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Search for "visible" in Full Text gives 554 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
A Diels–Alder probe for discovery of natural products containing furan moieties
Beilstein J. Org. Chem. 2024, 20, 1001–1010, doi:10.3762/bjoc.20.88
- existing route [20] and is inexpensive ($1.80/g of starting material) to make in large quantities. It also contains a chlorine group as its MS tag, which can be easily identified via its 3:1 isotopic ratio when run on a UPLC-MS, and a phenyl ring, which allows it to be UV visible at 214 nm and 254 nm. Once
Carbonylative synthesis and functionalization of indoles
Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87
- process was catalyzed by visible light in the presence of Mo(CO)6 (1 equiv) as CO source, I2 (2 equiv), and K2CO3 (3 equiv) at 120 °C in an inert reaction environment (N2) and in DMSO as solvent (Scheme 38). Functionalization through direct C–H carbonylations The direct functionalization of indoles via C
Synthesis and properties of 6-alkynyl-5-aryluracils
Beilstein J. Org. Chem. 2024, 20, 898–911, doi:10.3762/bjoc.20.80
- of different functional groups was tested. The influence of different functional groups on the physical properties was studied by ultraviolet–visible (UV–vis) and fluorescence spectroscopy, providing new insights into the potential applications of uracil-based structures. Keywords: catalysis; cross
- . Applications and tolerance to a wide range of functional groups have been tested. Furthermore, their physical properties were analyzed by ultraviolet–visible and fluorescence spectroscopy. Results and Discussion Synthesis The synthetic strategy for the desired compounds is based on a four-step sequence
Advancements in hydrochlorination of alkenes
Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72
- functional group tolerance. Yang reported a hydrochlorination promoted by visible light over platinum, gold, and palladium supported on zirconia [74]. The reaction demonstrated moderate efficiency, yielding an 85:15 mixture of products 100 and 126 with low conversion (Scheme 20). The use of hydrochloric acid
- . Formation of chlorophosphonium complex 104 and the reaction thereof with H2O. Snyder’s hydrochlorination with stoichiometric amounts of complex 104 or 108. In situ generation of HCl by mixing of MsOH with CaCl2. First hydrochlorination of alkenes using hydrochloric acid. Visible-light-promoted
Synthesis and characterization of water-soluble C60–peptide conjugates
Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71
- most other solvents. C60–oligo-Lys and C60–oligo-Glu were characterized by 1H and 13C NMR. Photoinduced 1O2 generation was observed in the most soluble C60–oligo-Lys conjugate under visible light irradiation (527 nm) to show the potential of this highly water-soluble molecule in biological systems, for
- . Additionally, 5a exhibited broad absorption in the visible region with relatively low intensity as well as a distinctive sharp peak at around 430 nm [48]. However, those features were not observed in the spectrum of C60–oligo-Glu (5b), presumably due to the aggregation [32]. The 1H NMR spectrum of C60–oligo
- the HRESIMS results (Figure S2, Supporting Information File 1), it was confirmed that the highly water-soluble compound 5a was successfully synthesized. 1O2 generation under visible light irradiation To preliminarily evaluate the synthesized C60–oligo-Lys (5a) as a PS, generation of singlet oxygen was
Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines
Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59
- Geng-Xin Liu Xiao-Ting Jie Ge-Jun Niu Li-Sheng Yang Xing-Lin Li Jian Luo Wen-Hao Hu Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, Guangdong 510006, China 10.3762/bjoc.20.59 Abstract Herein, we report a visible
- reaction of diazo compounds mediated by visible light has been reported by the group of Gevorgyan, which achieves the monofunctionalization of alkenes [52]. Inspired by these collective studies, we considered diazo compounds could be a competent activated alkyl halide equivalent to overcome the synthetic
- (PPh3)2Cl as catalyst, the model reaction also afforded the corresponding product 4a in 31% yield, demonstrating the H–Pd(II)–X species could be a possible catalytic species (Scheme 4d). According to the UV–visible spectra, the only absorbing species at 467 nm consists in the pre-catalytic system Pd(OAc
Enhanced reactivity of Li+@C60 toward thermal [2 + 2] cycloaddition by encapsulated Li+ Lewis acid
Beilstein J. Org. Chem. 2024, 20, 653–660, doi:10.3762/bjoc.20.58
- absorption spectra showed broad absorption in the visible region with an absorption maximum at 711 nm, which was known to show a characteristic pattern of functionalized fullerene having an addend on a [6,6] bond [26]. As mentioned above, a distinctive feature of this reaction is the significantly lower
Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2Н)-ones with a terminal phenanthroline group
Beilstein J. Org. Chem. 2024, 20, 552–560, doi:10.3762/bjoc.20.47
- change depending on the intensity of sunlight), photochromic tags for biological research and optical sensors [15][16][17][18][19][20][21]. To develop new dual-mode molecular switches capable of efficient modulation of optical and fluorescent properties, both upon irradiation with visible light and upon
- -Acylated compounds 2a–c in solutions exhibited fluorescence in the region of 465–468 nm, and the excitation emission spectra agreed well with the absorption spectra (Figure 1). Compounds 2a–c in solutions demonstrated a typical negative photochromism [1][16] when irradiated with visible light of 436 nm
Switchable molecular tweezers: design and applications
Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45
- signals in the low-range visible/NIR region. Upon protonation of the pyridine, the conformation switch leads to a spatial separation of the active Pt moieties and a release of the guest (Figure 4). Also, the same group demonstrated the induction of chirality and fluorescence with chiral guest molecules
- bearing this time alkynylplatinum(II)–terpyridine arms 21 [53]. The intercalation of an alkynylplatinum(II)–terpyridine complex system results in a large absorption band in the visible domain (λmax,abs = 515 nm) and an enhanced emission band in the infrared (λmax,emission = 780 nm) attributed to the
Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination
Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43
- a buildup of alkylgold intermediates. Even at 10 and 20 mol % catalyst with urea 1a (0.05 M) in CD3OD, where gold intermediates would be significantly more visible, no alkylgold was detected. In our previous report where alkylgold buildup is observed, we know a faster catalytic process is possible
- data plots; where not visible they are smaller than the icon for the data point. (a) Schematic for synthesis of [L–Au–L]SbF6 where L = JPhos. (b) Perspective drawing of the cation in crystalline [Au(P(C4H9)2(C12H9))2](SbF6)CH2Cl2 where P are represented by dotted spheres, Au atoms are represented by
- CH3OH reproduced in Figure 2, Table 3. (b) kobs for reaction of carbamate 1b (0.05 M) in DCM with catalyst 5 and titrated CH3OH/CD3OD. Error bars are from linear least squares analysis of raw data plots; where not visible they are smaller than the icon for the data point. Rate of urea 1a (0.05 M
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
- points were determined by an SGW X-4 micro-melting point apparatus. Optical rotations were measured in MeOH using an Optical Activity AA-55 polarimeter. UV spectra were obtained with a PuXi TU-1810 UV–visible spectrophotometer. NMR spectra data were recorded on a Bruker Avance 500 or 600 MHz spectrometer
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
- absorption bands in the visible region and characteristic broad absorption bands extending to the NIR region (≈2000 nm) (Figure 4, black line). According to time-dependent density functional theory (DFT) calculations at the ωB97-XD/6-31G* level of theory, the NIR absorption of the most thermodynamically
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
Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters
Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35
- readers to recently published review articles for additional discussion [30][31]. Discussion Mechanism under photochemical conditions In this section we provide a summary of the various conditions and activation modes employed in radical reactions of NHPI esters using visible-light irradiation. Upon
- type addition reactions (Scheme 4A). In 1991, Okada and co-workers reported the addition of alkyl radicals to α,β-unsaturated ketones, by subjecting NHPI esters to visible-light irradiation in the presence of the photocatalyst [Ru(bpy)3]Cl2 and the reductant 1-benzyl-1,4-dihydronicotinamide (BNAH) [37
- ], have been employed as suitable photocatalysts (Scheme 4B). Under visible light irradiation the photocatalyst (PC) is excited into its corresponding excited state (*PC), where it can be reduced by a suitable electron donor such as DIPEA or Hantzsch ester to generate the reduced form of the photocatalyst
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
- stability. Conversely, selenepine 28c and selenepine Se-oxide 29c were quantitatively converted into the seco-HBC 31 by thermal activation at 200 °C for 5 min, as evidenced by UV–visible absorption and HPLC monitoring. SO-extrusion from thiepine S-oxide 29b was also successfully triggered in the solid state
- , which have been shown to be particularly sensitive to light [70]. Upon exposure to UV or visible light, thiarubrine A (36) undergoes a desulfurization process to give rise to the corresponding thiophene 37, exhibiting enhanced antibiotic activity (Scheme 10, bottom). This naturally-occurring S-extrusion
- sulfur and regenerate the initial 5-membered carbocycle, the thiopyran scaffold in (H2)n@52 was first oxidized with m-CPBA to yield the corresponding sulfoxide (H2)n@53. As a key step, the latter was next subjected to photoinduced SO-extrusion under visible light, leading to a ring contraction in 86
Nucleophilic functionalization of thianthrenium salts under basic conditions
Beilstein J. Org. Chem. 2024, 20, 257–263, doi:10.3762/bjoc.20.26
- Abstract In recent years, S-(alkyl)thianthrenium salts have become an important means of functionalizing alcohol compounds. However, additional transition metal catalysts and/or visible light are required. Herein, a direct thioetherification/amination reaction of thianthrenium salts is realized under metal
- ]. Recently, Ritter and co-workers reported that alkylthianthrenium salts can be employed to undergo reactions with N/O-nucleophiles under photocatalytic conditions [46]. Nevertheless, additional transition metal catalysts, visible light, or electrochemical devices are required for the reported works
Photochromic derivatives of indigo: historical overview of development, challenges and applications
Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23
- new level of complexity and promise. The photochromic indigos represent a relatively rare type of visible-light-responsive T-type photoswitches demonstrating negative photochromism. The absorption of the photoswitchable indigos covers the spectral range from green to NIR light (≈550–700 nm) making
Comparison of glycosyl donors: a supramer approach
Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18
- , 137.3 (Ph), 158.4 (q, JC,F = 38, COCF3), 167.7 (COCH2Cl), 168.1 (COCH2Cl), 168.4 (CO2Me). Note: the values of the coupling constants (JC,F) were calculated using positions of the two central signals of the multiplet; two side lines of the multiplet are not visible due to low signal-to-noise ratio. 19F
- % unless specified otherwise, see the error bars; the error bar is on the order of the symbol size if not visible). The standard deviations were calculated by using the Student’s distribution (95% probability). The grey boxes in the figure are drawn to guide the eye and designate different ranges of
Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes
Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13
- , the ensuing RE process yields the corresponding TCBD derivatives. The resulting TCBDs and related products exhibit strong light absorption, resulting from the intramolecular charge transfer (ICT) in the visible region; they also exhibit a rich redox chemistry [11]. In the [2 + 2] CA–RE reaction of
- in the visible region were evident in their CD spectra. Using the Arrhenius and Eyring formalisms, the kinetic parameters for the thermal racemization of 57 and 58 were obtained. The activation free enthalpy (ΔG‡) for the racemization of 57 (ΔG‡298 K = 24.8 kcal mol−1) was ≈1.5 kcal mol−1 larger than
- [138]. Compounds 55 and 56 remain devoid of emissive characteristics even when in a solution or a solid state [129]. When compound 50 was characterized using a standard steady-state fluorimeter, no emission signals were observed across the visible and NIR regions extending up to 1,600 nm, both in a
Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles
Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12
- Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China 10.3762/bjoc.20.12 Abstract A visible-light-promoted research protocol for constructing dihydropyrido[1,2-a]indolone skeletons is herein described proceeding through a cascade cyclization mediated by trifluoromethyl
- -reductive quench process (Table 1). The indole substrate 1a was chosen as a model substrate, and the reaction mixture was irradiated under 450 nm visible light for 12 h, resulting in the formation of the desired product 3a, albeit in a relatively low yield (Table 1, entry 1). Control experiments revealed
- 450 nm visible light irradiation is optimal (Table 1, entries 9–12). Furthermore, various types of Umemoto’s reagent were also screened (Table 1, entries 13–15). As Umemoto’s reagent 2b was easier to prepare [29] and the use of 2b did not significantly affect the reaction yield, it was chosen as the
Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor
Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9
- photon flux density, c0 is the photocatalyst concentration, and kr is the recombination rate. The linear correlation between reaction rate and photon flux visible in Figure 12b indicates that the system is still in regime 1 and the hydrogen generation rate is limited by the available photon flux, even
Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units
Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8
- Hex group in 11) on the nitrogen atom in the pyrrole ring have an effect on the absorption in the visible spectrum of pyrrolo-annelated IF-DTF ketones. Interestingly, the absorption of the dihydropyrrole IF-DTF 9 is redshifted relative to that of the pyrrole IF-DTF 4, while the absorption does not
- was observed for compound 27 was also observed for this compound. The degradation of compound 20 in the presence of light and oxygen is visible as a color change upon leaving a sample of the compound in solution in an open vial, unshielded from light (Figure S2 in Supporting Information File 1). This
- , incorporating different dithiafulvenes and acetylenic scaffolds, such as acetylenic radiaannulenes. The compounds have strong absorptions in the visible region and undergo reversible (or quasi-reversible) oxidations and reductions. We have also presented two new fluorene-extended dithiafulvenes, which also
Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water
Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5
- similar to AA [12][13], indicating self-assembly via the hydrophobic effect and π-stacking interactions (Figure 3a,b). The self-assembly in water was further supported by UV–visible analysis, displaying slight red-shifts of the anthracene absorption bands relative to the spectrum in methanol (Δλmax = +3
- the self-assembly of in average six PA-CH3 amphiphiles into a small aromatic micelle (Figure 3g). In a similar way, the generation of micelles (PA-OCH3)n, (PA-OH)n, and (PA-Im)n was confirmed via NMR, UV–visible, and DLS analyses upon dissolution of the corresponding amphiphiles in water (Figure 3c,d
- H2O (2.7 mL), the suspension was sonicated with a probe sonicator (40 kHz, 150 W, 10 min), centrifuged (16,000g, 10 min), and then filtrated (200 nm pore-size membrane filter) to yield a clear brown solution containing host–guest composite (PA-OCH3)n·(C60)m. The UV–visible analysis clearly showed new
Aldiminium and 1,2,3-triazolium dithiocarboxylate zwitterions derived from cyclic (alkyl)(amino) and mesoionic carbenes
Beilstein J. Org. Chem. 2023, 19, 1947–1956, doi:10.3762/bjoc.19.145
- stretching vibration of the S=C–S− group, another strong absorption was clearly visible in the IR spectra of CAAC·CS2 betaines 4a–c. This second most intense band was observed around 1550 cm−1 (Table 2). It probably originated from the asymmetric stretching of the aldiminium group, in line with similar high
Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides
Beilstein J. Org. Chem. 2023, 19, 1912–1922, doi:10.3762/bjoc.19.142
- (Figure 4a) show significant spectral evolution within the first 1 ps following photoexcitation at 350 nm in MeCN. The (negative) bleach feature at 450 nm and photoinduced absorption (PIA) peaking at 775 nm transform into a broad PIA spanning the visible wavelengths with a notable isosbestic point at 600
- -DMBI)2 with a broad PIA spanning the visible wavelengths, which may suggest that the initial evolution observed in the (N-DMBI)2 occurs within our instrument response. In toluene, the signal amplitude at 5 ns for (Cyc-DMBI)2 is significantly smaller than that of the (N-DMBI)2 and 96% of the signal
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