一个新的对映-贝壳杉烷型二萜化合物,白叶甲素

一个新的对映－贝壳杉烷型二萜化合物，白叶甲素陈绍农１林中文２陈耀祖１，３＊孙汉董２＊（１兰州大学国家应用有机重点实验室７３００００２中国科学院昆明植物研究所植物化学开放实验室６５０２０４３浙江大学化学系３１００２７）关键词白叶香茶菜唇形科对映－贝壳杉...     

贵州冬凌草的对映－贝壳杉烷二萜化合物

从贵州产冬凌草[Isodon rubescens (Hemsl.) Hera]中分离得到12个6，7－断 裂－7，20－内酯－对映－贝壳杉烷二萜化合物，经波谱分析鉴定了它们的结构， 其中有7个新化合物，分别命名为贵州冬凌草乙素～辛素（guidongnins B～H, 1～ 7)，以及卢氏冬凌草甲素（8）、卢氏冬凌草乙素（9）、贵州冬凌草素（10）、狭 叶香茶菜素(angustifolin, 11)和6－表香茶菜素（6-epiangustifolin, 12)等5个 已知化合物。另外，将作者原命名的贵州冬凌草素（guidongnin, 10）更名为贵州 冬凌草甲素(guidongnin A, 10)，并利用二维核磁区振波谱技术修订了卢氏冬凌草 乙素的结构。     

贵州冬凌草的对映－贝壳杉烷二萜化合物

从贵州产冬凌草[Isodon rubescens (Hemsl.) Hera]中分离得到12个6，7－断 裂－7，20－内酯－对映－贝壳杉烷二萜化合物，经波谱分析鉴定了它们的结构， 其中有7个新化合物，分别命名为贵州冬凌草乙素～辛素（guidongnins B～H, 1～ 7)，以及卢氏冬凌草甲素（8）、卢氏冬凌草乙素（9）、贵州冬凌草素（10）、狭 叶香茶菜素(angustifolin, 11)和6－表香茶菜素（6-epiangustifolin, 12)等5个 已知化合物。另外，将作者原命名的贵州冬凌草素（guidongnin, 10）更名为贵州 冬凌草甲素(guidongnin A, 10)，并利用二维核磁区振波谱技术修订了卢氏冬凌草 乙素的结构。     

冬凌草中的新对映-贝壳杉烷二萜化合物

对河南省济源地区产冬凌草[Isodon rubescens(Hemsl.)Hara]再次进行了深入 的研究，从其叶的乙酸乙酯提取物中分离得到了16个化合物，其中1和2为两个新的 7，20-环氧-对映-贝壳杉烷类二萜化合物，其结构通过波谱分析确定为16（S）-羟 甲基-1α，6β，7β，11β-甲羟基-7α，20-环氧-对映-贝壳杉烷-15-酮（1）和 16（R）-羟甲基-1α，6β，7β，14β-四羟基-7α，20-环氧-对映-贝壳杉烷-15- 酮（2），分别命名为冬凌草已素（1）和庚素（2）；其余的已知化合物分别鉴定 为lasiodonin（3），冬凌草甲素（oridonin，4），乙素（ponicidin），丙素（ rubescensin C），丁素（rubescensin D），牛尾草丙素（rabdoternin C），荛 花香茶菜乙素（wikstroemioidin B），enmenol-1α-O-β-D-glucoside， enmenol，胡麻素（pedalitin），水杨酸，乌索酸，β-谷甾醇和胡萝卜甙。     

ent-贝壳杉烷型二萜化合物的细胞毒活性研究进展

详细地概述了各类天然与合成的ent-贝壳杉烷二萜化合物的细胞毒活性研究进展, 总结和讨论了这类化合物的构效关系、作用机制以及对多种人癌细胞系的选择性, 评述了这类化合物作为抗肿瘤药物的开发潜力, 提出了目前存在的问题与不足, 并对其发展前景和研究方向做出了预测和展望.     

16α-溴-17-羟基对映贝壳杉烷类化合物的合成

贝壳杉烯化合物。在以甜叶菊甙(stevioside,2)为原料在进行对映贝壳杉烯二萜的合成研究中,我们试图合成1及其衍生物3和4以进行抗旱孕活性试验及构效关系的研究。 合成的关键是引进C_(9.11)双键,此可通过C_(17)—OH先引入C_(11)—OH,然后脱羟而成。文献曾报道几乎定量地将17羟基对映贝壳杉—19—酸甲酯(5)转化成C_(11,17)环醚化合物 6(Scheme1)。氧化环     

16α-溴-17-羟基对映贝壳杉烷类化合物的合成

本文合成了7和8两种作为环化前体的16α-溴-17-羟基对映贝壳杉烷类化合物. SeO~2氧化烯丙基化合物10不能得到烯基醛化合物11, 但可得到一个13-乙酰基重排反应产物12.     

瑞香烷型二萜天然产物的合成进展

瑞香烷型二萜类天然产物拥有5/7/6三环骨架的复杂分子结构, 含有多个手性中心, 通常在C3、C4、C5、C9、C13、C14、C20等位置含有手性羟基; 其中, 诸多化合物在C9、C13、C14位置的手性羟基之间形成特定的原酸酯结构. 该类天然产物在抗HIV、抗癌、抗白血病、亲神经性、杀虫、细胞毒性等方面显示显著的生物活性. 瑞香烷型的密集的高氧化数的多环骨架和其引人注目的生物活性吸引了众多研究者的合成兴趣, 尽管迄今为止成功的全合成报道依然鲜见, 但合成化学家对其多环骨架的构建已发展了大量有益的策略和方法, 在此对相关合成工作进行归纳综述.     

舟曲大戟对映—贝壳松烯二萜研究

舟曲大戟(Euphorbia wangii)为大戟属植物,化学成分未见报道。本文报道从中分离得到的4个新对映-贝壳松烯型二萜,命名为舟曲大戟素A、B、C、D。 1 舟曲大戟素A(1)无色结     

14β-甲磺酰氧基对映-贝壳杉二萜重排反应

本文研究了一类具有15-C与16-C单键的14β-甲磺酰氧基对映-贝壳杉烷(烯)(6,7和8)在Zn-EtOH体系中的重排反应, 它们均能重排成6, 7, 5, 5并环系统的化合物3, 12, 13a和13b。8重排时生成一个8-OEt化合物, 为这类化合物重排时经过阳离子中间体提供了一个证据。     

Two New ent-Kaurane Diterpenoids from Isodon xerophilus

In continuation of our research on diterpenoids in the Isodon species, several newcompounds"' were obtained from the leaves oflsodon xerophilus (C. Y. Wu et H. W. Li)H. Hara (Labiatae), a perennial shrub native to Yunnan province. Further fractionation ofthe EtOAc extract led to the isolation of tWo new enl-kauranoids, xerophilusin E (l) andxerophilusin F (2). This paper deals with the structUral elucidation of the newcompounds.Xerophilusin E (l), a minor constitUent, was obtained as p…     

Total Synthesis of Liangshanone

The first total synthesis of liangshanone, a hexacyclic ent-kaurane diterpenoid alkaloid, has been completed. Its intricate cagelike framework was assembled through several key transformations, including an oxidative dearomatization/Diels–Alder (OD/DA) cycloaddition sequence, a tandem alkene cleavage/Mannich cyclization, a Robinson-type annulation, and an intramolecular aldol reaction. Notably, an organocatalytic enantioselective α-hydroxymethylation process allowed the preparation of an enantiomerically enriched tricyclic intermediate that should enable asymmetric access to the target natural product.     

Two New ent-Kaurane Diterpenoids from Isodon adenantha

As a medicinal herb locally used for the treatment of enteritis and dysentery in Yunnan province2, Isodon adenantha (Diels) Hara has been previously studied, which led to the isolation of several ent-kaurane diterpenoids including a new one3-5. In continuation of our research on the bio-active constituents from Isodon species6, two new ent-kaurane diterpenoids, adenanthins B (1) and C (2), were isolated from I. adenantha collected in Dali, Yunnan. In this paper, we report the structural el…     

Three New Diterpenoids from Isodon Eriocalyx

Isodoneriocalyxisknowntoberichinent-kaurenoids.Inspiteofthatmanyent-kaurenoidswereisolated,newent-kaurenoidswerestillisolatedfromcollectionindifferentregions'-,o.FromthedriedleavesofthisspeciescollectedinHeqingcounty,Yunnan,threenewcompounds,eriocalyxinsC-El-3,wereisolated.Inthispaper,wereportthestructureelucidationofthesenewcompoundsbyspectralanalysis.EriocaIyxinClC22H2sO7(HRMS4O4.l825calc4O4.1835),ElMS(7OeV)In/z(reI.Int%)t4O4[M1 (lO),386[M-H2O] 'lO),368IM-2H,O] (2O),344(l00),32…     

Divergent Total Synthesis of Atisane‐Type Diterpenoids

Atisane‐type diterpenoids are the principal constituent of tetracyclic C₂₀‐diterpenoids, widely isolated from the plant kingdom with varying degrees of structural complexity and pharmacological activity. The tetracarbocyclic system with the unique bicyclo[2.2.2]octane skeleton of this natural product family has generated interest within the synthetic community. Divergent total synthesis is an effective tactic to synthesize several atisane‐type diterpenoids using structural interconversion from a common intermediate. This account summarizes the divergent total synthesis of atisane‐type diterpenoids.     

A Biomimetic Synthesis of Sacculatane Diterpenoids

The biomimetic synthesis of sacculatane‐type epimeric compounds 14a and 14b is reported. The key synthetic step is the low‐temperature superacidic cyclization of (all‐E)‐ω‐acetoxygeranylgeraniol 12 obtained in nine steps from geranyllinalool ( 13 ). The 19‐acetoxysacculata‐7,17‐dien‐11‐ol ( 14a ) could be an important and convenient starting compound for the synthesis of other sacculatane diterpenoids.     

Four New Diterpenoids from Isodon leucophylla

IsodonleucoPhyll(Dunn)Hara(Labiatae),distributedinthenorthwestareaofYunnanProvince,isusedasfolkmedicineforitsantibacterialandanti-inflanimatoryactivitybylocalpractitioners'.Fromtheleavesofthisplant,fournewent-kauranetypediterPenoids,baiyecrystalA'C1'3andePi-baiyecrystalC4,wereisolated.Thispaperpresentstheirsimctureelucidation.BaiyecrystalA1C26H34O1owasdeterminedbyHRMS(5O6.2157,calc5o6.2l52).Itsmassspectrumshowedthatthemolecularion(wt5O6)was58amumorethanthatofeffusaninD5',aknownkaureno…     

Total Synthesis of Ileabethoxazole,Pseudopteroxazole, and seco‐Pseudopteroxazole

The total syntheses of ileabethoxazole, pseudopteroxazole, and seco‐pseudopteroxazole, three antituberculosis diterpenoids that had been isolated from Pseudopterogorgia elisabethae, were accomplished in a collective fashion. A cascade alkyne carbopalladation/Stille reaction was exploited to construct a triene precursor with suitable geometry. A fully substituted arene was then assembled through a key 6π electrocyclization/aromatization sequence, and served as an advanced common intermediate. Two radical cyclizations led to the formation of the five‐ and six‐membered rings of ileabethoxazole and pseudopteroxazole, respectively, with the desired stereochemistry, and a straightforward side‐chain elongation delivered seco‐pseudopteroxazole.     

Total Synthesis of Maoecrystal P: Application of a Strained Bicyclic Synthon

A new strategy was devised for the total synthesis of highly oxidized ent‐kauranoids. A highly regio‐ and diastereoselective intermolecular Diels–Alder cycloaddition involving a diene embedded in a substituted bicyclo[4.1.0] skeleton was used to assemble all carbon centers but C17 of the target molecule at an early stage of the synthesis. Subsequent synthetic steps, including redox manipulations, SmI₂‐mediated cyclization, and isomerization reactions, afforded the antitumor natural product maoecrystal P.