共查询到19条相似文献,搜索用时 203 毫秒
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以4-氨基-5-氯-2,3-二氢苯并呋喃-7-羧酸和1-(3-甲氧基丙基)-4-哌啶胺为原料,通过酰胺缩合反应合成了普卡必利.普卡必利化学名为4-氨基-5-氯-2,3-二氢-N-[1-(3-甲氧基丙基)-4-哌啶基]-7-苯并呋喃甲酰胺,是二氢苯并呋喃的衍生物5-H4受体拮抗剂,是一种治疗慢性便秘的重要药物.普卡必利结构中存在多个化学环境非常接近的碳原子,核磁共振(NMR)谱图相对复杂.本文首先应用超高效液相色谱-串联质谱(UPLC-MS/MS)和液相色谱-高分辨质谱(LC-HRMS)对其元素组成进行了分析,进而用一维和二维NMR谱(包括1H NMR、13C NMR、DEPT、1H-1HCOSY、1H-13C HSQC、1H-13C HMBC)对普卡必利的1H和13C NMR信号进行了指认归属,确定了其结构.本工作对苯并呋喃衍生物及相关下游药物合成工艺的进一步优化,以及相关衍生药物的研究具有参考价值. 相似文献
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中枢抗胆碱药物苯环壬酯-2′-苯基-2′-环戊基-2′-羟基乙酸-N-甲基-3-氮杂双环(3,3,1)壬-9α-酯的化学结构比较复杂,部分谱峰重叠,本文采用2种NMR新方法,MMDY混合脉冲梯度选择一维HOHAHA和多重激发梯度选择一维NOESY相结合对其1H NMR和立体化学进行了研究,重叠谱峰的归属得到确定. 根据NOE实验结果,证实该化合物为9α差向异构体,并且确定了在氘代氯仿中氮杂双环为椅式-椅式构象;哌啶环中氮甲基位于e键. 本结果有助于此类化合物的化学结构和溶液构象的测定. 相似文献
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1,2;5,6-双-O-异丙叉基-3-C-硝甲基-α-D-呋喃阿洛糖(化合物1)在酸性条件下选择性脱除5,6-异丙叉基得到C-3位构型保持的水解产物1,2-O-异丙叉基-3-C-硝甲基-α-D-呋喃阿洛糖(化合物2);化合物1先经过Moffatt脱水生成C-3硝基烯产物1,2;5,6-双-O-异丙叉基-3-脱氧-亚甲基硝基-α-D-呋喃木糖(化合物3),然后在酸性条件下选择性脱除5,6-异丙叉基过程中协同发生氧杂-Michael加成反应得到C-3位构型反转的水解产物1,2-O-异丙叉基-3-C-硝甲基-α-D-呋喃葡萄糖(化合物2′),两种产物化合物2和2′互为C-3差向异构体.通过1H NMR、13C NMR、DEPT-135、1H-1H COSY、gHSQC和gHMBC等核磁共振(NMR)技术,对化合物2′的1H和13C NMR数据进行了全归属. 相似文献
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扁枝藓中锯齿石松烷型三萜的NMR化学位移全归属 总被引:2,自引:0,他引:2
从扁枝藓(Homalia trichomanoides)中分得了三个锯齿石松烷型三萜化合物: 3α-甲氧基-锯齿石松-14-烯-21β-醇(1)、3β-甲氧基-锯齿石松-14-烯-21β-醇(2)和3β-甲氧基-锯齿石松-14-烯-21-酮(3), 应用1D和各种2D NMR实验技术(包括1H-1H COSY, HMQC和HMBC)对化合物结构进行了研究, 对1H和13C化学位移进行了完全归属, 并根据1H NMR中信号的裂分对三个化合物C-3位与1和2的C-21位的立体构型作出了判断 相似文献
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Adam Gryff‐Keller Przemysław Szczeciński Anna Kraska‐Dziadecka 《Journal of Physical Organic Chemistry》2011,24(3):249-256
2‐[2‐Nitro‐4‐(trifluoromethyl)benzoyl]cyclohexane‐1,3‐dione (NTBC) is an active component of nitisinone, a medicine against tyrosinemia type I. Using 1H, 13C and 19F NMR spectroscopy it has been found that in the urine of patients treated with nitisinone two compounds possessing CF3 group are always present. They have been isolated by using TLC technique and identified as 4‐hydroxy‐2‐[2‐nitro‐4‐(trifluoromethyl)benzoyl]cyclohexane‐1,3‐dione and 5‐hydroxy‐2‐[2‐nitro‐4‐(trifluoromethyl)benzoyl]cyclohexane‐1,3‐dione, the latter being previously unknown. The constitution, tautomerism and stereochemistry of these compounds have been thoroughly investigated using 1H and 13C NMR spectroscopy supported by theoretical calculations. Molecular structures have been optimized using density functional theory (DFT) with PBE1PBE functional and 6‐31G* basis set. In NMR parameter calculations, the larger 6‐311++G(2d,p) basis set has been used. At both calculation stages, the polarizable continuum model of the solvent has been employed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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The formation mechanism of the 7×7 reconstruction on annealed Si(1 1 1) surfaces has been demonstrated at the atomic level. In situ observations of unreconstructed regions (‘1×1’) on terraces after rapid quenching to 380 °C were done using scanning tunneling microscopy (STM) with a scanning speed of 1.7 s per frame. In the narrow ‘1×1’ regions, we imaged isolated single-faulted (F) halves of the dimer-adatom-stacking-fault (DAS) structure from “birth” to “death”. During “life”, the isolated single F-halves frequently changed their size. The size changes between odd-sized F-halves always took place through even-sized F-halves of intermediate sizes: 5×5-F′↔6×6-F↔7×7-F′↔8×8-F↔9×9-F′↔10×10-F↔11×11-F′↔12×12-F↔13×13-F′, where the 5×5-F′, 7×7-F′ and so forth are irregular-type structures of the odd-sized F-halves. Even-sized F-halves and the irregular-type structures are necessary in the size changes, whereas the regular-type structures have never been involved. Lifetimes of the 10×10-F, 8×8-F, and 6×6-F at 380 °C are about 10.5, 6, and 2-3 s, respectively, which are much shorter than those of the isolated irregular-type structures of the odd-sized F-halves. With the aid of room temperature STM images of a rapidly quenched surface, we determined the atomic structures of the even-sized F-halves. We have proposed a sequential size change (SSC) model, including undiscovered parts of the size changes ‘1×1’ ↔2×2-F↔3×3-F′↔4×4-F↔5×5-F′, as the formation and decay mechanism of isolated single F-halves in the ‘1×1’ region. The SSC model has the following sequence: ‘1×1’ ↔ 2×2-F↔3×3-F′↔4×4-F↔5×5-F′↔6×6-F↔7×7-F′↔8×8-F↔9×9-F′↔10×10-F↔11×11-F′↔12×12-F↔13×13-F′. It was found by collecting statistics of size-change directions that one of two equivalent sides of the irregular-type structures, which have a mirror symmetry, is involved in the size changes thus indicating that other parts of the F-halves remain unchanged. Based on such findings, we have proposed the atomic processes for bond-rearrangements in the SSC model. The bond-rearrangements proceed along one side of a triangular F-half by breaking the existing dimers and forming new dimers like a “zipper”. Proposed atomic processes of the zipper-like restructuring are illustrated by a ball-and-stick model. The reason for the appearance of the even-sized F-halves and the irregular-type structures of the odd-sized ones is discussed in terms of the energy barrier heights along a reaction path in the size change of single F-halves. 相似文献
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Mansoureh Mousavi Steve S.-F. Yu Der-Lii M. Tzou 《Solid state nuclear magnetic resonance》2009,36(1):24-31
13C cross-polarization/magic-angle spinning (CP/MAS) solid-state NMR spectroscopy has been employed to analyze four vitamin D compounds, namely vitamin D3 (D3), vitamin D2 (D2), and the precursors ergosterol (Erg) and 7-dehydrocholesterol (7DHC). The 13C NMR spectrum of D3 displays a doublet pattern for each of the carbon atoms, while that of Erg contains both singlet and doublet patterns. In the cases of 7DHC and D2, the 13C spectra display various multiplet patterns, viz. singlets, doublets, triplets, and quartets. To overcome the signal overlap between the 13C resonances of protonated and unprotonated carbons, we have subjected these vitamin D compounds to 1D 1H-filtered 13C CP/MAS and {1H}/13C heteronuclear correlation (Hetcor) NMR experiments. As a result, assisted by solution NMR data, all of the 13C resonances have been successfully assigned to the respective carbon atoms of these vitamin D compounds. The 13C multiplets are interpreted due to the presence of s-cis and s-trans configurations in the α- and β-molecular conformers, consistent with computer molecular modeling determined by molecular dynamics and energy minimization calculations. To further characterize the ring conformations in D3, we have successfully extracted chemical shift tensor elements for the 13C doublets. It is demonstrated that 13C solid-state NMR spectroscopy provides a robust and high sensitive means of characterizing molecular conformations in vitamin D compounds. 相似文献
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Parisaponin I 和Parisvietnaside A 的NMR数据分析 总被引:1,自引:0,他引:1
从滇重楼中分离得到2个甾体皂苷,利用1H NMR、13C NMR、1H-1H COSY、HSQC、 HMBC、1D和2D TOCSY等多种核磁共振方法鉴定其结构分别为(25R)-26-O-β-D-吡喃葡萄糖基-3β, 22α, 26-三羟基-呋甾-5-烯- 3-O-α-L -吡喃鼠李糖基-(1→2)[α-L-呋喃阿拉伯糖基(1→4)]-β-D-吡喃葡萄糖苷(1, Parisaponin I)和(25R)-3β, 5α, 6β-三羟基-△7-螺甾烯-3-O-β-D-吡喃葡萄糖基-(1→3)[α-L-吡喃鼠李糖基-(1→2)]-β-D-吡喃葡萄糖苷(2, parisvietnaside A). 对化合物1和2的1H NMR和13C NMR信号分别进行了归属和详细分析,并纠正了文献中的核磁数据归属错误. 化合物2为首次从滇重楼中分离得到. 相似文献
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利用1H NMR、13C NMR、COSY、HSQC和HMBC等多种核磁共振技术,结合MS技术,确认了皂苷Tb的2个糖基化产物的结构,即偏诺皂苷元-3-O-α-D-葡萄糖-(1→3)[α-L-鼠李糖(1→2)]-β-D-葡萄糖苷(1)和偏诺皂苷元-3-O-α-D-葡萄糖-(1→4)-α-D-葡萄糖-(1→3)[α-L-鼠李糖-(1→2)]-β-D-葡萄糖苷(2). 化合物1和2为新化合物,对其1H NMR和13C NMR信号分别进行了全归属和详细分析. 相似文献
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滇黄精中两个呋甾皂苷的NMR研究 总被引:1,自引:0,他引:1
从滇黄精新鲜根茎中分离得到一对立体异构的呋甾皂苷, 利用1D、2D NMR鉴定其结构为: 26-O-β-D-吡喃葡萄糖基25(S)-呋甾-△5(6)-烯-3β, 22, 26-三羟基-12酮基-3-O-β-D-吡喃葡萄糖基(1→4)-β-D-吡喃呋糖苷(1, 25S-kingianoside D)和26-O-β-D-吡喃葡萄糖基25(R)-呋甾-△5(6)-烯-3β-, 22, 26-三羟基-12酮基-3-O-β-D-吡喃葡萄糖基(1→4)-β-D-吡喃呋糖苷(2, kingianoside D). 利用1D、2D NMR对两个呋甾皂苷25位的立体构型进行了确定, 并对其碳、氢信号进行了全归属. 相似文献
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Epoxidation of costunolide (1) yielded parthenolide (3), 1, 10-epoxycostunolide (4), and the cyclization products of 4, santamarin (5), reynosin (6), magnolialide (7) and a 1, 4-epoxyeudesmanolide (8). Reduction of santamarin (5) with sodium borohydride afforded 11, 13-dihydrosantamarin (9) and an eudesmen-triol (10). Reduction of reynosin (6) provided 11, 13-dihydroreynosin (11) and the two eudesman-triols 12 and 13. The structures of the new compounds were elucidated by ID and 2D 1H and 13C NMR spectral methods. 相似文献