Search results
Search for "oxime" in Full Text gives 122 result(s) in Beilstein Journal of Organic Chemistry.
Artificial bioconjugates with naturally occurring linkages: the use of phosphodiester
Beilstein J. Org. Chem. 2018, 14, 1946–1955, doi:10.3762/bjoc.14.169
- –Alder reaction [41][42][43][44], and hydrazone/oxime formation [45][46][47][48], have developed selective conjugation reactions under mild conditions. Although these bond-forming reactions have proven to be truly powerful approaches and will remain as first options to create novel bioconjugates
Drug targeting to decrease cardiotoxicity – determination of the cytotoxic effect of GnRH-based conjugates containing doxorubicin, daunorubicin and methotrexate on human cardiomyocytes and endothelial cells
Beilstein J. Org. Chem. 2018, 14, 1583–1594, doi:10.3762/bjoc.14.136
- cleavable oligopeptide spacers (e.g., GFLG, YRRL) [15][21], dimerization of the targeting GnRH-III unit [22], attachment of drugs through different linkages (e.g., ester, amide or oxime bond) [14][23], and multiplication of drugs [24][25] were pursued in order to achieve an increased antitumor effect. The
- drug conjugates. Dox has three potential conjugation sites; i) a primary OH group at C-14 on the aglycone part, which is suitable for ester bond formation, ii) an oxo group at C-13 is available for the generation of an oxime linkage and iii) the amino group on the daunosamine sugar moiety, which can be
- amide bond through the sugar moiety (glut) (2) in solution. Furthermore, an oxime linkage was formed between Dox and an aminooxyacetyl moiety connected to the enzymatically cleavable tetrapeptide spacer GFLG (3). These conjugates were prepared with the aim of comparing the influence of the homing
One hundred years of benzotropone chemistry
Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98
Hypervalent iodine-mediated Ritter-type amidation of terminal alkenes: The synthesis of isoxazoline and pyrazoline cores
Beilstein J. Org. Chem. 2018, 14, 1028–1033, doi:10.3762/bjoc.14.89
- (3a–c, 3f) [31]. However, electron-rich aryl allyl ketone oximes such as 1d, 1e and 1g proved inferior. Also the furan-substituted allyl ketone oxime delivered the desired product 3h albeit in a moderate yield. In addition, various alkyl allyl ketone oximes were investigated. While cyclopropyl allyl
- ketone oxime 1m was converted to the corresponding isoxazoline 3m in 20% yield, other alkyl allyl ketone oximes afforded higher yields of the desired products. This observation is ascribed differences in reactivity due to an increased steric bulk at the α-position (t-Bu > c-Hex > n-Oct > n-Bu). We next
- Scheme 4. First, an activation of hypervalent iodine(III) by the Lewis acid generates the active iodine(III) species A in situ. The resulting iodine(III) then, in turn, forms the electrophilic iodonium intermediate B with the terminal alkene of the allyl ketone oxime or allyl ketone tosylhydrazone. The
On the design principles of peptide–drug conjugates for targeted drug delivery to the malignant tumor site
Beilstein J. Org. Chem. 2018, 14, 930–954, doi:10.3762/bjoc.14.80
- , there are certain bonds like imine, oxime, hydrazone, orthoester, acetal, vinyl ether and polyketal [103] that are known to undergo hydrolysis at acidic pH, while being extremely stable during blood circulation. Therefore, acid-labile bonds could be hydrolyzed in the slightly acidic microenvironment and
Development of novel cyclic NGR peptide–daunomycin conjugates with dual targeting property
Beilstein J. Org. Chem. 2018, 14, 911–918, doi:10.3762/bjoc.14.78
- release; NGR peptides; oxime-linkage; targeted drug delivery; Introduction Targeted chemotherapy is one of the most promising approaches for selective cancer treatment that may decrease the toxic side effects of anticancer drugs. This therapeutic approach is based on the fact that tumor specific
- characterization of novel cyclic NGR peptides and their corresponding NGR-drug conjugates. Special attention was paid on the chemostability and in vitro biological activity of the compounds [17][18]. Daunomycin (Dau) was used as cytotoxic agent, attached to the NGR-derivatives via oxime linkage. The prepared
- spacer to the lysine side chain connected to the chatepsin B labile GFLG spacer that allows lysosomal drug release. Dau was conjugated to the GFLG spacer via oxime linkage through an incorporated aminooxyacetyl (Aoa) moiety. The preparation of the conjugate required a sophisticated synthetic route and
Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin–GnRH-III conjugates developed for targeted drug delivery
Beilstein J. Org. Chem. 2018, 14, 756–771, doi:10.3762/bjoc.14.64
- cellular uptake of the bioconjugates were strongly affected by the amino acid exchange which in turn had an impact on the antitumor activity of the bioconjugates. Keywords: cytostatic effect; daunorubicin; drug-targeting; GnRH derivatives; oxime linkage; Introduction Cancer is one of the most serious
- ester or hydrazine bonds, cathepsin-B labile spacers and oxime bonds [21][22][25]. Due to its structural properties, Dau cannot be attached to the homing device by an ester bond like Dox, because of the absence of the primary hydroxy group in position C-14. However, the C-13 carbonyl group of Dox/Dau
- provides a suitable conjugation site and can be used for the formation of oximes. We have recently reported that Dau was efficiently linked to the 8Lys side-chain by incorporation of an aminooxyacetic acid (Aoa) moiety [21][25]. The formed oxime linkage is more stable under physiological conditions than
High-yielding continuous-flow synthesis of antimalarial drug hydroxychloroquine
Beilstein J. Org. Chem. 2018, 14, 583–592, doi:10.3762/bjoc.14.45
- heterogeneous reduction with H2/Raney-nickel. Therefore, we explored an alternate strategy: simple conversion of the ketone group of 6 to oxime 11, followed by reduction to give 5-(ethyl(2-hydroxyethyl)amino)-2-aminopentane (12). We have found H2/Raney-nickel efficiently reduces 11 to 12 with THF as the solvent
- next step 6 was reacted with hydroxylamine, which was facilitated by passing through a packed-bed of K2CO3 to give oxime 11 (Table 2). As was seen with the reaction to produce 6 (Table S1 in Supporting Information File 1), reactant concentrations also had a dramatic effect on the oxime formation. A
- broad range of oxime 11 reactant concentrations. An optimum residence time was determined to be 4 hours. After optimizing the individual steps up to compound 12 the entire reaction was telescoped into a continuous reaction process that convert 10 and 6 into 12 (Scheme 4) with an overall isolated yield
Carbohydrate inhibitors of cholera toxin
Beilstein J. Org. Chem. 2018, 14, 484–498, doi:10.3762/bjoc.14.34
- a non-binding mutant of the target CTB protein [66], oxidised the N-terminal threonine residue of each subunit to an aldehyde and then chemically attached GM1os ligands by oxime ligation (Figure 15). This neoglycoprotein was able to display the five copies of the carbohydrate ligand with appropriate
Photocatalytic formation of carbon–sulfur bonds
Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4
Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles
Beilstein J. Org. Chem. 2018, 14, 11–24, doi:10.3762/bjoc.14.2
- functionalized carbohydrates (Figure 1c). Various types of reaction, such as reductive amination [32], oxime formation [33], amidation [34], and perfluorophenyl azide (PFPA) photocoupling [35][36], have been used to functionalize the surface of AuNPs with carbohydrates. The detailed information regarding the
From dipivaloylketene to tetraoxaadamantanes
Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1
- [29]. It should be noted that both the bisdioxines [19] and the tetraoxaadamantanes [29] exhibit axial chirality as confirmed by 1H NMR spectroscopy with the Eu(hfc)3 chiral shift reagent. Bisdioxine oxime and hydrazine derivatives 26 and 27 (Scheme 8) are formed from 3 at room temperature without the
- ) derived from dipivaloylketene (2). Mechanisms of formation of bisdioxine acid derivatives from dimer 3. Recently reported synthesis of chromenobisdioxines. Formation of tetraoxaadamantanes. Decarboxylative hydrolysis and oxa-Michael-type ring closure. Oxime and hydrazine derivatives of bisdioxines and
Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective
Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220
- NSA1a–c generated from the corresponding α-chloroketones (2-chlorocyclohexanone oxime (1a), 2-chlorocyclooctanone oxime (1b) and 12-chloro-сyclododeca-4,8-dien-1-one oxime (1c)) upon the action of an excess of nucleophile (Scheme 2). It was found that oximes 1b and 1c react both with diethyl malonate
- and acetylacetone, providing adducts 5 in high to quantitative yields. Six-membered cyclic oxime 1a afforded the corresponding products only in moderate yields owing to the formation of undesired side products and polymerization of the α,β-unsaturated nitroso compound. This early example demonstrates
- esters bearing electron withdrawing substituents (CO2Et, NO2, COCH3, SO2Ph) at the α-position (Scheme 5) [26]. Nitrosoalkenes were generated according to Denmark’s procedure [14] upon the action of TBAF on TBS ethers of α-chlorooximes 2. Importantly, TBS oxime ethers of various halo-substituted aldehydes
Mechanochemical synthesis of small organic molecules
Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186
- palladium-catalyzed site selective mechanochemical dehydrogenative C–H/C–H arylation between oxime and arene moiety for the construction of Csp2–Csp2 bond with high para-selectivity of arene component via LAG. Using 10 mol % of Pd(OAc)2, 2.0 equiv of Na2S2O8 and 1.0 equiv TfOH the biaryls were synthesized
Construction of highly enantioenriched spirocyclopentaneoxindoles containing four consecutive stereocenters via thiourea-catalyzed asymmetric Michael–Henry cascade reactions
Beilstein J. Org. Chem. 2017, 13, 1342–1349, doi:10.3762/bjoc.13.131
- -catalyzed Michael addition/intramolecular silyl nitronate-olefin cycloaddition (ISOC)/fragmentation sequence to produce highly enantioenriched spirocyclopentaneoxindoles containing an oxime functional group from easily accessible 3-allyl-substituted oxindoles and nitroolefins, which has received wide
Sulfamide chemistry applied to the functionalization of self-assembled monolayers on gold surfaces
Beilstein J. Org. Chem. 2017, 13, 648–658, doi:10.3762/bjoc.13.64
- formation [12][13][14], Diels–Alder reaction [15][16] or the imine/oxime condensation [17][18]. These reactions tend to produce strong covalent interactions between the surface and the molecules in solution which ensure a stable immobilization. One limitation of the covalent strategy lies in the
Transition-metal-catalyzed synthesis of phenols and aryl thiols
Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58
- according to the proposed reaction mechanism. In 2015, Jiao and co-workers employed an oxime methyl ester as directing group and achieved the hydroxylation of arenes [67]. The reaction used Pd(OAc)2 as catalyst, PPh3 or DEAD as ligand and oxone as oxidant, affording the corresponding phenols in gratifying
- hydroxylated oxime could be readily converted to o-acylphenol or o-aminomethylphenol. In 2016, Sunoj and co-workers disclosed the first meta-hydroxylation of arenes using a tethered -CN directing group [68]. The conversion proceeded at 70 °C in hexafluoro-2-propanol (HFIP) in the presence of Pd(OAc)2, PhI(TFA
- hydroxylation of benzimidazolylarenes. Dioxane mediated hydroxylation of 2-heteroarylarenes. Hydroxylation of oxime methyl ester. CN-directed meta-hydroxylation. Pd(OAc)2-catalyzed hydroxylation of benzoic acids. Pd(OAc)2-catalyzed hydroxylation of biaryl or aryl alkyl ketones. Pd(OAc)2 and Pd(TFA)2 catalyzed
NMR reaction monitoring in flow synthesis
Beilstein J. Org. Chem. 2017, 13, 285–300, doi:10.3762/bjoc.13.31
- ] studied the pros and cons of a benchtop NMR instrument at 45 MHz (Pico Spin-45). For this purpose, they studied reactions like the Fisher esterification, Suzuki reactions, and oxime formation and they analyzed the samples by simple injection of aliquots in the inlet port through an HPLC filter using non
- . [45], who developed a micro-channelled cell for synthesis and monitoring (MICCS) (Figure 8) and this was integrated into a 500 MHz NMR instrument. The system was used to elucidate the mechanism of the radical addition to an oxime ether with triethylborane (Scheme 1). The use of the NMR micro flow cell
- (a) 9 s and (b) 3 min. Stoichiometry: benzyl alcohol/DIPEA/acetyl chloride 1:1:1.2. Reproduced with permission from reference [44]. Copyright 2009 The American Chemical Society. a) Design of MICCS and b) schematic diagram of MICCS–NMR [45]. CH2Cl2 solutions of oxime ether and triethylborane were
Chemical probes for competitive profiling of the quorum sensing signal synthase PqsD of Pseudomonas aeruginosa
Beilstein J. Org. Chem. 2016, 12, 2784–2792, doi:10.3762/bjoc.12.277
- microwave assistance (Scheme 1). Thionation of the 4-position of 1, 4, 6, 10, 13 and 15 using P4S10 in pyridine under reflux conditions gave the 4-thiones 2, 5, 7, 11, 14 and 16 in yields between 60–80%, respectively (Scheme 1). The HHQ-oxime (3) was synthesized from HHQ (1) by conversion in the benzyl
- -protected chinolinol form (3a) and oximation with hydroxylamine hydrochloride similar to the described method used for the synthesis of the PQS-oxime 12 [33]. The entire compound library of HHQ and PQS analogues is presented in Figure 4. Further details on the syntheses are given in the Supporting
- HHQ (2, 5, 7) or PQS (11, 14, 16) scaffold or an oxime group in position 4 (3 and 12). The eight active compounds were tested in a concentration-dependent experiment in order to assess their potency in inhibiting probe binding. Interestingly, the HHQ derivative 3 with an oxime group was significantly
Combined experimental and theoretical studies of regio- and stereoselectivity in reactions of β-isoxazolyl- and β-imidazolyl enamines with nitrile oxides
Beilstein J. Org. Chem. 2016, 12, 2390–2401, doi:10.3762/bjoc.12.233
- of a disfavored 5-endo-trig cyclization for the corresponding intermediate oxime. Path 2 involves the initial transformation of hydroxamoyl chloride to a nitrile oxide, followed by concerted cyclization to triazolines 3a–c. We have found that introduction of electron-withdrawing substituents into the
- . Investigation of the stepwise mechanism’s pathway allowed locating the only transition state (1a_1−7), which is appropriate to the addition of nitrile oxide 2a onto the double bond of enamine 1a_1, and the respective product – oxime 7. However, the intermediate 7 was found to cyclize to isoxazoline 3a through
Practical synthetic strategies towards lipophilic 6-iodotetrahydroquinolines and -dihydroquinolines
Beilstein J. Org. Chem. 2016, 12, 1851–1862, doi:10.3762/bjoc.12.174
- also use Lewis acids [7]. The resultant quinolin-2-one is then reduced using strong hydride reducing agents such as LiAlH4 [8]. Similar THQs have also been prepared by a reductive Beckmann rearrangement of an oxime using diisobutylaluminium hydride (DIBAL) [9]. In contrast to this variety, the
A robust synthesis of 7,8-didemethyl-8-hydroxy-5-deazariboflavin
Beilstein J. Org. Chem. 2016, 12, 912–917, doi:10.3762/bjoc.12.89
- transformed to the corresponding protected ribitylamine via the oxime, which was submitted to reduction with LiAlH4. Key advantage compared to previous syntheses is the utilization of a polyol-protective group which allowed the chromatographic purification of a key-intermediate product providing the target
- . For example, the preparation of amine 5 by reduction of the oxime and its conversion with chlorouracil 3 turned out to be impossible when following a literature protocol [19]. We therefore decided to develop a robust synthesis of a protected derivative of amine 5 which could follow standard
- herein our synthetic approach to compound FO (1), which finally turned out to reliably yield the final product with high purity. Results and Discussion Synthesis of aldehyde 9 We envisioned the reduction of an oxime to be the most convenient access to the doubly isopropylidene protected amine 10 [21][22
Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds
Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23
- , the less active compound is the weak acid oxime derivative 20a. Then, the formation of the more nucleophilic aldoximate is favored with the pyridinium derivatives 20b–d, explaining their high activity. The moderate efficiency of ketoximes 20d and 20e, compared to that of the corresponding aldoximes
- detoxification by 20b was not as effective, suggesting a non-reactive position of the nucleophilic oxime to efficiently react with this toxic. Worek et al. also demonstrated the prophylaxis effect associated to 20b in the case of anesthetized guinea pigs poisoned with cyclosarin [78]. A dose of cyclosarin s.c
- degradation of tabun (Scheme 4) [80]. However, it should be pointed out that a simple glucose derivative bearing the same nucleophilic group has a similar activity. The efficiency of 20c is therefore clearly related to the pyridinium oxime functional group and not to the inclusion properties of the
Recent advances in copper-catalyzed C–H bond amidation
Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240
- chloride/anhydrides [6][7][8][9][10][11], nitrile hydrolysis [12][13][14][15][16], Goldberg C–N cross coupling reaction [17], aldehyde/ketone amidation [18][19][20][21][22][23], the transamidation [24][25][26][27][28][29], and oxime rearrangement [30][31][32][33], to name only a few. It is obvious that the
Copper-mediated synthesis of N-alkenyl-α,β-unsaturated nitrones and their conversion to tri- and tetrasubstituted pyridines
Beilstein J. Org. Chem. 2015, 11, 2097–2104, doi:10.3762/bjoc.11.226
- hydroxylamines, as well as N-alkenyl and N-arylnitrones [1][2][3][4][5]. We have discovered that when this transformation is performed with oxime and hydroxamic acid substrates, these reactive intermediates can be accessed and subsequently rearrange to a variety of challenging organic fragments and heterocyclic
- corresponding tri- and tetrasubstituted pyridines 9 (Scheme 2C). This use of α,β-unsaturated oxime reagents for the synthesis of pyridines is unique from transition metal-catalyzed C–H bond functionalization processes that require a regioselective migratory insertion. This route is appealing due to the
- modularity of the Chan–Lam coupling process, and proceeds through a pathway that is distinct from the Liebeskind copper-catalyzed C–N bond coupling and electrocyclization (Scheme 2). Results and Discussion A Chan–Lam coupling between chalcone oxime 6a and cyclohexenylboronic acid (7a) was initially tested
Other Beilstein-Institut Open Science Activities
