Oxidation of the Norditerpenoid Alkaloids Isotalatizidine and 6-Epiforsticine

Oxidation of 1 with KMnO4 in acetone-H2O (1:1) for 1h gave nevadenine 2 (38%). But, 3 was formed in 98% yield when prolonging time and raising temperature (40℃). Reaction of 1 and 10 with Conforth reagent afforded the ketones 11 (55%), 12 (30%), and 13 (13%), 14 (20%), respectively. While oxidation of 7 and 15 with a variety of the oxidizing agents gave 17 only in low 20% of yield besides the minor 16. In addition, 1 was converted to 2 by the fungi Curvularia lunata.     

Oxidation of the Norditerpenoid Alkaloids Isotalatisidine and 6-Epiforsticine

Inpreviousworksonmodificationsofnorditerpenoidalkaloids,wereportedsomeimportantreactionssuchasN-deethylationandpreparationsoftheimmesand7,17-secoderivatives'.NowwewishtorepoFtoxidationofthenorditerpenoidalkaloidsisotalatizidineand6-epiforsticine.Oxidationofnorditerpenoidalkalnidshavinganla-hydroxylgroupwithreagentssuchasKMnO.K,Fe(CN),,OsO.,Ag,OandNBSaffordedcompoundswithanO,Nmixedacetalsystems=.Thus,treatmentofisqtalatizidineIwithKMnO.inacetone-H,O(5;1)forIhgavetheknowncompoundnevade…     

Novel Product and Its Derivatives from the Reaction of Lappaconitine with HIO_4

Lappaconitine l, a bisnorditerpenoid alkaloid, was isolated from many plants ofAconitum and Delphinium species such as A. barbatum var. puberulum, A.sinomontanuml' 2. It is now used in the clinical practice as an analgesic in China', andantiarrhythmic drugs in Uzbekistan4' 5. In our attempts to prepare the 10-oxygenatedderivatives by treating lappaconitine I with HIO. followed by bromination, unexpectedby-products were obtained in modest yields. This communication described the isolationan…     

Preparation of the N,19-seco Norditerpenoid Alkaloids from Norditerpenoid Alkaloid Yunaconitine

The synthesis of a new N,19-Seco norditerpenoid alkaloid 7 bearing nitro group from yunaconitine 1 as the starting material through a series of steps was described.     

Protein Engineering of an Artificial P450BM3 Peroxygenase System Enables Highly Selective O-Demethylation of Lignin Monomers

The O-demethylation of lignin monomers, which has drawn substantial attention recently, is critical for the formation of phenols from aromatic ethers. The P450BM3 peroxygenase system was recently found to enable the O-demethylation of different aromatic ethers with the assistance of dual-functional small molecules (DFSM), but these prepared mutants only have either moderate O-demethylation activity or moderate selectivity, which hinders their further application. In this study, we improve the system by introducing different amino acids into the active site of P450BM3, and these amino acids with different side chains impacted the catalytic ability of enzymes due to their differences in size, polarity, and hydrophobicity. Among the prepared mutants, the combination of V78A/F87A/T268I/A264G and Im-C6-Phe efficiently catalyzed the O-demethylation of guaiacol (TON = 839) with 100% selectivity. Compared with NADPH-dependent systems, we offer an economical and practical bioconversion avenue.     

草乌中二萜类生物碱的电喷雾串联质谱研究

利用电喷雾质谱技术对传统中药草乌中的二萜类生物碱进行直接分析鉴定.通过实验数据并对比文献发现,草乌中含有单酯型、双酯型、三酯型和脂类等共4种类型生物碱,其中三酯型和脂类生物碱在草乌中为首次发现.由于这些生物碱的结构相似,在电喷雾串联质谱中碎裂方式相同,因此根据电喷雾串联质谱结果确定了这些生物碱的结构.     

Two new C18-norditerpenoid alkaloids from Aconitum delavayi

Further phytochemical investigation of the unique C18-norditerpenoid alkaloids from the roots of Aconitum delavayi Franch ledto the isolation of two new norditerpenoid alkaloids,delavaconitine F 1 and delavaconitine G 2.Their structures were determinedfrom spectroscopic evidence.     

滇乌碱类似物的碳谱

本文报告11种非天然产的去甲二萜生物碱滇乌碱(yunnaconitine12)的类似物(1-11)的碳谱研究,并归纳总结某些取代基的位移规律。所有这些化合物都是在此类化合物化学研究中分离并鉴定的。而且均为新的人工化合物。这些研究将有助于此类化合物的结构测定。     

Analysis of Norditerpenoid Alkaloids. Extracted from Aconitum sinomantanum Nakai by Electrospray Ionization Tandem Mass Spectrometry

Introduction AconitumsinomantanumNakai(GaowutouinChi nese)isdistributedinthenorthwesternareaofChina,anditsroots(RAS)areexternallyusedasakindof folkmedicineinChina.Themainactiveconstituentsof RASarenorditerpenoidalkaloids.Themajoralkaloid,lappaconitine,was…     

Modifications of Norditerpenoid Alkaloids:Ⅲ. Preparation of 7 ,17-seco Yunnaconitine Derivatives via Rearrangement of Chloroamine

Inourinvestigationofmoditicationofthenorditerpenoidalkaloids.cleavageoftheC(17)-C(7)bondsisthekeyreaction.Ref.[I]gaveasystematicsunlnling-upaboutthecleavages.illcludingpyrolysisof,opoxides=.pc'rolysis-reduction;,photolysis-reduction;.rearrangement-reduction',oxidation-reduction3'6alldneighboringgroupparticipation'.11ox'rever.mostofthemledtothecomplicatedproducts'.withlowyieldsordifficultpuritlcation.Inthispaper.wereportindetailsonthecleavageoftheC(l7)-C(7)bondsintheaconitine-typenorditerpeno…     

Selective O-demethylation during bromination of (3,4-dimethoxyphenyl)(2,3,4-trimethoxyphenyl)methanone

(3,4-Dimethoxyphenyl)(2,3,4-trimethoxyphenyl)methanone was synthesized and its bromination was investigated in different conditions. Nine new products (bromophenol derivatives) were isolated in the reactions. These bromophenol derivatives were obtained by selective O-demethylation in its bromination with bromine. The products and their formations were discussed.     

钩吻素子合成方法的研究——Ⅱ.异喹宁环体系烯丙位的氧化反应

钩吻素子(koumine)是植物钩吻Geese-mium elegans Benth中的一个主要生物碱,迄今未见其全合成报道。在我们设想的合成路线中,首先通过下列反应合成了endo构型的二元酸(4)。为了能通过Fischer吲哚合成反应进一步引入假吲哚环,4的异喹宁环8位应当是一个乙酰基。本文报道异喹宁环烯丙位的氧化工作。     

Biodestruction of Lignins by the Basidiomycete Pleurotus ostreatus

The depolymerization, demethoxylation, and oxidation of lignin by the common oyster mushroom (Pleurotus ostreatus)is demonstrated     

Total synthesis of(+)-lentiginosine via a key Au catalysis

Total syntheses of(+)-lentiginosine and its 8a-epimer using a gold-catalyzed oxidative cyclization as the key step were realized.The gold chemistry,reported previously in a 4+2 synthesis of piperidin-4-ones,tolerates functionalized structures and is compatible with several protecting strategies albeit with low diastereose lectivities.     

Isolation and structure of rosicine from Catharanthus roseus

An investigation of the alkaloidal constituents of the leaves of Catharanthus roseus has led to the isolation of a new alkaloid, “rosicine”, to which structure (1) has been assigned on the basis of spectroscopic studies. Two other alkaloids isolated have been identified as 14, 15-dehydroepivincadine and 19-hydroxytabersonine.     

Alkaloids from the Roots of Saccopetalum prolificum

In recent years, an increased interest in the phytochemistry of the Annonaceae has beensparked by the isolation of the antileukemic Annonaceous acetogenin'. Saccopela/umprolificllm (Chun el How) Tsiang (Allnonaceae) is an evergreen tree distributed inHainan Province, P. R. China. The ethanolic extract of the plant exhibited cell growthinhibitory activity (20 ig/ml) against LIZ10 lymphocytic leukemia. A new alkaloid,prolifine (l), was isolated from the roots of S. proldicum, in addition t…     

NaIO_4-Catalyzed Bromination of the Aromatic Ring of Lappaconitine

Lappaconitine 1, a bisnorditerpenoid alkaloid, was isolated from many plants of Aconitum species such as A. barbatum var. pulerulum and A. sinomontanum (Ranunculaceae)1-3, and used clinically for treatment of analgic disease as a nonaddicted drug in China4, and as an antiarrythmic in Uzbekistan5. In order to search for high activity, low toxicity compounds, we have carried out the structure modifications of lappaconitine. In this case, an attempt to induce the oxygenated group at C-10 in 1 b…     

Synthesis of A Natural Cytotoxic Alkaloid Artabotrine and its Analogue

Artabotrine 1 (Figure 1) was isolated from Artabotrys zeylanicus Hook.f. & Thoms., an endemic mainly in Sri Lanka1. The spectral data and single crystal X-ray analysis indicated that artabotrine is a novel and comparatively rare alkaloid characterized with N-methoxylated 4,5-dioxoaporphine, since most of the reported 4,5-dioxoaporphines are N-methylated or no substituted2-11. This highly oxidized aporphine alkaloid was found to possess notable inhibitory activity on P-388 leukemia cell lin…