一个新的紫杉烷二萜化合物的NMR研究

从云南红豆杉树皮中分离得到一个新的紫杉烷二萜化合物，用核磁共振１Ｈ谱、１３Ｃ谱、ＤＥＰＴ、１Ｈ－１ＨＣＯＳＹ、ＨＭＱＣ、ＨＭＢＣ谱，辅以其它谱的数据确定其为具５／７／６元环的７，９－ｄｉｄｅａｃｅｔｙｌｔａｘａｙｕｎｔｉｎ，指定了１Ｈ和１３Ｃ谱所有谱线的归属。     

蒺藜草中一个新的六糖甾体皂甙结构的NMR研究

从蒺藜草中分离得到一个新的六糖甾体皂甙，利用NMR方法，特别是2D NMR技术，确定了它的化学结构3－O－{β-D－吡喃木糖基－（1→3)-[β-D吡喃木基－（1→2)]β-D－吡喃葡萄糖甙－（1→4）－[α-L吡喃鼠李糖基－（1→2）]－β-D吡喃半乳糖基}－22－甲氧基－26－O{β-D－吡喃和葡萄糖基}－蒺藜皂甙元。     

水峰调制下的3,4-Seco-olean-11,13-dien-4,15α,22β,24-tetraol-3-oic Acid的NMR结构解析

对海南半红树植物黄槿(Hibiscus tiliaceus)内生菌中提取的一个新化合物进行核磁共振结构解析的研究. 在核磁共振测试时发现水峰信号与部分样品信号发生了重叠, 直接影响了该化合物谱图数据的分析. 本工作通过实验确证了在氘代二甲亚砜(DMSO-d₆)溶剂中水峰化学位移与含水量之间的变化规律. 依据该规律, 利用定量加入纯水的方法对实际样品中的水峰信号进行了调制, 解决了水峰信号与样品信号的重叠问题, 得到了较理想的¹H NMR, ¹³C NMR一维谱和COSY, HMQC, HMBC等二维谱. 利用核磁共振提供的信息完成了对新化合物结构的解析, 确定该化合物为齐墩果烷三萜类化合物3,4-seco-olean-11,13-dien-4,15α,22β,24-tetraol-3-oic acid.     

选择性NMR新技术用于新的3, 28-双糖链三萜皂苷的结构研究

从中药川续断根部的乙醇提取物中分得一个新的三萜皂苷。经过测定,它为:3-O-[α-L-吡喃鼠李糖(1→3)][-β-D-吡喃葡萄糖(1→4)]-β-D-吡喃葡萄糖(1→3)-α-L-吡喃鼠李糖(1→2)-α-L-吡喃阿拉伯糖-常春藤苷元-28-O-β-D-吡喃葡萄糖(1→6)-β-D-吡喃葡萄糖酯苷。研究表明,采用一维SEMDY、旋转坐标NOE差谱和选择性远程DEPT核磁共振新技术相结合的方法测定糖链结构不需要对该化合物1进行化学降解或衍生化,方法简便、快速,测定结果可靠,每个糖基的信号可以分辨和明确归属。     

一种金属洗涤剂的NMR分析

由于精细化工行业的迅速发展,作为“工业味精”的表面活性剂,已广泛进入日化、轻工、纺织、建筑、石化、金属加工等生产领域,对其的分析也显得日益重要。表面活性剂的分析历来是比较困难的课题之一,而通过核磁共振(NMR)进行定性和定量的文献则更少[1]。本文利用NMR为多种表面活     

C_2对称二氨基二醇硼烷的不对称还原机理──I.新型双活性中心催化剂结构的 in situ NMR研究

采用~１Ｈ,~１３Ｃ ＮＭＲ,~１１Ｂ ＮＭＲ极化转移实验ＤＥＰＴ１３５,ＤＥＰＴ９０和二维ＮＭＲ实 验以及ＩＲ等技术,对用于潜手性酮类不对称硼烷还原的二氨基二醇配体及其衍生物进 行了鉴定,并对其与硼烷原位形成的催化剂结构进行了 ｉｎ ｓｉｔｕ ＮＭＲ研究,发现了催化 剂在反应溶液中的结构转化现象,确定了催化剂的结构为新型的双活性中心催化剂 ──双噁唑硼烷．     

NMR对苯并噁嗪类化合物结构的研究

利用'H、'13CNMR谱及HMBC、HMQC二维谱对10种苯并噁嗪类化合物的结构进行了研究,初步得出了它们的NMR谱特征,分析了化学位移的影响因素。     

日本续断中新的双糖链三萜皂苷的结构研究

从日本续断根部的乙醇提取物中分得一个新的三萜皂苷。经过测定,它为：3-O-α-L-吡喃鼠李糖(1→3)-β-D-吡喃葡萄糖(1→3)-α-L-吡喃鼠李糖(1→2)-α-L-吡喃阿拉伯糖9常春藤苷元－28-O-β-吡喃葡萄糖酯苷)。结果表明,采用一维SEMDY,旋转坐标NOE差谱和选择性远程DEPT核磁共振新技术相结合的方法测定糖链结构不需要对化合物进行化学降解或衍生化,方法简便、快速,测定结果可靠,每个糖基的信号可以分辨和明确归属。     

C2对称二氨基二醇硼烷的不对称还原机理--Ⅰ.新型双活性中心催化剂结构的in situ NMR研究

采用1H,13C NMR,11B NMR极化转移实验DEPT135,DEPT90和二维NMR实验以及IR等技术,对用于潜手性酮类不对称硼烷还原的二氨基二醇配体及其衍生物进行了鉴定,并对其与硼烷原位形成的催化剂结构进行了in situ NMR研究,发现了催化剂在反应溶液中的结构转化现象,确定了催化剂的结构为新型的双活性中心催化剂--双噁唑硼烷.     

Synthesis and spectral study of a novel distamycin conjugate

The ¹H and ¹³C NMR resonances for a novel distamycin conjugate, 3‐[1‐methyl‐4‐[1‐methyl‐4‐[1‐methyl‐4‐[N¹‐[5‐methyl‐2,4(1H,3H)pyrimidinedione]acetylamino]pyrrole‐2‐carboxamido]pyrrole‐2‐carboxamido]pyrrole‐2‐carboxamido]propionamidine hydrochloride ( 1 ), were assigned, using the concerted application of one‐ and two‐dimensional NMR techniques including nuclear Overhauser effect difference, DEPT, HMQC and HMBC experiments. Copyright © 2003 John Wiley & Sons, Ltd.     

Structural Study on NMR and X-Ray of Lactucopicrin—A Guaianolide Ester

The guaianolide ester is a potent inhibitor of cancer cells. Lactucopicrin, a guaianolide, shows analgesic, antitussic, and sedative activities. In order to investigate its structure, ¹H and ¹³C NMR and 2D NMR have been carried out at a proton field strength of 400 MHz and a carbon field strength of 100 Mhz in DMSO-d ₆ at 20°C. Resonances for all protons and carbons have been assigned. The results of HMQC and HMBC experiments suggest that the structure of lactucopicrin is as shown in Fig. 1. Its stereostructure is verified by the X-ray experiment. ¹H and ¹³C NMR of lactucopicrin are reported. Its 2D NMR and X-ray are reported for the first time.     

Synthesis and complete assignment of the 1H and 13C NMR signals of new acetamido and aminoflavonoid derivatives

The complete ¹H and ¹³C NMR assignment of 9 acetamidochalcones, 18 acetamidoflavones, 18 aminoflavones, 9 acetamidoflavonols and 9 aminoflavonols has been performed using one‐ and two‐dimensional NMR techniques including COSY, HMQC and HMBC experiments. Copyright © 2010 John Wiley & Sons, Ltd.     

Structure elucidation of an unexpected product from dehydration of a beta-hydroxyketone

The structure of an unexpected compound from the dehydration of an aldol addition product has been determined using 1-D and 2-D NMR techniques. This reaction is the last step in a new synthetic approach to the galanthan ring system. Complete 1H and 13C NMR assignments for two synthetic precursors are also reported.     

1H and 13C NMR signal assignments of some new N,N′‐diacyl proflavine derivatives

The complete ¹H and ¹³C NMR signal assignments of 23 new N,N′‐diacyl proflavine derivatives were achieved using one‐ and two‐dimensional experiments (DEPT, HMQC and HMBC). Copyright © 2009 John Wiley & Sons, Ltd.     

Structural elucidation of a new delta2-pyrazoline derivatives using 1H and 13C NMR spectroscopy

This paper describes the unequivocal structural elucidation of a new kind of Delta2-pyrazoline derivatives carried out by means of monodimensional 1H and 13C NMR spectroscopies, bidimensional ones such as HMBC and HMQC experiments, and NOEDIFF effects. Conformational analysis of this molecule agrees very well with the experimentally NOEDIFF effects found.     

Two new dammarane triterpenoids from Kageneckia angustifolia D. Don

Two new dammarane triterpenoids, 20R,21-epoxydammar-24-ene-3,23-dione and 20R,21-epoxy-3beta-hydroxydammar-24-ene-23-one have been isolated from the aerial parts of Kageneckia angustifolia D. Don, Rosaceae, along with the previously reported triterpenoids oleanolic acid and 3beta-(beta-D-glucosyloxy)-16alpha,23alpha-epoxycucurbita-5,24-dien-11-one and the phenolic prunasin. The structures of these compounds were established by MS, 1D- and 2D-NMR experiments, and the structure of the new compounds were confirmed by X-ray diffraction analysis.     

Synthesis and NMR studies of novel chromone‐2‐carboxamide derivatives

Chromones are heterocyclic compounds of natural or synthetic origin that possess relevant pharmacological activities. Versatile functionalization of the chromone nucleus allows attaining of a chemical diversity suitable to perform structure–activity relationships in drug discovery and development programs. Accordingly, the synthesis and identification of novel chromone carboxamide derivatives with electron‐donating and electron‐withdrawing substituents in different positions of the exocyclic ring are reported in this work. Their complete structural characterization was performed using one‐dimensional and two‐dimensional resonance techniques. The data acquired are useful for a prompt analysis of related compounds that encompass our integrated medicinal chemistry sketch. Copyright © 2013 John Wiley & Sons, Ltd.     

Identification of modified natural porphyrin isomers: 1H and 13C NMR assignments by NOESY and reverse heteronuclear shift correlation

The efficiency of two-dimensional homonuclear ¹H ¹H NOE spectroscopy in characterizing and fully assigning the ¹H NMR spectra of several isomers of meso- or ring-substituted deuteroporphyrins is demonstrated. The carbon resonances of the skeleton and the substituents were fully assigned using two-dimensional reverse heteronuclear shift correlation spectroscopy.     

1H and 13C spectral assignment of symmetrical bis[(4-aminosubstituted)quinolinium] derivatives

1H and 13C NMR spectroscopic data of both the quinolinium ring and the spacers for 32 symmetrical bisquinolinium compounds were assigned by a combination of one- and two-dimensional experiments (DEPT, HMBC, HMQC). The compounds have electron-releasing groups at position 4 of the quinolinium ring, with several arylalkyl linkers such as the 3,3'-, 4,4'-bis(methylene)biphenyl and 4,4'-bis(methylene)bibenzyl moieties.