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Search for "oxidation" in Full Text gives 1278 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Auxiliary strategy for the general and practical synthesis of diaryliodonium(III) salts with diverse organocarboxylate counterions
Beilstein J. Org. Chem. 2024, 20, 1020–1028, doi:10.3762/bjoc.20.90
- reported [18][19] (Scheme 1). The importance of the trimethoxyphenyl (TMP) group as an auxiliary (dummy) ligand on the iodonium salt has prompted researchers to synthesize aryl(TMP)iodonium(III) trifluoroacetates via oxidation of iodoarene with m-chloroperbenzoic acid (mCPBA) in the presence of
- prepared through the oxidation of iodoarenes with NaBO3·4H2O [34], AcOOH [35], mCPBA [36], and NaClO·5H2O [37] in the presence of acetic acid. The reaction of (diacetoxyiodo)arenes bearing electron-donating (methyl (1b), methoxy (1c), and phenyl (1d)) and electron-withdrawing (methyl ester (1e), nitro (1f
- ) carboxylate 7aj carrying a fluorescent-labeling group in 93% yield. Iodosoarenes 5b–f can be easily obtained by treating (dichloroiodo)arenes [41] or (diacetoxyiodo)arenes [42] with sodium hydroxide, by oxidation of iodoarenes with NaClO·5H2O [43], or by electrolysis [44]. The reaction scope of iodosoarenes
Carbonylative synthesis and functionalization of indoles
Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87
- by the oxidation of the catalyst. The reaction proceeded with dppp and 1,10-phenantroline (12 mol % each) under 6 bar of CO at 80 °C in DMF for 22–96 hours depending on the substrate. After the required reaction time, seven carbazolones were isolated with good yields of up to 89% (Scheme 12). In 2005
- reactions were catalyzed through Pd(dba)2, dppp, 1,10-phenantroline under 6 bar of CO at 120 °C in DMF and the products were obtained within 48–96 hours. All products were isolated with good yields except the pyranindole because it decomposed; it could only be isolated after complete oxidation in air. The
Enhancing structural diversity of terpenoids by multisubstrate terpene synthases
Beilstein J. Org. Chem. 2024, 20, 959–972, doi:10.3762/bjoc.20.86
- at low titers [61]. To increase C16 terpene titers, a later study redirected the 3-ketovaleryl-CoA formation step from the previous thiolase-dependent LMVA pathway to a β-oxidation LMVA pathway, and combined it with a promiscuous phosphatase, NudB, to produce C6- and C7-isoprenol. Notably, the final
Innovative synthesis of drug-like molecules using tetrazole as core building blocks
Beilstein J. Org. Chem. 2024, 20, 950–958, doi:10.3762/bjoc.20.85
- of tetrazole building blocks which provides the handle of alcohol functionality and further oxidation serves as an oxo component in subsequent MCRs (Figure 1d). The synthesis of oxo-tetrazoles was targeted because of the prevalence of the aldehyde substrate in MCRs and their use in medicinal
- chemistry literature. Results and Discussion First, we planned to provide a number of orthogonally protected tetrazole carbaldehyde building blocks. This should be accomplished by synthesizing the hydroxymethyl precursors by a Passerini-tetrazole synthesis, followed by oxidation to the aldehyde (Figure 1d
- Passerini-tetrazole product. Then, the Swern oxidation [22][23][24], which is widely exploited and has a wide tolerance of functional groups, was used to convert the tetrazole containing alcohols to aldehydes, in particular for derivatives bearing convertible isocyanides. Most building blocks were well
Enantioselective synthesis of β-aryl-γ-lactam derivatives via Heck–Matsuda desymmetrization of N-protected 2,5-dihydro-1H-pyrroles
Beilstein J. Org. Chem. 2024, 20, 940–949, doi:10.3762/bjoc.20.84
- followed by a sequential Jones oxidation. The overall method displays a broad scope and good enantioselectivity, favoring the (R) enantiomer. The applicability of the protocol is highlighted by the efficient enantioselective syntheses of the selective phosphodiesterase-4-inhibitor rolipram and the
- Heck adducts (methyl N,O-acetals) were efficiently converted into several arylated γ-lactams by a simple oxidation procedure (Jones oxidation). To demonstrate the applicability of the strategy, two of the chiral aryl-lactams were further derivatized to provide the selective phosphodiesterase-4
- presence of a methoxy group after the Heck–Matsuda reaction indicates methanolysis after arylation. Given the importance of the lactam rings, we envisioned a sequential Jones oxidation protocol without isolation of the methyl N,O-acetal products to obtain the corresponding lactams 4. As observed in
(Bio)isosteres of ortho- and meta-substituted benzenes
Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78
- , deiodination at the bridgehead position, and nucleophilic substitution at the alkyl chloride. From 1,2-BCP (±)-4, a variety of 1,2-BCPs were prepared through basic chemical transformations (Scheme 1B) [26]. Selective deprotection gave access to free alcohol-containing 1,2-BCPs (±)-5 and (±)-8. Oxidation and
- esterification of alcohol (±)-5 gave redox active ester (±)-6, which was itself shown to be a suitable substrate for nickel-catalysed decarboxylative cross coupling reactions to aryl-substituted BCPs (±)-7. Oxidation of alcohol (±)-8 gave acid (±)-9 which yielded amine (±)-10 after a Curtius rearrangement
- -workers also reported the modification of these 1,2-BCHs to increase the number of derivatives accessible using this approach (Scheme 3B) [38]. Transformation of the naphthyl ketone moiety of BCH (±)-25d by Baeyer–Villiger oxidation followed by hydrolysis gave carboxylic acid (±)-26. Through Curtius
Confirmation of the stereochemistry of spiroviolene
Beilstein J. Org. Chem. 2024, 20, 852–858, doi:10.3762/bjoc.20.77
- Abstract We confirm the previously revised stereochemistry of spiroviolene by X-ray crystallographically characterizing a hydrazone derivative of 9-oxospiroviolane, which is synthesized by hydroboration/oxidation of spiroviolene followed by oxidation of the resultant hydroxy group. An unexpected thermal
- boron migration occurred during the hydroboration process of spiroviolene that resulted in the production of a mixture of 1α-hydroxyspiroviolane, 9α- and 9β-hydroxyspiroviolane after oxidation. The assertion of the cis-orientation of the 19- and 20-methyl groups provided further support for the revised
- hydroxy group, or a keto group) for further derivatization. Spiroviolene was not transformed when subjected to conditions for allylic oxidation (SeO2) even at elevated temperature [27], and the starting material was fully recovered. We have also tried hydroboration/oxidation conditions for transforming
Skeletal rearrangement of 6,8-dioxabicyclo[3.2.1]octan-4-ols promoted by thionyl chloride or Appel conditions
Beilstein J. Org. Chem. 2024, 20, 823–829, doi:10.3762/bjoc.20.74
- small amounts of the C2 epimers. Oxidation of the hemiacetal 12a gave a moderate and unoptimised yield of 40% for lactone 24. The probable mechanism for the transformation with SOCl2 and under Appel conditions is shown in Figure 2. The reaction of alcohol 10 with the electrophiles gives the
Discovery and biosynthesis of bacterial drimane-type sesquiterpenoids from Streptomyces clavuligerus
Beilstein J. Org. Chem. 2024, 20, 815–822, doi:10.3762/bjoc.20.73
- a precursor for derivatives 2–4. The biosynthetic pathway is likely to involve enzymatic modifications at the C-2 and C-3 positions, leading to the formation of diols 2 and 3, with additional oxidation steps producing ketone 4 (Figure 3b). This supports the presence of three P450s in the cav cluster
Advancements in hydrochlorination of alkenes
Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72
- oxidation, whereas in Nicewicz's report, the alkene is oxidized. This modification allows for a significantly larger reaction scope (Scheme 29). Terminal alkenes and several functional groups such as ethers (163), esters (165), ketones (166), nitriles (167), and enones (170) are tolerated. The
- following mechanism (Scheme 30B): Initially, the terminal palladium species H, formed through the hydropalladation of terminal or internal alkenes (upon chain walking), coordinates to NCS via hydrogen bonding (I). Subsequent oxidation takes place to yield a Pd(IV) species (J), which then undergoes reductive
Research progress on the pharmacological activity, biosynthetic pathways, and biosynthesis of crocins
Beilstein J. Org. Chem. 2024, 20, 741–752, doi:10.3762/bjoc.20.68
- ), or zeaxanthin (7) by a carotenoid cleavage dioxygenase (CCD) to form crocetin aldehyde (8) and, after oxidation, 1, and 3) glycosylation of 1 to generate crocins (Figure 3). Since the biosynthetic pathways of 5 in plants and microorganisms have been elucidated and reviewed, we will only elaborate the
- duplication events during genome evolution [96]. When expressed in the callus of Nicotiana tabacum, GjCCD4a exhibited a higher efficiency in carotenoid cleavage than CsCCD4a [85]. ALDHs: ALDH utilizes NAD+ or NADP+ as cofactor to catalyze the oxidation of acetaldehyde into carboxylic acids. In 2018, Demurtas
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
- overall yield. According to the biosynthetic approach, these macrolides are produced by the type I PKS system, including thioesterase (TE)-catalyzed cyclization of the linear hexa- and heptaketide intermediates, post-PKS oxidation, and glycosylation [67]. Cane and co-workers reported that Pik TE, the TE
- then transformed into aldehyde 31 through several protecting group adjustments and the corresponding alcohol and Ley oxidation. After the preparation of 33 using Evans syn-aldol condensation as a critical step, 34 was produced by thioester formation, desilylation, and allylic oxidation. Incubating 34
- macrolactones. Using engineered variants of S. venezuelae ATCC 15439 designated strains DHS200141 [71] and YJ11242 [72], 24 and 25 were transformed to the corresponding macrolides through whole cell biotransformation to append ᴅ-desosamine and perform C–H oxidation(s) by the PikC monooxygenase (Scheme 6b). In
Genome mining of labdane-related diterpenoids: Discovery of the two-enzyme pathway leading to (−)-sandaracopimaradiene in the fungus Arthrinium sacchari
Beilstein J. Org. Chem. 2024, 20, 714–720, doi:10.3762/bjoc.20.65
- and absolute configuration of 1, we assumed this compound could be a biosynthetic precursor of myrocins. In the flanking regions of AsPS and AsCPS, genes encoding oxidoreductases such as cytochrome P450 are present. These genes might be involved in the oxidation of 1 in the biosynthesis of myrocins. A
SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes
Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64
- , further oxidation would generate the corresponding carbocation, which upon reaction with a nucleophilic alkyne would form the product (Scheme 1B, reaction 3). Based on precedence in the literature, this method should allow to transfer efficiently both aryl- and alkyl-substituted alkynes [41][42][43][44
- ]. On the other hand, the nature of the alkene might be limited as it would strongly influence the oxidation potential of the carbon radical and the stability of the resulting carbocation. Recently, we reported the first successful application of an RPC strategy for the azido-alkynylation of styrenes
- since it is known to be reduced by photocatalysts such as Cu(dap)2Cl [17]. This perfectly fits a catalytic cycle involving the reduction of Ts-ABZ (3) followed by oxidation of the carbon radical to form a carbocation and regenerate the ground state catalyst. Styrene (1a) was used as model substrate
Regioselective quinazoline C2 modifications through the azide–tetrazole tautomeric equilibrium
Beilstein J. Org. Chem. 2024, 20, 675–683, doi:10.3762/bjoc.20.61
- were oxidized to the corresponding sulfonylquinazolines 8. Inspired by our previous work [19] a TFAA/H2O2 oxidizing system was tried first but yielded several side-products, such as the hydrolysis product and unwanted oxidation of the quinazoline N3 position. Changing the oxidant to mCPBA (with 96
- % purity) [26] provided a more selective reaction, no water-based work-up was needed and the pure product was obtained by simple recrystallization from ethanol in yields up to 88%. The oxidation step thiol → sulfoxide was fast and full conversion to the intermediate was achieved in one hour for most
- , thioether substituents were installed in the presence of K2CO3. For alkylthiols, DMF was used, but arylthiols required milder conditions with MeOH and cooling to acquire regioselectivity to the C4 position which resulted in yields up to 91%. Oxidation with purified mCPBA (commercial mCPBA with 68% purity
Recent developments in the engineered biosynthesis of fungal meroterpenoids
Beilstein J. Org. Chem. 2024, 20, 578–588, doi:10.3762/bjoc.20.50
- reactions with several substrates illustrate the broad substrate specificity of SptF. To apply the high potential of SptF to generate a variety of oxidation products, meroterpenoids (39, 41, 42, 45, and 46) and terpenoids (49 and 52) were also used as unnatural substrates to construct a series of new
- change their reaction products depending on the conformation of the terpenoid skeleton, the regiospecificity of the oxidation reaction can be modified by introducing random mutations in the substrate-binding site of αKG-dependent dioxygenase. The αKG-dependent dioxygenase AndA withdraws H-12 of
Synthesis and biological profile of 2,3-dihydro[1,3]thiazolo[4,5-b]pyridines, a novel class of acyl-ACP thioesterase inhibitors
Beilstein J. Org. Chem. 2024, 20, 540–551, doi:10.3762/bjoc.20.46
- to afford thiazolopyridines 12a–c in good yield. This allowed us to circumvent the previously employed alkylation–oxidation–reduction sequences (Scheme 2) [12]. Thereupon, we recognized that we could introduce two halogen atoms in the halogenation step and carry one through to the end of the
Switchable molecular tweezers: design and applications
Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45
- achieved by chemical (hydroxide/proton) or electrochemical (reduction/oxidation) stimuli allowing the enrichment of perylene from a mixture of polycyclic aromatic hydrocarbons (PAHs) in phase-transfer experiments into a perfluorocarbon phase. Metal cation responsive tweezers In the early 2000s, Lehn and co
- . Vives and co-workers then explored the redox non-innocent properties of Ni(II)–salphen moieties to achieve a multistate system with tweezers 15 [46]. Indeed, Ni(II)–salphen complexes present two reversible oxidation waves with oxidation centered on the ligand. However, in the presence of a coordinating
- ligand (such as pyridine or pyrazine), valence tautomerism from ligand-centered oxidation to a metal-centered one is achieved due to the stabilization of an octahedral Ni(III). These properties allow the tweezers to reach six distinct and stable states by playing with three orthogonal stimuli that are
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
- -rich fluid emissions and unique sulfur oxidation–reduction reactions [1]. Due to the unique habitat, microorganisms surviving in the deep-sea cold seeps may serve as promising sources of secondary metabolites with functional and structural diversity [2]. In particular, two indole diketopiperazine
- pathway, the bergamotene sesquiterpenoid (I) is presumed to be a key intermediate cyclized from farnesyl diphosphate (FPP) via nerolidyl diphosphate (NPP) followed by a bisabolyl cation [14]. Subsequent oxidation (bishydroxylation) catalyzed by some oxygenase such as P450 would afford the key intermediate
- 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
(E,Z)-1,1,1,4,4,4-Hexafluorobut-2-enes: hydrofluoroolefins halogenation/dehydrohalogenation cascade to reach new fluorinated allene
Beilstein J. Org. Chem. 2024, 20, 452–459, doi:10.3762/bjoc.20.40
- ]. A few decades later, several new publications in this direction appeared in the literature. In a Chemours’ patent, it has been shown that the oxidation of (E)-butene 1a with sodium hypochlorite in the presence of tetrabutylphosphonium bromide leads to the formation of a bistrifluoromethyl containing
Enhanced host–guest interaction between [10]cycloparaphenylene ([10]CPP) and [5]CPP by cationic charges
Beilstein J. Org. Chem. 2024, 20, 436–444, doi:10.3762/bjoc.20.38
- reported that two-electron oxidation of [n]CPPs yields dications, [n]CPPs2+ [17][21][43], which are unusually stable due to the presence of in-plane aromaticity derived from the ring structure [19]. Therefore, we speculated that the CPP dication could be used as a host or a guest to alter the electronic
- regardless of the oxidation state of the starting CPPs. Thus, when neutral [5]CPP was mixed with [10]CPP2+ (SbCl6−)2, only the signals at 8.0 and 5.3 ppm corresponding to [10]CPP⊃[5]CPP2+ were observed (Figure 1c, path B), suggesting a quick electron transfer from [5]CPP to [10]CPP2+ has occurred. The same
- complex was also formed by mixing a 1:1 mixture of radical cations of [5]- and [10]CPP, [5]CPP•+ (SbCl6−) and [10]CPP•+ (SbCl6−), respectively (Figure 1c, path C). The observed results can be explained by two reasons; one is the oxidation potentials of [10]- and [5]CPPs. In sharp contrast to linear π
Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles
Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36
- various oxidation and hydrogenation reactions [105]. NanoAg-Pt doped silicate constitutes an efficient and recyclable catalyst that can be reused without a notable loss in catalytic activity (Scheme 17). Wanting to avoid the use of conventional heating, Karthikeyan and his co-workers turned to microwave
Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters
Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35
- absorption of light, an excited photocatalyst (*PC) engages in single-electron transfer (SET) with either donor (D) or acceptor (A) molecules (Scheme 3) [8][36]. Accordingly, a reductive quenching mechanism (path a) will operate when an excited photocatalyst effects the one-electron oxidation of a
- a reductive quenching mechanism. However, since the overall transformation is redox-neutral, no stoichiometric reductant was employed. Instead, fluorescence-quenching studies suggested that the reductive quenching of the iridium excited state (*IrIII) was taking place "off-cycle" via oxidation of
- oxidation of 35 to 36, the photocatalyst is regenerated and product 37 is formed through intramolecular nucleophilic cyclization facilitated by the phosphate base. Importantly, the activation of NHPI esters through PCET may also play a role in transformations mediated by the cyanoarene-based donor–acceptor
Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines
Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34
- , Supporting Information File 1), 2-(arylamino)-3H-phenoxazin-3-ones 4a–h manifest two reduction waves at Е1/2RED1 = −1.36 ± 1.69 V and Е1/2RED2 = −1.85 ± 2.12 V. Oxidation of 4a–f,h occurs as an irreversible process at Е1/2OX = 0.81–1.07 V. For 4g bearing an amino group, the oxidation potential is shifted to
- = −1.39 V to a radical anion and then undergoes irreversible reduction at Е1/2RED2 = −1.91 V and irreversible oxidation at Е1/2OX = 0.48 V. These CV parameters are close to those recorded for triphenodioxazines [23]. The energy of the HOMO and LUMO orbitals assessed on the basis of the CV and electronic
Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments
Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30
- precursors of π-CPCs bearing non linearly-fused benzene rings. In addition, the non-planar geometry of such heteropines appears as an asset towards increased solubility, and the existence of several oxidation states for these heteroatoms expands the panel of reaction conditions applicable to trigger the
- expected, the non-planar thiepine derivatives 3–5 exhibit substantially higher solubility in organic solvents compared with the parent PBI compounds, with a 150- to 1700-fold increase in dichloromethane depending on the sulfur oxidation state. Conversion of the dinaphthothiepine core into the corresponding
- corresponding boronic acid 9 and a Suzuki–Miyaura cross-coupling between 8 and 9 gave rise to dimer 10, followed by the oxidation of both acenaphthene units into 1,8-naphthalic anhydrides. Installation of the thiepine ring was achieved by a double nucleophilic aromatic substitution induced by sodium sulfide
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