Stability trends in carbocation intermediates stemming from germacrene A and hedycaryol

• Naziha Tarannam,
• Prashant Kumar Gupta,
• Shani Zev and
• Dan Thomas Major

Beilstein J. Org. Chem. 2024, 20, 1189–1197, doi:10.3762/bjoc.20.101

• monoterpenes (C10), sesquiterpenes (C15), and diterpenes (C20). Enzymes such as monoterpene, sesquiterpene, and diterpene synthases act on geranyl diphosphate (GPP), farnesyl diphosphate (FPP), and geranylgeranyl diphosphate (GGPP) to yield mono-, sesqui-, and diterpenes, respectively. These linear precursors

• microbes, in the form of alcohols, ketones, lactones, and glycosides, and of these various forms, the oxo derivatives in particular have strong aroma and biological activity. Interestingly, in addition to being used routinely as flavorings and aromatic agents, sesquiterpene oxo derivatives also have

• anticancer, antimalarial, antibacterial, and antiviral activity [8][9]. For instance, the well-known artemisinin family of drugs, which is currently the first line of treatment against malaria, is a sesquiterpene lactone [10]. Sesquiterpenes produced by plants [10] also have plant growth regulating and

Enhancing structural diversity of terpenoids by multisubstrate terpene synthases

• Min Li and
• Hui Tao

Beilstein J. Org. Chem. 2024, 20, 959–972, doi:10.3762/bjoc.20.86

• provide updated examples on this topic. Recently, novel sesquiterpene backbones 41–44 were synthesized by feeding presilphiperfolan-8β-ol synthase (BcBOT2) with methyl-shifted FPP analogs 45–47 (Figure 4a) [43]. Three new homosesquiterpenes 48–50 were produced after the biotransformation of BcBOT2 with

Discovery and biosynthesis of bacterial drimane-type sesquiterpenoids from Streptomyces clavuligerus

• Dongxu Zhang,
• Wenyu Du,
• Xingming Pan,
• Xiaoxu Lin,
• Fang-Ru Li,
• Qingling Wang,
• Qian Yang,
• Hui-Min Xu and
• Liao-Bin Dong

Beilstein J. Org. Chem. 2024, 20, 815–822, doi:10.3762/bjoc.20.73

• SsDMS, including a conserved “DXDD” motif, indicating its potential as a class II sesquiterpene synthase (Figure S8, Supporting Information File 1) [20]. Further analysis of adjacent genes revealed a Nudix hydrolase located upstream of the putative DMS, similar to the reported situation with SsDMS [19

Functions of enzyme domains in 2-methylisoborneol biosynthesis and enzymatic synthesis of non-natural analogs

• Binbin Gu,
• Lin-Fu Liang and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1452–1459, doi:10.3762/bjoc.19.104

• unpleasant off-flavour [19][20]. The biosynthesis of 1 has been extensively studied. The initial hypothesis that 1 could be a degraded sesquiterpene [3] was not confirmed through isotopic labelling experiments that rather pointed to a methylated monoterpene [10][21]. Based on these experiments a biosynthetic

Functional characterisation of twelve terpene synthases from actinobacteria

• Anuj K. Chhalodia,
• Houchao Xu,
• Georges B. Tabekoueng,
• Binbin Gu,
• Kizerbo A. Taizoumbe,
• Lukas Lauterbach and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1386–1398, doi:10.3762/bjoc.19.100

• identified by GC–MS. The characterised enzymes include a new epi-isozizaene synthase with monoterpene synthase side activity, a 7-epi-α-eudesmol synthase that also produces hedycaryol and germacrene A, and four more sesquiterpene synthases that produce mixtures of hedycaryol and germacrene A. Three

• have been reported. Here, we report on the discovery and functional characterisation of four sesquiterpene synthases from actinomycetes with novel functions, in addition to several actinomycete terpene synthases for which functional homologs have been identified before. Results and Discussion

• ), geranylgeranyl pyrophosphate (GGPP) and geranylfarnesyl pyrophosphate (GFPP). Sesquiterpene synthases The enzyme from K. kofuensis (Table 1, entry 1) exhibited all highly conserved motifs required for functionality including the aspartate-rich motif (83DDAYCD) and the NSE triad (223NDIASYYKE, Figure S2

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

Five new sesquiterpenoids from agarwood of Aquilaria sinensis

• Hong Zhou,
• Xu-Yang Li,
• Hong-Bin Fang,
• He-Zhong Jiang and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 998–1007, doi:10.3762/bjoc.19.75

• inhibition [8], anti-inflammatory [10], antiasthmatic [11], antidiabetic [12], and antioxidant [13] activities, have been reported for agarwood extracts [14][15]. Our group recently reported five structurally intriguing and biologically active sesquiterpene dimers [16], which attracted our interest to gain

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• successfully treated by artemisinin combination therapy (ACT). Artemisinin can be isolated from the Artemisia annua (sweet wormwood) plant. This sesquiterpene lactone bearing a peroxide is a prodrug of the biologically active dihydroartemisinin. In 2012, Zhu and Cook developed a gram-scale asymmetric total

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• note, this compound entails the oxabicyclo[4.2.1]nonane core present in schindilactone A (68). The synthesis of schindilactone A (68) was achieved in 29 steps (0.11% overall yield). 1.1.2.2 Late-stage introduction of cyclooctene: The marine sesquiterpene dactylol (72), isolated from both sea hare

• sesquiterpene with a unique framework. Indeed, this natural compound has a rare [6.3.0] carbocyclic backbone with a bridging butyrolactone, and possesses five cis stereocenters [39][40]. This compound, in a racemic version, has been studied by Krafft, Cheung and Abboud (Scheme 13) [39]. The initial strategy

• access to exo-methylene [38][55]. This concept was exemplified with the synthesis of poitediol (118) (Scheme 21), a bicyclopentacyclooctane compound isolated from the red seaweed Laurencia poitei in 1978. This sesquiterpene bearing a [5-8] bicyclic structure includes an exo-methylidene moiety on the

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• initial formation from farnesyl diphosphate, these neutral intermediates can become reprotonated for a second cyclisation to reach the bicyclic eudesmane and guaiane skeletons. This review summarises the accumulated knowledge on eudesmane and guaiane sesquiterpene hydrocarbons and alcohols that

• potentially arise from the achiral sesquiterpene hydrocarbon germacrene B. Not only compounds isolated from natural sources, but also synthetic compounds are dicussed, with the aim to give a rationale for the structural assignment for each compound. A total number of 64 compounds is presented, with 131 cited

• ], Solidago canadensis [60], Citrus nobilis ((+)-form) [61], Zingiber officinalis [62], Myrica pensylvanica and M. macfarlanei [63], Trichogonia scottmorii [64], and Podocarpus spicatus in which case a high optical rotation was reported ([α]D20 = +82, c 2.9, CHCl3) [65]. The sesquiterpene 9 is a side product

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• sesquiterpene A, including spectral analysis and synthesis to determine its constitution and absolute configuration. Results and Discussion High-resolution mass spectrometry (HRMS) revealed both compounds A and C to be likely sesquiterpenes because of their molecular formula of C15H26O (m/z 222.1977, calcd for

• absolute configuration of the sesquiterpene A was elucidated by enantioselective gas chromatography. The enantiomers of the alcohols could be separated on a Hydrodex β-6TBDM phase (Figure 5). This allowed to determine the absolute configuration of the sesquiterpene A. A coinjection of a gland extract with

• identified in gular glands of male Hyperolius cinnamomeoventris. Total ion chromatogram (TIC) of a gular gland extract of Hyperolius cinnamomeoventris on a polar DB-wax GC phase. A, C: sesquiterpenes; B: cinnamomeoventrolide; D: (Z)-tetradec-5-en-13-olide; E: frogolide. Mass spectrum of sesquiterpene A (I

Vicinal ketoesters – key intermediates in the total synthesis of natural products

• Marc Paul Beller and
• Ulrich Koert

Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129

• ). (−)-Jiadifenoxolane A The Illicium sesquiterpenes containing a seco-prezizaane carbon framework are highly oxidized, structurally complex natural products. Maimone et al. published a remarkable synthesis of the Illicium sesquiterpene (−)-jiadifenoxolane A (36), starting from the abundant sesquiterpene (+)-cedrol (31

• with α-ketoester 81 furnished compound 82 with the last ring of the target (+)-gracilamine (83), which was accessible after two further steps. (−)-Irofulven Irofulven (87) is a highly cytotoxic, semisynthetic drug obtained from the illudin sesquiterpene family. In a de novo synthesis towards

Anti-inflammatory aromadendrane- and cadinane-type sesquiterpenoids from the South China Sea sponge Acanthella cavernosa

• Shou-Mao Shen,
• Qing Yang,
• Yi Zang,
• Jia Li,
• Xueting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 916–925, doi:10.3762/bjoc.18.91

• at C-7 and C-10 to give a pair of dihydroxy epimers 4 and 5. Compound 6 could be generated by the dehydration of 4/5 or by the multiple-step oxidation of M. Similarly, the plausible biosynthetic pathway of compound 7 could be proposed below. Multiple-step oxidation of N gave a phenolic sesquiterpene

• sesquiterpenoids not only extended the members of the sesquiterpenoid family but also enriched the chemical diversity of the Acanthella sponges. The plausible biosynthetic pathway of isolated compounds 1–7 was also proposed. Up to date, no sesquiterpene cyclase has been characterized for aromadendrane and

The stereochemical course of 2-methylisoborneol biosynthesis

• Binbin Gu,
• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 818–824, doi:10.3762/bjoc.18.82

• suggested to proceed through degradation of a sesquiterpene [2], but first feeding experiments with 14C-labeled acetate and methionine pointed to a methylated monoterpene [22]. Further investigations by feeding of 13C-labeled methionine and deuterated mevalonolactone isotopomers to Nannocystis exedens

Terpenoids from Glechoma hederacea var. longituba and their biological activities

• Dong Hyun Kim,
• Song Lim Ham,
• Zahra Khan,
• Sun Yeou Kim,
• Sang Un Choi,
• Chung Sub Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2022, 18, 555–566, doi:10.3762/bjoc.18.58

• . longituba (common name: ground ivy) has been used for the treatment of asthma, bronchitis, cholelithiasis, colds, and inflammation. In the present study, three new sesquiterpene glycosides (1–3), two new diterpene glycosides (4 and 5), and four known compounds (6–9) were isolated from its MeOH extract. A

• distributed in Korea, Japan, and China. This plant has been used as Korean traditional medicine for treating asthma, bronchitis, cholelithiasis, colds, and inflammation [1][2]. Previous studies have shown that G. hederacea var. longituba contains phytochemicals such as monoterpenoids, sesquiterpene lactones

• against SK-MEL-2 cell line, with an IC50 value of 9.81 μM. Conclusion Nine terpene derivatives, including three new sesquiterpene glycosides (1–3), two new diterpene glycosides (4 and 5), a known diterpene (6), and three known triterpenes (7–9) were isolated from CHCl3-, EtOAc-, and n-BuOH-soluble layers

Sesquiterpenes from the soil-derived fungus Trichoderma citrinoviride PSU-SPSF346

• Wiriya Yaosanit,
• Vatcharin Rukachaisirikul,
• Souwalak Phongpaichit,
• Sita Preedanon and
• Jariya Sakayaroj

Beilstein J. Org. Chem. 2022, 18, 479–485, doi:10.3762/bjoc.18.50

• . Compound 2 possesses a rare bicyclic sesquiterpene skeleton. The antimicrobial and cytotoxic activities of the isolated compounds were evaluated. Keywords: antimicrobial activity; cytotoxic activity; γ-lactone; soil-derived fungus; sesquiterpene; Trichoderma citrinoviride; Introduction The fungus

• configurations at C-5, C-6, C-7, and C-10 of compound 2 were proposed to be 5S, 6S, 7S, and 10R identical to those of the co-metabolites 4 and 5. The absolute configuration at C-4 was thus assigned to be R. Therefore, compound 2 is a rare bicyclic sesquiterpene. The isolated compounds 1 and 3–6 with sufficient

• rare bicyclic sesquiterpene. Unfortunately, none of the tested compounds 1 and 3–6 displayed antimicrobial and cytotoxic activities. Experimental General experimental procedures Infrared (IR) spectra were recorded with a Perkin-Elmer spectrum BX FTIR spectrometer. Ultraviolet (UV) spectra were obtained

A resorcin[4]arene hexameric capsule as a supramolecular catalyst in elimination and isomerization reactions

• Tommaso Lorenzetto,
• Fabrizio Fabris and
• Alessandro Scarso

Beilstein J. Org. Chem. 2022, 18, 337–349, doi:10.3762/bjoc.18.38

• synthesis of sesquiterpene natural product derivatives [38][39] and the carbonyl olefin metathesis leading to 2,5-dihydropyrroles [40]. Herein we present our investigation on the ability of the hexameric capsule 16 to act as a supramolecular self-assembled organocatalyst for a series of unimolecular

The enzyme mechanism of patchoulol synthase

• Houchao Xu,
• Bernd Goldfuss,
• Gregor Schnakenburg and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 13–24, doi:10.3762/bjoc.18.2

• sesquiterpene (2-2H)-16 that may take up the deuteron released in the formation of 5 (and similar compounds) to give (2,15-2H2)-H (Scheme 3C). Notably, none of the proposed mechanisms in Schemes 1–3 can explain the reported results from all labelling experiments and some of the reported findings are even

• three Me groups, four olefinic carbons (two quarternary, one CH and one CH2), and a tertiary alcohol, suggesting the structure of an oxidised (dehydrogenated) bicyclic sesquiterpene alcohol (Figure 4). The 1H,1H-COSY spectrum revealed one large contiguous spin system C-2-3-4(15)-5-6-7-8-9. HMBC

• terpene biosynthesis through neutral intermediates, and more specifically another example of sesquiterpene biosynthesis through the widespread biosynthetic intermediate germacrene A [11]. Initially assigned structures for patchoulol by Treibs (1) and by Büchi (2). Structures of patchoulol (3) and side

Targeting active site residues and structural anchoring positions in terpene synthases

• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 2441–2449, doi:10.3762/bjoc.17.161

• isopentenyl diphosphate (IPP), that can be fused by oligoprenyl diphosphate synthases to yield geranyl diphosphate (GPP, C10) as the precursor to monoterpenes, farnesyl diphosphate (FPP, C15) as sesquiterpene precursor, geranylgeranyl diphosphate (GGPP, C20) towards diterpenes, and geranylfarnesyl diphosphate

• (ΣVvdW) of the active site residues of TPSs can be easily calculated using a simple equation by Abraham and co-workers [18]. They show a clear trend, with the average values being largest for monoterpene synthases (MTPSs, ΣVvdW = 907 ± 24 Å3), and then decreasing for sesquiterpene synthases (STPSs, ΣVvdW

Volatile emission and biosynthesis in endophytic fungi colonizing black poplar leaves

• Christin Walther,
• Pamela Baumann,
• Katrin Luck,
• Beate Rothe,
• Peter H. W. Biedermann,
• Jonathan Gershenzon,
• Tobias G. Köllner and
• Sybille B. Unsicker

Beilstein J. Org. Chem. 2021, 17, 1698–1711, doi:10.3762/bjoc.17.118

• endophyte, a species of Cladosporium, we isolated and characterized two sesquiterpene synthases that can produce a number of mono- and sesquiterpenes like (E)-β-ocimene and (E)-β-caryophyllene, compounds that are dominant components of the herbivore-induced volatile bouquet of black poplar trees. As several

• of the fungus-derived volatiles like 2-phenylethanol, 3-methyl-1-butanol and the sesquiterpene (E)-β-caryophyllene, are known to play a role in direct and indirect plant defense, the emission of volatiles from endophytic microbial species should be considered in future studies investigating tree

• volatiles, some terpenoids are known to attract natural enemies of insect herbivores [2][12][13] or attract insects as shown for the sesquiterpene (E)-β-caryophyllene (1) [14][15]. Another sesquiterpene, (E)-β-farnesene (2), an aphid alarm pheromone, is also produced by plant species like Arabidopsis

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• further used in the work published in 2020 by Bisai et al. for the addition of 4-tolylboronic acid to 3-methyl-2-cyclohexenone in the total synthesis of the aromatic sesquiterpene (−)-ar-tenuifolene (Scheme 16) [12]. Later in 2020, Bisai et al. published the application of the L9/Pd(TFA)2 catalytic system

3-Acetoxy-fatty acid isoprenyl esters from androconia of the ithomiine butterfly Ithomia salapia

• Florian Mann,
• Daiane Szczerbowski,
• Lisa de Silva,
• Melanie McClure,
• Marianne Elias and
• Stefan Schulz

Beilstein J. Org. Chem. 2020, 16, 2776–2787, doi:10.3762/bjoc.16.228

• contained ithomiolide A (3), a pyrrolizidine alkaloid derived γ-lactone, I. s. derasa carried the sesquiterpene α-elemol (8) in the androconia. These differences might be important for the reproductive isolation of the two subspecies, in line with previously reported low gene exchange between the two

• contained small amounts of ithomiolide A (3), whereas PA derivatives were entirely absent in I. s. derasa. In contrast, the sesquiterpene α-elemol (8) was exclusively present in all tested individuals of I. s. derasa, together with some related minor sesquiterpenes. This sesquiterpene alcohol is likely

• formed from hedycaryol (7) during GC/MS analysis by a Cope-rearrangement [20][21], indicating that 7 might be originally present in the hairpencils. That said, we cannot disprove that this rearrangement could also occur in the androconia. Hedycaryol is an early product of sesquiterpene biosynthesis

Bifurcated synthesis of methylene-lactone- and methylene-lactam-fused spirolactams via electrophilic amide allylation of γ-phenylthio-functionalized γ-lactams

• Tetsuya Sengoku,
• Koki Makino,
• Ayumi Iijima,
• Toshiyasu Inuzuka and
• Hidemi Yoda

Beilstein J. Org. Chem. 2020, 16, 2769–2775, doi:10.3762/bjoc.16.227

• -butyrolactone; spirolactams; Introduction α-Methylene-γ-butyrolactone is a pharmaceutically important motif which is found in a wide variety of bioactive molecules including natural products (Scheme 1a) [1][2][3]. For example, sesquiterpene lactones represented by parthenolide and helenalin have attracted

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• ], a bicyclic sesquiterpene that belongs to the cuparene family isolated from Thuja orientalis [76]. More specifically, the authors designed a simple route to enone 67, a key intermediate in several previous total syntheses [77][78]. Its synthesis was achieved in two steps, namely a nickel-catalyzed

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• double displacement with sodium sulfide to obtain thietane-3,3-diyldimethanol (13), which was further converted into two different thietanose nucleosides 2 and 14 [33] (Scheme 2). In the synthesis of sesquiterpene thioalkaloids, the method also was utilized. A double-aldol condensation of methyl

• intermediate for the total synthesis of sesquiterpene thioalkaloids (Scheme 3). Spiro[3.3]heptane derivatives were recently used as the surrogates of piperazines, piperidines, morpholines, and thiomorpholines, which display pharmacological activities [35]. 1,6-Thiazaspiro[3.3]heptane (24) was synthesized for

• sesquiterpene thioalkaloids 58 and 59 [43] (Scheme 13). 2.2. Synthesis via intramolecular nucleophilic displacements 2.2.1 Synthesis via the direct cyclic thioetherification of γ-mercaptoalkanols: The direct cyclic thioetherification of γ-mercaptoalkanols was regarded as an efficient route to synthesize