diels-Alder precursor 24. The intramolecular Diels-Alder reaction proceeded smoothly in excellent yield and diastereoselectivity, generating the tricyclic trans-anti-trans perhydrophenanthrene motif of norzoanthamine (C6-C24). The final fragment coupling between lithiated fragment A (C1-C5) and aldehyde 40 (C6-C24) has also been successfully accomplished affording the entire carbon framework of the natural product. 相似文献
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设计了与富含胞嘧啶(C)的DNA序列d(C4)相关的DNA序列d(C4), d(TC4), d(AC4), d(T2C4), d(A2C4), d(C4T), d(C4A)和d(TC4T); 采用电喷雾质谱测定发现这些序列形成四分子非共价复合物离子, 根据离子的相对丰度可确定形成四链i-motif结构的数量和可能性; 同时考察了腺嘌呤(A)和胸腺嘧啶(T)在d(C4)序列的5'和3'端对其形成四分子i-motif结构的影响. 结果表明, 在d(C4)的5'端增加A碱基或T碱基更易形成四分子复合物; 5'端含T碱基比含A碱基更利于形成四分子复合物; 而在d(C4)序列中增加2个A碱基或T碱基比增加相应的单个碱基形成了更高丰度的四分子离子峰. 相似文献
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Masashi Miyakawa Hidenori Hiramatsu Masahiro Hirano 《Journal of solid state chemistry》2010,183(2):385-391
Epitaxial growth and electron doping of 12CaO·7Al2O3 (C12A7) and 12SrO·7Al2O3 (S12A7) are reported. The C12A7 films were prepared on Y3Al5O12 (YAG) single-crystal substrates by pulsed laser deposition at room temperature and subsequent thermal crystallization. X-ray diffraction patterns revealed the films were grown epitaxially with the orientation relationship of (001)[100] C12A7 || (001)[100] YAG. For S12A7, pseudo-homoepitaxial growth was attained on the C12A7 epitaxial layer. Upon electron doping, metallic conduction was achieved in the C12A7 film and the S12A7/C12A7 double-layered films. Analyses of optical absorption spectra for the S12A7/C12A7 films provided the densities of free electrons in each layer separately. Hall measurements exhibited larger electron mobility in the S12A7/C12A7 film than those in C12A7 and S12A7 films, suggesting free electrons may be accumulated at the S12A7/C12A7 interface due presumably to a discontinuity of the cage conduction bands. 相似文献
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Lei Peng Fu-Min ZhangBing-Miao Yang Xiao-Bo ZhangWen-Xing Liu Shu-Yu ZhangYong-Qiang Tu 《Tetrahedron letters》2013
The total synthesis of isomer of didemnaketal A was achieved in 26 steps. The position of esters is switched at C7 and C8 with respect to their proposed position in natural didemnaketal A, which shows potent anti-HIV activity but so far has not been synthesized in the laboratory. Structural analysis of synthetic isomer of didemnaketal A indicates that the esters at C7 and C8 are correctly assigned, suggesting that the problems for the structural reassignment of natural didemnaketal A lie elsewhere. 相似文献