Preparation of [1,2,3,4,5-13C5]-5-Amino-4-oxopentanoic Acid (ALA)− Design of a Synthetic Scheme to Prepare Any13C- and15N-Isotopomer with High Isotopic Enrichment
作者:Prativa Bade Shrestha-Dawadi、Johan Lugtenburg
DOI:10.1002/ejoc.200300408
日期:2003.12
5-Amino-4-oxopentanoic acid (5-aminolevulinic acid) is a precursor in the biosynthesis of the biologically active porphyrins such as chlorophyll, bacteriochlorophyll, heme, etc. These systems are central in photosynthesis, oxygen transport, electron transport, etc. In this paper we describe a simple scheme to prepare any isotopomer of 5-aminolevulinic acid in a few steps in high yield. Using a similar scheme, levulinic
Quantitation of Key Aroma Compounds in Fresh, Raw Ginger (<i>Zingiber officinale</i> Roscoe) from China and Roasted Ginger by Stable Isotope Dilution Assays and Aroma Profiling by Recombination Experiments
作者:Tanja Schaller、Peter Schieberle
DOI:10.1021/acs.jafc.0c06733
日期:2020.12.23
with high OAVs to the overall aroma profile of the fresh, raw ginger. An aroma recombinate prepared with 20 reference compounds in the same concentrations as determined in the ginger sample successfully matched the overall aroma profile. In the roasted ginger, 1,8-cineol and myrcene remained the most odor-active compounds, however, the increase in some odorants, for example, in geraniol and (Z)-2-decenal
最近在生姜和烤姜中鉴定出的 20 种主要气味物质通过稳定同位素稀释测定法进行了定量,其中 6 种测定法是新开发的。气味活性值(OAV;浓度与气味阈值之比)显示 1,8-桉树脑(类桉树)的最高值为 65 000,其次是月桂烯(类天竺葵),其 OAV 为 19 000计算出来的。此外,( R )-香茅醛、香叶醛、( R )-芳樟醇、( E )-异丁香酚和( E )-2-辛烯醛为新鲜生姜的整体香气贡献了高 OAV。使用与生姜样品中测定的浓度相同的 20 种参考化合物制备的香气重组成功地匹配了整体香气特征。在烤姜中,1,8-桉树脑和月桂烯仍然是最具气味活性的化合物,然而,一些气味剂的增加,例如香叶醇和( Z )-2-癸烯醛,与新形成的焦糖结合在一起,类似于 4-羟基-2,5-二甲基-3(2 H )-呋喃酮(焦糖样)和 3-(甲硫基)丙醛(马铃薯样)的气味,很可能是由热处理引起的香气特征的差异。基于
A Simple Efficient Synthesis of [23,24]-13C2-Labeled Bile Salts as NMR Probes of Protein–Ligand Interactions
作者:Gregory P. Tochtrop、Gregory T. DeKoster、David P. Cistola、Douglas F. Covey
DOI:10.1016/s0960-894x(01)00763-6
日期:2002.2
The synthesis of [23,24]-(13)C(2)-labeled bile salts is achieved through a steroidalsidechaindegradation and isotopic regeneration strategy. Three common bile acids were degraded to the corresponding C(22 )aldehyde by an oxidative decarboxylation followed by ozonolysis. The sidechain was subsequently regenerated via a Horner-Emmons reaction using an ylide generated from (13)C(2)-labeled bromoacetic
Two new cytotoxic macrolides, amphidinolides R (1) and S (2), were isolated from the cultured marinedinoflagellateAmphidiniumsp. and their structures including absolute configuration were elucidated on the basis of spectroscopic data as well as chemical experiments. In a feeding experiment of 13C-labeled succinic acid into a culture of Amphidiniumsp., no enrichment of the 13C NMR signal intensity
两种新的细胞毒性大环内酯类,两性内酯R(1)和S(2),从培养的海洋鞭毛鞭状菌Amphidinium sp中分离出来。根据光谱数据和化学实验阐明了它们的结构,包括绝对构型。在将13 C标记的琥珀酸进料到Amphidinium sp。的培养实验中,未观察到任何碳的安非他命J(3)(该鞭毛中最丰富的大环内酯)的13 C NMR信号强度富集。
Synthesis of (12,13-13C2)retinal and (13,1413C2)retinal: A strategy to prepare multiple-13C-labeled conjugated systems
作者:M. Groesbeek、G. A. Rood、J. Lugtenburg
DOI:10.1002/recl.19921110307
日期:——
(12,13-13C2)Retinal, (13,14-13C2)retinal, (19-13C)retinal and (20-13C)retinal (1) were prepared in a simple fashion in high yield via a consecutive strategy. The key step is the reaction of a N-methoxy-N-methylamide with an alkyllithium or a Grignard reagent. The preparation of the required N-methoxy-N-methylamide is discussed. In this scheme, only three commercially available 13C-labeled starting