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Search for "epoxidation" in Full Text gives 154 result(s) in Beilstein Journal of Organic Chemistry.
Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles
Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206
- intramolecular interaction between fluorine and metals would also facilitate the smooth progress of these reactions. Such high potential of 1a allowed us to apply it to nucleophilic epoxidation because the resultant epoxyester 2a is recognized as an intriguing building block (Scheme 1). Another expectation to 2a
- usefulness for the epoxidation of the β-CF3-α,β-unsaturated ketones [40], we applied this method at first for the epoxidation of 1b. However, contrary to our anticipation, only a total recovery of the substrate was observed, and further search for an oxidant reached the usage of a NaClO aqueous solution with
- (entries 3 vs 1 and 2). The drawback of this sequence was the isolated yield of 2b no more than 70% which was, at least in part, due to the production of the undesired hydrolyzed products from 1b and/or 2b under the alkaline conditions of this epoxidation reagent. This was experimentally proved by the
Hydrogen-bond activation enables aziridination of unactivated olefins with simple iminoiodinanes
Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197
- be unreactive towards sulfonamide (Scheme 4e), suggesting that epoxidation is not on path to the observed aziridines. For discussion of side-products and reaction mass balance, see Figure S4 (Supporting Information File 1). Based on these observations, we favor a mechanism in which H-bond activated
- give rise to epoxidation products. Epoxides are not on-path to the observed aziridines. f) Proposed reaction mechanism. Optimization of HFIP-promoted aziridination of cyclohexene (1a). Conditions: 0.20 mmol 1a, 0.40 mmol PhINTs 2a, 1.0 mL HFIP, N2 atmosphere, 20 °C, 16 h. Yield was determined via 1H
Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations
Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151
- aldehyde at the C6 sidechain. Furthermore, the fusion protein, JuvD-RhFRED, enabled regio- and diastereoselective epoxidation of the C12 double bond of macrocycles 80–82, culminating in the total synthesis of M-4365 A1 (83), M-4365 A3 (juvenimicin A4, 84), and M-4365 A2 (juvenimicin A3, 85), respectively
Computation-guided scaffold exploration of 2E,6E-1,10-trans/cis-eunicellanes
Beilstein J. Org. Chem. 2024, 20, 1320–1326, doi:10.3762/bjoc.20.115
- implies that protonation and cyclization may be concerted for that conformer (Figure S4, Supporting Information File 1). We previously transformed 2 into the trans,trans-6/6/6-tricyclic C6 alcohol 8 using mCPBA to epoxidize the C6–C7 alkene [7]. Under the same conditions, epoxidation of 1 yielded the 6,7
- with differing configurations at the ring-fused carbons and the 2,3-alkene. Protonation-mediated cyclization of trans- and cis-eunicellanes. (A) The 2E-trans- and 2E-cis-eunicellane skeletons form 6/6/6-tricyclic gersemiene skeletons in the presence of acid. Epoxidation of 1 with mCPBA yields the
Chemoenzymatic synthesis of macrocyclic peptides and polyketides via thioesterase-catalyzed macrocyclization
Beilstein J. Org. Chem. 2024, 20, 721–733, doi:10.3762/bjoc.20.66
- hydroxylation and epoxidation using three P450s (TylI, JuvD and MycCI) involved in the biosynthesis of several different macrolides, eight additional macrolides were achieved from 50, including juvenimicin B1, M-4365 G2, and juvenimicin A3. In the light of this approach, the following bioactive assay
- explored as prospective payloads for antibody-drug conjugation [81][82]. Numerous synthetic approaches have been devised to deliver the cryptophytes skeleton, indicating that the most challenging steps are the regio- and stereospecific macrocyclization and epoxidation [83]. To address these problems, in
- epoxidation with enzymatic macrocyclization in 2020 as shown in Scheme 8 [85]. According to their previous report [86], the production of fragments 61 was initiated by Evans’ asymmetric aldol and alcohol protection to generate 57. Six-step route transformations, including cross metathesis, afforded aldehyde
Production of non-natural 5-methylorsellinate-derived meroterpenoids in Aspergillus oryzae
Beilstein J. Org. Chem. 2024, 20, 638–644, doi:10.3762/bjoc.20.56
- -dependent monooxygenase InsA4. In this engineered pathway, FncE first synthesizes 5-MOA, which then undergoes farnesylation by FncB, methyl ester formation by InsA1, and epoxidation of the terminal olefin in the farnesyl moiety by InsA4 (Figure 2A). Thus, we heterologously expressed the genes encoding these
Recent developments in the engineered biosynthesis of fungal meroterpenoids
Beilstein J. Org. Chem. 2024, 20, 578–588, doi:10.3762/bjoc.20.50
- , FMO EsdpE, which epoxidizes the C-14, C-15 double bond of 13, was employed to produce 19, and the CYC EsdpB cyclizes in a chair–chair–chair conformation to form the 6-6-6 ring structure of 20 [18][19]. This difference in the epoxidation position represents a new point of biosynthetic diversity that
- hydroxy group terminates the cyclization [20][21]. In ascofuranone biosynthesis, compound 21 is initially hydroxylated at C-8, and then the hydroxylated product is cyclized via epoxidation by AscI to form the tetrahydrofuran ring of 23. The biosynthetic pathways of 22 and 23 were elucidated through
- molecular species withdraws a hydrogen atom, and the generated radical induces various reactions such as hydroxylation, unsaturation, epoxidation, halogenation, endoperoxidation, and C–C bond reconstruction, leading to the formation of diverse chemical structures [22][26][27][28][29][30][31]. Structure
Pseudallenes A and B, new sulfur-containing ovalicin sesquiterpenoid derivatives with antimicrobial activity from the deep-sea cold seep sediment-derived fungus Pseudallescheria boydii CS-793
Beilstein J. Org. Chem. 2024, 20, 470–478, doi:10.3762/bjoc.20.42
- II, which could be transferred to III by cyclization and epoxidation. Oxidation and methylation of intermediate III would produce IV. Compounds 1–4 could be obtained by nucleophilic attack at C-8 with the hydroxy or thiol group from IV via intermediate V, followed by oxidation and cyclization
Synthesis of ether lipids: natural compounds and analogues
Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96
- tosylation of the primary alcohol produced 4.8. The epoxidation of 4.8 occurred by reaction with t-BuOK in THF, thus producing 4.9 as a chiral electrophile. The regioselective opening of the epoxide is achieved by adding the octadecanol sodium salt. The intermediate was debenzylated by catalytic
- from allyl alcohol (Figure 7) [82]. The Sharpless asymmetric epoxidation of allyl alcohol followed by tosylation produced glycidyl tosylate 7.1a (Figure 7). The reaction of palmityl alcohol (C16H33-OH) in the presence of a catalytic amount of BF3 open regio- and stereoselectively the epoxide to produce
- either sn-1 and sn-2 positions or sn-2 and sn-3 positions [97]. The incorporation of one methylene unit is shown in Figure 13 as an illustration of all these possibilities. But-3-en-1-ol (13.1) was alkylated with bromohexadecane to produce the ether 13.2. The epoxidation of the carbon–carbon double bond
Asymmetric synthesis of a stereopentade fragment toward latrunculins
Beilstein J. Org. Chem. 2023, 19, 428–433, doi:10.3762/bjoc.19.32
- , in view of its coupling to 8. We first relied the chemoselective epoxidation of the homoallylic alcohol, done in presence of VO(OiPr)3 (20 mol %) and t-BuOOH to afford epoxide 13, in 86% yield and a dr of 75:25 (measured by NMR, presumably resulting from the major diastereoisomer of 13; minor isomers
- were not identified), when the reaction was performed at room temperature during 6 hours. This vanadium catalyst superseded VO(acac)2 in terms of yields [26][27]. Additional epoxidation attempts allowed to improve the dr to 82:18 (82% yield) when the reaction was left at −30 °C for 6 days
Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities
Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31
- acetic anhydride followed by epoxidation using m-CPBA gave protected epoxide 50. Subsequent removal of the acetate group using ammonia led to racemic compound 1 (Scheme 8). Rychnovsky and Hwang succeeded in the total syntheses of combretastatin D-2 (2) in a 36% overall yield after 13 steps and
- combretastatin D-1 (1) in 23% overall yield after 16 steps. Later, the same authors performed the enantioselective synthesis of 1 in an attempt to review its absolute configuration [41]. Thus, acetylation of compound 2 followed by the use of Jacobsen’s catalyst [42] to perform the epoxidation of the double bond
- group followed by protection of the obtained alcohol with benzyl bromide provided compound 55, which was subjected to an epoxidation using m-CPBA followed by ring opening using DIBAL [46]. The obtained alcohol was then protected with TBSCl to give fragment 57 (Scheme 10). Using similar conditions to
Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series
Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23
Germacrene B – a central intermediate in sesquiterpene biosynthesis
Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18
- Sharpless epoxidation of its derivative 15-hydroxygermacrene (17) showed that this material was racemic, indicating a rapid interconversion between the enantiomers of 17. Consequently, also the enantiomers of 1 may undergo a fast interconversion [52]. The 1H and 13C NMR data of 1 have been reported [26
- synthesis from β-eudesmol (30) through epoxidation to 31, dehydration to 32 and epoxide opening with LiAlH4 yielded (−)-11 (Scheme 9C) [77], contradicting this assignment. Notably, Šorm and co-workers noticed that 11 was racemic, because neither 11 nor any of its degradation products showed optical activity
Total synthesis of grayanane natural products
Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181
- the PMB protecting group, Dess–Martin oxidation, and SmI2-induced cyclization. This last step was highly selective, giving solely the intermediate 17. The synthesis was then pursued by the hydroboration–oxidation of the monosubstituted alkene, followed by stereoselective epoxidation of the 1,1
- group on C6 was introduced after cyclopropane ring-opening, ketone protection, epoxidation and reductive ring-opening of the resulting epoxide. A one-pot β-keto phosphonate formation/Horner–Wadsworth–Emmons reaction with formaldehyde afforded 38, a precursor for the key oxidative dearomatization-induced
- reagent and DMDO could induce an epoxidation on the strained olefin. From intermediate 40, the key reductive epoxide opening/Dowd–Beckwith rearrangement cascade could be performed in the presence of an in situ-generated Ti(III) catalyst. The main side-product of this reaction was due to a simple reductive
Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field
Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179
- addition to the electron-rich C=C bond [58] or proton loss followed by β-functionalization [59][60][61]. The iminium cation catalysis is used in the activation of electrophilic properties of enones for the nucleophilic epoxidation by hydroperoxides (Scheme 2B). N-Heterocyclic carbene (NHC) organocatalysis
- active oxidative agent. Asymmetric quaternary ammonium phase-transfer catalysts proved to be effective in the asymmetric nucleophilic epoxidation of electron-poor alkenes by hydroperoxides [70] and the asymmetric hydroxylation of enolizable carbonyl compounds employing O2 or H2O2 as terminal oxidants [71
- –H2O2 system the adducts of H2O2 and ketones (perhydrates) can also be active oxidative species [51]. Dioxiranes formed from ketones and hydroperoxides are electrophilic oxygen transferring agents used in epoxidation (including asymmetric variants) [131][132], CH-hydroxylation, and other oxidation
Cytochrome P450 monooxygenase-mediated tailoring of triterpenoids and steroids in plants
Beilstein J. Org. Chem. 2022, 18, 1289–1310, doi:10.3762/bjoc.18.135
- that performs hydroxylation and epoxidation reactions of the β-amyrin (6) scaffold to produce 12,13β-epoxy-16β-hydroxy-β-amyrin [1][99]. Thus, CYP51H10 is an example of a neofunctionalised CYP recruited from primary sterol metabolism. Two members of the CYP87D subfamily decorate the tetracyclic
Anti-inflammatory aromadendrane- and cadinane-type sesquiterpenoids from the South China Sea sponge Acanthella cavernosa
Beilstein J. Org. Chem. 2022, 18, 916–925, doi:10.3762/bjoc.18.91
- α-corocalene (O) [35]. An epoxidation at C-4/C-5 of O resulted in the formation of α-corocalene epoxide (P) [35], which was further hydrolyzed to generate the final product 7 [36]. In the anti-inflammatory assay, the transcriptional expression level of the representative inflammatory genes such as
The stereochemical course of 2-methylisoborneol biosynthesis
Beilstein J. Org. Chem. 2022, 18, 818–824, doi:10.3762/bjoc.18.82
- Sharpless epoxidation as a key step and purification of enantiomerically enriched intermediates through HPLC separation on a chiral stationary phase. Their enzymatic conversion with 2-methylisoborneol synthase (2MIBS) demonstrates that (R)-2-Me-LPP is the on-pathway intermediate, while a minor formation of
- comparison in these analyses. Conclusion Both enantiomers of 2-Me-LPP can be selectively prepared using a Sharpless epoxidation strategy in high enantiomeric purity of >75% ee. HPLC purification of the synthetic precursor 2-methyllinalool using a chiral stationary phase can make the pure enantiomers
Rapid gas–liquid reaction in flow. Continuous synthesis and production of cyclohexene oxide
Beilstein J. Org. Chem. 2022, 18, 660–668, doi:10.3762/bjoc.18.67
- Medical Science, Nijigaoka, Kani-city, Gifu Prefecture, 509-0293, Japan 10.3762/bjoc.18.67 Abstract The enhanced reaction rate in the epoxidation of cyclohexene with air as an oxidant was discovered without any added catalyst utilizing a continuous flow reactor constructed with readily available
- with good operational stability, evaluated by a constant high yield of cyclohexene oxide, to obtain the desired product with high productivity. Keywords: air; continuous flow; cyclohexene oxide; flow epoxidation; rapid gas–liquid reaction; Introduction From the past to the present, organic synthesis
- method for the production of cyclohexene oxide is highly desired to be developed, taking sustainability for the environment and our society into consideration. The general synthetic procedure for cyclohexene oxide is the epoxidation of cyclohexene [7][8]. Among various oxidizing agents used in the
Menadione: a platform and a target to valuable compounds synthesis
Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43
- nucleus, due to its greater reactivity when compared to the adjacent aromatic ring, which depends on previous modifications in the menadione intermediates [95]. Epoxidation reactions The use of menadione in the preparation of epoxides is widely reported in the scientific literature. In nature, menadione
- ]. The authors studied a broad range of quinone derivatives among which compound 39 was obtained through reaction of menadione (10) and hydroperoxide 38 in 71% yield and 45% ee (Scheme 11A). Analogously, Kosnik and co-workers described a similar epoxidation methodology using a series of pyranose-derived
- anomeric hydroperoxides (HPO) to obtain epoxides 40 with moderate ees (Scheme 11B) [100][101]. Bunge and co-workers used the enantiomerically pure dihydroperoxide 41 in the DBU-mediated epoxidation of menadione (10) for the enantioselective synthesis of epoxide 42 (92% yield and 45–66% ee) (Scheme 11C
Efficient and regioselective synthesis of dihydroxy-substituted 2-aminocyclooctane-1-carboxylic acid and its bicyclic derivatives
Beilstein J. Org. Chem. 2022, 18, 77–85, doi:10.3762/bjoc.18.7
- . Synthesis of cyclic β-amino acid 6. Epoxidation of Boc-protected amino ester 4 and hydrolysis of epoxide 7 with HCl(g)–MeOH. Reaction of epoxide 7 with NaHSO4 in methylene chloride/MeOH. Synthesis of cyclic β-amino acid derivative 8. Suggested mechanism for the reaction of epoxide 7 with NaHSO4. Supporting
Highly stereocontrolled total synthesis of racemic codonopsinol B through isoxazolidine-4,5-diol vinylation
Beilstein J. Org. Chem. 2021, 17, 2781–2786, doi:10.3762/bjoc.17.188
- -stereoselective epoxidation of 2,3-dihydroisoxazole with in situ-generated DMDO, the syn-selective α-chelation-controlled addition of vinyl-MgBr/CeCl3 to the isoxazolidine-4,5-diol intermediate, and the substrate-directed epoxidation of the terminal double bond of the corresponding γ-amino-α,β-diol with aqueous
- methodology based on the trans-stereoselective epoxidation reaction of 2,3-dihydroisoxazoles followed by the regioselective hydrolysis of the corresponding isoxazolidinyl epoxide [15][16]. Very recently, we have reported the synthesis of γ-(hydroxyamino)-α,β-diols by the addition of Grignard reagents to
- be prepared by substrate-directed epoxidation. A subsequent SN2 intramolecular epoxide ring-opening cyclization could provide an N-Cbz-protected pyrrolidine derivative with a hydroxymethyl group at C-5 and with trans configuration relative to the hydroxy group at C-4. Finally, (±)-codonopsinol B (1
Strategies for the synthesis of brevipolides
Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157
- commercially available (E)-p-methoxycinnamic acid (17). The vital intermediate 16 is expected from cyclopropyl epoxy alcohol 18, which in turn can be prepared from allylic alcohol 19 via the Furukawa-modified Simmons–Smith cyclopropanation and VO-mediated epoxidation. Acetylfuran (20) is chosen as the six
- isolated in 80% yield over two steps. Reduction of the ester provided allylic alcohol 29 (92%) ready for later epoxidation. After considerable optimizations, the authors found that the dropwise addition of TBHP to 29 in refluxing benzene solution containing a catalytic amount of VO(acac)2 afforded the
- . Eventually, trans-crotonaldehyde (62) is selected as the precursor for this study. The study began with the enantioselective epoxidation of trans-crotonaldehyde (62) under Jørgensen conditions using organocatalyst 63, followed by a two-carbon homologation to obtain α,β-unsaturated epoxy ester 64 in 78% yield
Asymmetric organocatalyzed synthesis of coumarin derivatives
Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128
- , tolerates electron-donating and -withdrawing groups and maintains its performance in gram scale (Scheme 36). Page et al. developed a total synthesis of the natural product (+)-scuteflorin A (119), being the key step an asymmetric epoxidation of xanthyletin (115) employing biphenylazepinium 120 as PTC
- together with tetraphenylphosphonium monoperoxysulfate (TPPP) as the stoichiometric oxidant [76]. The authors mentioned that this epoxidation had been previously reported using Jacoben’s (S,S)-(+)-salen-Mn(III) catalyst with 78–83% yield and 95% ee, and via organocatalysis they obtained 98% yield and ≥99
Double-headed nucleosides: Synthesis and applications
Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98
- . The convergent synthesis of the double-headed nucleosides was achieved from uridine, which was first converted to the 3′,5′-(1,1,3,3-tetraisopropyldisiloxan-1,3-diyl)-protected (TIPDS) ketonucleoside 1 following a standard procedure [40]. The subsequent Corey–Chaykovsky epoxidation [41] of 2
- following the literature procedure [14][62]. The epoxide 109 so formed was reacted with thymine to afford nucleoside 107, which on pixylation and removal of the tert-butyldimethylsilyl-protecting group in the presence of TBAF give double-headed nucleoside 110 (Scheme 25) [30][31][65]. The epoxidation of the
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