Plant Orthoesters

Liao, Shang‐Gao; Chen, Huadong; Yue, Jian‐Min

doi:10.1021/cr0782832

Cited by 176 publications

(138 citation statements)

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“…[10][11][12] The HMBC correlations from a downfield signal at d suggesting the orthoester moiety in 1 is an isobutylate group, rarely encountered in phragmalin orthoesters. 2,16) A proton signal at d H 3.28, no correlation with carbon observed in HSQC spectrum, showed HMBC correlations with carbon signals at d C 84.6 (C-1), d C 48.2 (C-10), and d C 40.3 (C-29), which suggested that it is a hydroxy proton singal and attached at C-1. The presence of the OH group at C-1, the weak HMBC correlation from H-30 (d H 4.51) to the orthoester carbon, and the chemical shifts of C-2 (d C 75.2), C-8 (d C 83.8), C-9 (d C 85.4) and C-30 (d C 78.0) confined the location of the orthoester group to C-8/C-9/C-30.…”

Section: Resultsmentioning

confidence: 91%

“…1) Phragmalin-type limonoid orthoester is an important branch of orthoesters with phragmalin limonoid as the basic skeleton, discovered exclusively from the genera of Meliaceae. 1,2) The genus chukrasia (Meliaceae) 3) was revealed to be a rich resource of structure diversified phragmalin-type limonoids as well as orthoesters. [4][5][6][7][8][9] Our previous study on phragmalin-type limonoids from Chukrasia tabularis var.…”

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Phragmalin-Type Limonoid Orthoesters from Chukrasia tabularis var. velutina

Luo

Wang

et al. 2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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Regular ArticleThe orthoester group contains a carbon atom bearing three alkoxy or aryloxy groups, and, combined with additional attachments and/or rings, constructs often various structural skeletons of stereochemical complexity, such as daphnane diterpenoids, phragmalin-type limonoids, and bufadienolide and ergostanoid steroids, some of which showed anticancer, antifeedant, and insecticidal activities. 1)Phragmalin-type limonoid orthoester is an important branch of orthoesters with phragmalin limonoid as the basic skeleton, discovered exclusively from the genera of Meliaceae.1,2) The genus chukrasia (Meliaceae) 3) was revealed to be a rich resource of structure diversified phragmalin-type limonoids as well as orthoesters. [4][5][6][7][8][9] Our previous study on phragmalin-type limonoids from Chukrasia tabularis var. velutina afforded a series of 16-norphragmalin limonoids 10,11) and a new class of C-15-acyl phragmalin-type limonoids orthoesters.12) In our present research, nine new phragmalintype limonoid orthoesters, tabulalides F-N (1-9), together with three known compounds, tabulalides C and D and tabularisin N (10-12), were isolated from the ethanol extract of this plant. The structures of these new compounds ( Fig. 1) were elucidated using extensive 2D spectroscopic technologies, and the absolute configurations of 1 and 2 were determined by circular dichroism (CD) exciton chirality method.1,13) Tabulalide F (1) possesses a rare orthoisobutylate moiety in phragmalin limonoid orthoesters.Anticancer activity is the important aspect of limonoids from Meliaceae, and a precursor of phragmalin limonoid was found to be a novel Hsp90 inhibitor.14,15) So, we evaluated cytotoxic activity of compounds 2-12 against five human cancer cell lines, MCF-7 (human breast cancer), Hela (human cervical cancer), SGC-7901 and BGC-823 (human gastric cancer), HepG2 (human liver cancer). The preliminary results indicated that compund 2 exhibts moderate cytotoxic activity against MCF-7 with IC 50 value of 20.4 mmol/l and weak cytotoxic activity against SGC-7901 with IC 50 value of 63.4 mmol/l. The other isolates show weak cytotoxic activity or noncytotoxic (IC 50 Ͼ100 mmol/l) anainst other cancer cell lines. Herein, the isolation, structural elucidation, and cytotoxic activity of these isolates were reported. Results and DiscussionTabulalide F (1) was isolated as white amorphous powder. Its molecular formula was established to be C 38 H 44 O 17 by the high resolution-electrospray ionization (HR-ESI)-MS ion at m/z 783.2470 [MϩNa] ϩ (Calcd: C 36 H 44 O 16 Na, 783.2471). The IR absorption bands at 3499, 1737 and 1641 cm Ϫ1 suggested the presence of hydroxyl, ester, and a,b-unsaturated ester carbonyl groups. The data from decoupling and subsequent 1D-and 2D-NMR studies ( 1 H, 13 C, heteronuclear multiple bond connectivity (HMBC), heteronuclear single quantum coherence (HSQC), and rotating frame Overhauser enhancement spectroscopy (ROESY)) (Fig. 2) Nine new phragmalin-type limonoid orthoesters, tabulalides F-N (1-9), together with th...

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Section: Resultsmentioning

confidence: 91%

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Phragmalin-Type Limonoid Orthoesters from Chukrasia tabularis var. velutina

Luo

Wang

et al. 2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…[1][2][3] Daphnane is a major class of diterpenes and has received considerable attention due to its important pharmacological activity. [4][5][6] Resiniferatoxin (1, Fig. 1), a representative daphnane diterpene, is the irritant in the latex of Euphorbia resinifera.…”

Section: Introductionmentioning

confidence: 99%

Radical-Mediated Three-Component Reaction: A Study toward the Total Synthesis of Resiniferatoxin

Urabe

2015

CHEMICAL & PHARMACEUTICAL BULLETIN

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This review summarizes the efforts to develop a radical-mediated three-component reaction and its application to a convergent approach to synthesize the 5/7/6-tricyclic framework (ABC-rings) of the densely functionalized dephnane diterpene, resiniferatoxin. The α-alkoxy bridgehead radical species, which was designed as the radical donor of the three-component reaction, was generated from O,Se-and O,Te-acetals under two different conditions. The generated α-alkoxy bridgehead radical effectively underwent the threecomponent reaction with α,β-unsaturated ketones and allyltributyltin/aldehyde under each of the conditions, giving rise to a wide variety of multiply functionalized 2,3-trans disubstituted cyclopentenone moieties. One of the established reactions was utilized as the key assembling reaction of the ABC-tricyclic framework of resiniferatoxin. The reaction of the bridgehead radical of the highly functionalized 6-membered C-ring, the 5-membered A-ring, and an allyltributyltin derivative effectively produced the C4-branched AC-rings. The last B-ring was constructed from the coupling adduct in two steps through the 7-endo cyclization, delivering the tricyclic framework possessing the correct C8 and 9-stereocenters of resiniferatoxin. The present methods demonstrate the power of the three-component reaction using an α-alkoxy bridgehead radical in a convergent approach to the complex architectures of daphnane diterpenes.

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“…Keywords daphnane; diterpenoid; (＋)-resiniferatoxin; total synthesis; synthetic methodology 1 引言瑞香烷型二萜类天然产物主要分布在瑞香科和大戟科植物中, 具有 5/7/6 三环骨架 1, 通常在 C3、C4、 C5、C9、C13、C14、C20 位置有羟基, 在 C9、C13、 C14 具有特定的原酸酯结构. 根据 B 环和 C 环的氧化形式以及 A 环的取代形式, 可将已知的瑞香烷型二萜天然产物(图 1)分为六类 [1] : daphnetoxins 2、12-hydroxydaphnetoxins 3、1-alkyldaphnanes 4、resiniferonoids 5、 genkwanines 6 和 rediocides 7; 其中, daphnetoxins 通常在 A 环具有 α-β 不饱和酮结构, 且 B 环具有 C5β 羟基、 C20 羟基、C6α-C7α 环氧结构; 12-hydroxydaphnetoxins 相对于 daphnetoxins 在 C12 处多一个含氧官能团 OR, 并且 OR 通常为酰氧基; 1-alkyldaphnanes 通常具有饱和的 A 环, 并且原酸酯烷基链末端和 A 环 C1 之间具有一个大环; resiniferonoids 相对于 daphnetoxins 而言, A 环具有 α-β 不饱和酮结构, B 环 C5 为亚甲基且 C6-C7 之间为双键, C20 为羟基或者酰氧基; genkwanines 通常在 B 环 C6-C7 之间具有双羟基, 并且饱和 A 环 C3 以及 B 环 C20 …”

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“…根据 B 环和 C 环的氧化形式以及 A 环的取代形式, 可将已知的瑞香烷型二萜天然产物(图 1)分为六类 [1] : daphnetoxins 2、12-hydroxydaphnetoxins 3、1-alkyldaphnanes 4、resiniferonoids 5、 genkwanines 6 和 rediocides 7; 其中, daphnetoxins 通常图 1 瑞香烷型二萜骨架 Figure 1 The skeleton of daphnane-type diterpenoids 也为羟基; rediocides 通常在 C3 和 C16 之间具有 12 个碳的大环内酯结构, 并且具有特殊的 C9、C12、C14 原酸酯结构而不是常见的 C9、C13、C14 原酸酯结构; 另外, 一些虎皮楠生物碱也具备瑞香烷骨架和断裂的瑞香烷骨架, 例如 8 和 9. 至今, 已经有 100 多个瑞香烷型二萜类天然产物得到分离、鉴定, 它们在抗 HIV、抗癌、抗白血病、亲神经性、杀虫、细胞毒性方面显示很好的生物活性 [2] .…”

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Synthetic Progress of Daphnane-type Diterpenoids

Liu¹,

Feng²,

Liu³

2016

Acta Chim. Sinica

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Daphnane diterpenoids usually embrace a 5/7/6-tricyclic ring system with poly-hydroxyl groups located at C3, C4, C5, C9, C13, C14, C20 and some special ones have a characteristic orthoester motif located at C9, C13, C14. The daphnane diterpenoids can be categorized into daphnetoxins, 12-hydroxydaphnetoxins, 1-alkyldaphnanes, resiniferonoids, genkwanines and rediocides, based on the oxygen containing functions at rings B and C, as well as the substitution pattern of the ring A. Besides, some daphniphyllum alkaloids are qualified with daphnane and seco-daphnane skeletons. Up to now, more than 100 daphnane diterpenoids have been isolated from Thymelaeaceae and Euphorbiaceae. Their structures have been determined on the basis of chemical correlation, NMR, X-ray diffraction, IR and other spectral analysis. The in-vitro and in-vivo experiments of these compounds have shown that they bear a wide range of biological activities including anti-HIV, anticancer, anti-leukemic, neurotrophic, pesticidal and cytotoxic effects. The biogenic hypothesis postulated that the daphnane-type and the tigliane type diterpenoids can be derived from a common intermediate, and that the tigliane-type can be transferred into the daphnane-type diterpenoids. There have been few papers on the total syntheses of daphnane diterpenoids owing to the synthetic challenges derived from their dense, highly oxygenated and polycyclic skeletons. However, numerous synthetic endeavors have been made in constructing core structures of daphnane diterpenoids based on various methodologies. In this paper, we focus on reviewing the synthetic efforts which have been made for daphnane diterpenoids, and we divide the main body of this paper into two parts, total syntheses and the related methodologies. The first part contains the asymmetric total synthesis of (＋)-resiniferatoxin, the gateway synthesis of C6-C7-epi-yuanhuapin, and the biomimetic synthesis of (±)-methyl-homosecodaphniphyllate. The second part is classified according to the sequence of constructing the ABC core of daphnane diterpenoids, including the [X-BC-ABC] approach, the [X-AB-ABC] approach, the [AX-ABC] approach, the [CX-ABC] approach, the [A'B'C'-ABC] approach and the [X-ABC] approach. Keywords daphnane; diterpenoid; (＋)-resiniferatoxin; total synthesis; synthetic methodology 1 引言瑞香烷型二萜类天然产物主要分布在瑞香科和大戟科植物中, 具有 5/7/6 三环骨架 1, 通常在 C3、C4、 C5、C9、C13、C14、C20 位置有羟基, 在 C9、C13、 C14 具有特定的原酸酯结构. 根据 B 环和 C 环的氧化形式以及 A 环的取代形式, 可将已知的瑞香烷型二萜天然产物(图 1)分为六类 [1] : daphnetoxins 2、12-hydroxydaphnetoxins 3、1-alkyldaphnanes 4、resiniferonoids 5、 genkwanines 6 和 rediocides 7; 其中, daphnetoxins 通常在 A 环具有 α-β 不饱和酮结构, 且 B 环具有 C5β 羟基、 C20 羟基、C6α-C7α 环氧结构; 12-hydroxydaphnetoxins 相对于 daphnetoxins 在 C12 处多一个含氧官能团 OR, 并且 OR 通常为酰氧基; 1-alkyldaphnanes 通常具有饱和的 A 环, 并且原酸酯烷基链末端和 A 环 C1 之间具有一个大环; resiniferonoids 相对于 daphnetoxins 而言, A 环具有 α-β 不饱和酮结构, B 环 C5 为亚甲基且 C6-C7 之间为双键, C20 为羟基或者酰氧基; genkwanines 通常在 B 环 C6-C7 之间具有双羟基, 并且饱和 A 环 C3 以及 B 环 C20

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Plant Orthoesters

Abstract: Chart 2. Structures of 1-Alkyldaphnanes (81-109), Resiniferonoids (110-113), Genkwanines (114-122), and Rediocides (123-129)

Cited by 176 publications

References 294 publications

Phragmalin-Type Limonoid Orthoesters from Chukrasia tabularis var. velutina

Phragmalin-Type Limonoid Orthoesters from Chukrasia tabularis var. velutina

Radical-Mediated Three-Component Reaction: A Study toward the Total Synthesis of Resiniferatoxin

Synthetic Progress of Daphnane-type Diterpenoids

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