photo-Fries Rearrangement Research Articles

A General Entry to Ganoderma Meroterpenoids: Synthesis of Applanatumol E, H, and I, Lingzhilactone B, Meroapplanin B, and Lingzhiol.

Ganoderma meroterpenoids are fungal derived hybrid natural product class containing a 1,2,4-trisubstituted benzene ring and a polycyclic terpenoid part. The representatives applanatumol E, H and I, lingzhilactone B, and meroapplanin B share the same bicyclic lactone moiety connected to the arene. Employing photo-Fries rearrangements as the key step enabled a general entry to these natural products. For the synthesis of the tetracyclic framework of lingzhiol, we made use of a powerful photoredox oxidative decarboxylation/Friedel-Crafts sequence.

A Concise Route to Keto-Bridged Polyphenols by Photo-Fries Rearrangement in Flow.

Described is a new synthetic route to bis(2-hydroxy-3,5-di-t-butylphenyl)methanone and its derivatives. The combined esterification/photo-Fries rearrangement approach enables a modular preparation of keto-bridged polyphenols. This protecting group-free process is highly atom- and step-economic, and a scalable production was easily achieved in the continuous-flow mode.

The photochemistry and photophysics of benzoyl-carbazole.

Benzoyl-carbazole and its derivatives are considered a platform for exploring processes such as room temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF). They have also been reported to exhibit dual emission, but there is a great spectral variability in the relative intensity of the emission bands reported in different studies. To better understand the fundamental photophysical properties, we set to explore BCz and its perfluorinated derivative F5BCz using spectroscopy and quantum chemical simulations. We find that the reported dual fluorescence in solution and in films results from a photochemical process (photo-Fries rearrangement), producing carbazole among other products, explaining the variation in the reported emission spectra. In addition, BCz exhibits solvent dependent TADF, which is explained by the stabilization of the charge transfer S1 state in polar solvents. F5BCz undergoes an efficient photochemical process (Mallory reaction) from its single state to produce highly fluorescent product c-F5BCz, in 40% isolated yield. This photoreactivity also proceeds in films under ambient conditions, which have significant implications on the applications of BCz-based materials for optoelectronic applications.

Comprehensive Study on Solomonamides: Total Synthesis, Stereochemical Revision, and SAR Studies toward Identification of Simplified Lead.

Solomonamides, a pair of macrocyclic peptide natural products originating from marine sources, have garnered significant attention within the synthetic community owing to their marked anti-inflammatory efficacy and intricate molecular architectures. In this paper, we present a very detailed investigation into solomonamides, including the challenges associated with the total synthesis, the evolution of our synthetic strategies, structural reassignment, synthesis of all possible stereoisomeric macrocycles, biological assessment, structure-activity relationship (SAR) studies, etc. Within the ambit of this total synthesis, diverse strategies for macrocyclization were rigorously explored, encompassing the Friedel-Crafts acylation, cyclization involving the aniline NH2 moiety, macrolactamization utilizing Gly-NH2, and Heck macrocyclization methodologies. In addition, an array of intriguing chemical transformations were devised, including but not limited to photo-Fries rearrangement, Wacker oxidation, ligand-free Heck macrocyclization, oxidative cleavage of indole, synthesis of contiguous stereocenters via substrate/reagent-controlled protocols, and simultaneous making and breaking of olefinic moieties. The findings of this investigation revealed a structurally simplified lead compound. Remarkably, the lead compound, while possessing structural simplification in comparison to the intricate solomonamide counterparts, demonstrates equipotent in vivo anti-inflammatory efficacy.

Photoreaction of nitrobenzene derivatives with alkyl thiols giving sulfonamides and derivatives

Here, we serendipitously found that photoirradiation of nitrobenzene derivatives with alkyl thiols produced sulfonamides in low yields without the addition of other reagents. We proposed a new photoreaction mechanism, in which the photo-excited nitrobenzene biradical abstracts a hydrogen atom from H-S, the resultant thiyl radical undergoes the coupling with the nitrogen atom in the nitro group, and the two oxygen atoms in the nitro group are transferred onto the sulfur atom. The photoreaction by-produced p-sulfanyl, aniline, and o-sulfonyl derivatives presumably through SRN1 mechanism from the p-substituted nitrobenzene, photo-desulfonylation, and photo-Fries rearrangement from the sulfonamide, respectively. Discovery of this photoreaction will expand the scope of the chemistry of nitro and thiol compounds, since the sulfonamides are expected to find extensive applications.

A novel UV-initiated modification process for fabricating high-performance TFC RO membrane

Thin film composite reverse osmosis (TFC RO) membrane technology has seen widespread application in seawater/brackish water desalination and wastewater treatment. However, there are still problems such as unsatisfactory perm-selectivity and anti-fouling properties, and low feasibility of membrane manufacturing process. In view of the above problems, a novel UV-initiated modification process integrating with "Semi-interpenetrating polymer networks construction" and "Photo-Fries rearrangement initiation" is proposed. TFC RO membranes with both high perm-selectivity and anti-fouling properties were prepared by introducing polymerizable molecules (MAM, SA, AM) into the aqueous phase and conducting UV irradiation during interfacial polymerization (IP) process. The results showed that under the brackish water test conditions, the water flux and NaCl rejection of the optimal modified membrane (MAM-UV) were 77.5 L m−2 h−1 and 99.44%, respectively, which are 23.8% and 0.2% higher than those of the unmodified membrane (VIR-RO), respectively. The results of the anti-fouling test showed that MAM-UV exhibited good anti-fouling properties against both bovine serum albumin (BSA) and lysozyme (LYZ). In addition, the novel UV-initiated modification process proposed in this paper has broad prospects for industrial application because of its simple operation and easy scale-up.

A Review of Synthesis Methods of Chalcones, Flavonoids, and Coumarins

Chalcones are the principal precursors for the biosynthesis of flavonoids and isoflavonoids. A three-carbon α, β-unsaturated carbonyl system constitutes chalcones. Chalcones are the condensation products of an aromatic aldehyde with acetophenones in attendance of catalyst. A lot of methods and schemes have been reported for the synthesis of these compounds. Amongst all, Aldol condensation and Claisen-Schmidt condensation reactions are the most cited synthetic protocols in literature, nevertheless, Suzuki reaction, Witting reaction, and Photo-Fries rearrangement have also been utilized as synthetic protocols towards the chalcone framework. Several catalysts have been developed in the synthesis of the chalcone framework among which SOCl 2 natural phosphate, lithium nitrate, amino grafted zeolites, zinc oxide, water, K 2 CO 3 , PEG400, silica sulfuric acid, ZrCl 4, and ionic liquid are the most cited ones. The development of better synthetic techniques for the synthesis of α, β- unsaturated carbonyl compounds is still remaining high demand. Keywords: Chalcones, Aldol condensation, Claisen-Schmidt condensation, Suzuki reaction, Witting reaction, Photo-Fries rearrangement DOI: 10.7176/CMR/14-3-01 Publication date: August 31 st 2022

Optimizing interfacial polymerization with UV-introduced photo-fries rearrangement for enhancing RO membrane performance

To conveniently and environmentally friendly improve the performance of polyamide thin film composite (PA-TFC) membrane, a novel method associated with UV was presented in this study. In the process of the interfacial polymerization (IP), the UV irradiation procedure was performed to initiate photo-Fries rearrangement of PA, optimizing the membrane properties (i.e. thickness, membrane charge, hydrophilicity), and enhancing the membrane performance (i.e. permeability, selectivity, and anti-fouling performance). In comparison with the virginal PA-TFC membrane (virgin-RO), the resulting membrane (UV-13) exhibited an increased water flux of 75.9 L/m2·h (LMH, increased by 15.5%), and NaCl rejection of 99.34% (increased by 0.87%). Especially, the selectivity of UV-13 was dramatically enhanced, which can be concluded from that the salt permeability coefficient of UV-13 (5.04 × 10-4 m/h) is only half of that of virgin-RO (10.21 × 10-4 m/h). Furthermore, a series of membranes were fabricated by changing MPD concentration, TMC concentration and IP duration, and the corresponding separation performance were enhanced more or less, which may demonstrate that UV irradiation has the potential to be widely applied for enhancing PA-TFC RO membrane performance. Furthermore, UV-13 presents enhanced antifouling performance in comparison of virgin-RO, according to the results of artificial pollution tests of bovine serum albumin (BSA) and lysozyme (LYZ). Theoretically, for the RO membranes synthesized via IP process with aromatic amine monomers and aromatic acyl chloride monomers, this method is able to effectively improve the membrane performance, and has enormous potential in industrialization.

A Review of Synthesis Methods of Chalcones, Flavonoids, and Coumarins

Chalcones are the primary building blocks for flavonoids and isoflavonoids production. Chalcones are a three-carbon, -unsaturated carbonyl system. Chalcones form when an aromatic aldehyde reacts with acetophenones in the presence of a catalyst. For the synthesis of these molecules, a variety of methods and approaches have been reported. The Aldol condensation and Claisen-Schmidt condensation reactions are the most commonly referenced synthetic protocols in the literature, but the Suzuki reaction, Witting reaction, and Photo-Fries rearrangement have also been employed as synthetic procedures within the chalcone framework. SOCl₂ natural phosphate, lithium nitrate, amino grafted zeolites, zinc oxide, water, K₂CO₃, PEG400, silica sulfuric acid, ZrCl₄, and ionic liquid are among the most commonly used catalysts in the synthesis of the chalcone framework.

Induced selectivity in the photochemistry of estrone derivatives in sustainable and micellar environment: preparative and mechanistic studies

In this study, we carried out preparative and mechanistic studies on the photochemical reaction of a series of 3-acylestrone derivatives in confined and sustainable micellar environment under steady-state conditions and the results were compared with those obtained in cyclohexane solution. The aim of this work is mainly focused to show whether the nature of the surfactant (cationic, neutral and anionic) leads to noticeable selectivity in the photoproduct formation. The 3-acylestrone derivatives underwent the photo-Fries rearrangement, with concomitant homolytic fragmentation of the ester group and [1;3]-acyl migration. This pathway afforded the ortho-acyl estrone derivatives, the main photoproducts together with estrone. However, epimerization of the ortho regioisomer 2-acetylestrone and estrone through Norrish Type I photoreaction occurred involving the fragmentation of the C-α at the carbonyl group (C-17) of the steroid. UV-visible and 2D-NMR (NOESY) spectroscopies have been employed to measure the binding constant Kb and the location of the steroids within the hydrophobic core of the micelle.

Heterogeneous Functional Dielectric Patterns for Charge-Carrier Modulation in Ultraflexible Organic Integrated Circuits.

Flexible electronics have gained considerable attention for application in wearable devices. Organic transistors are potential candidates to develop flexible integrated circuits (ICs). A primary technique for maximizing their reliability, gain, and operation speed is the modulation of charge-carrier behavior in the respective transistors fabricated on the same substrate. In this work, heterogeneous functional dielectric patterns (HFDP) of ultrathin polymer gate dielectrics of poly((±)endo,exo-bicyclo[2.2.1]hept-ene-2,3-dicarboxylic acid, diphenylester) (PNDPE) are introduced. The HFDP that are obtained via the photo-Fries rearrangement by ultraviolet radiation in the homogeneous PNDPE provide a functional area for charge-carrier modulation. This leads to programmable threshold voltage control over a wide range (-1.5 to +0.2V) in the transistors with a high patterning resolution, at 2V operational voltage. The transistors also exhibit high operational stability over 140 days and under the bias-stress duration of 1800s. With the HFDP, the performance metrics of ICs, for example, the noise margin and gain of the zero-VGS load inverters and the oscillation frequency of ring oscillators are improved to 80%, 1200, and 2.5kHz, respectively, which are the highest among the previously reported zero-VGS -based organic circuits. The HFDP can be applied to much complex and ultraflexible ICs.

Photo/Thermal Dual Responses in Aqueous-Soluble Copolymers Containing 1-Naphthyl Methacrylate

Photoresponsive polymers capable of luminescence switching are attracting significant interest due to their potential application in fluorescence patterning, bioimaging, optical data storage, and anti-counterfeiting. In this work, we have developed aqueous-soluble copolymers of 1-naphthyl methacrylate and oligo(ethylene glycol) methyl ether methacrylate [P(1-NMA-co-OEGMA)] that undergo a significant shift in fluorescence emission wavelength after UV irradiation. Irradiation of the 1-naphthyl methacrylate moieties results in the photo-Fries rearrangement to form hydroxy aryl ketones, which exhibit strong emission at 475 nm through excited-state intramolecular proton transfer (ESIPT) and excited-state proton transfer (ESPT). The resultant shift in fluorescence emission maximum from 338 to 475 nm after rearrangement can potentially be exploited for fluorescence patterning. Furthermore, the copolymers are thermally sensitive in aqueous solutions. The lower critical solution temperature (LCST) of the copolymers depends on the content of hydrophobic 1-naphthyl methacrylate units; the photo-Fries rearrangement results in a more polar structure, shifting the LCST to a higher temperature. Of note, the temperature-triggered volume phase transition of copolymer hydrogels selectively ″switches off″ fluorescence arising from the ESPT mechanism, while the ESIPT emission is unaffected. We also demonstrate that films formed by coating the copolymers onto various substrates can be selectively patterned to form gradients in fluorescence intensity. These versatile P(1-NMA-co-OEGMA) copolymers are simple to prepare at low cost, demonstrate effective photoswitching, and have excellent water solubility, thus ensuring potential applications in a number of important areas.

Effects of Anthracene Doping Ratio and UV Irradiation Time on Photo-Fries Rearrangement of Polycarbonate

Thin films of pure polycarbonate (PC) with anthracene doping PC films for different doping ratios (10, 20, 30, 40, 50 and 60 ml) were prepared by using a casting method. The influence of anthracene doping ratio on photo-fries rearrangement of polycarbonate was systematic investigated. Furthermore, pure PC and anthracene doping PC films were irradiated via UV light at a wavelength (254 nm) for different periods (5, 240, 288, and 360 hrs). The photo-fries rearrangement occurring in pure PC and anthracene doping PC films were monitored using UV and FTIR spectroscopies. The photo-fries rearrangement leads to scission the carbonate linkage and formation phenylsalicylate and dihydroxybenzophenes. The result of the UV spectrum confirms disappear of polycarbonate peaks, while phenylsalicylate and dihydroxybenzophenone peaks appear at (320 nm) and (360 nm), respectively. The formation of a dihydroxybiphenyl compound reveals when the UV peak distinguishes at (340 nm). FTIR spectroscopy supported forms of phenylsalicylate and dihydroxybenzophenone compounds which appear in carbonyl region at (1689 cm-1) and (1630 cm-1), respectively. It founds that anthracene accelerates the photo-fries rearrangement of polycarbonate in the anthracene doping PC films because anthracene leads to formation of excited singlet state oxygen (1O2). Singlet oxygen (1O2) leads to the formation of a hydro peroxide, which could decompose and cause to chain scission and formation of a terminal of a carbonyl group. The presence of the carbonyl groups in the polymer makes it photo-labile, also warns that the polymer is vulnerable to deterioration.

Photochemical Behavior of Some Estrone Aryl and Methyl Sulfonates in Solution: Preparative and Mechanistic Studies

Direct irradiation of estrone aryl and methyl sulfonates in different organic solvents under nitrogen atmosphere was investigated under steady-state conditions. The estrone derivatives reacted efficiently through the photo-Fries rearrangement reaction involving [1;3]-sulfonyl migration providing the ortho-sulfonyl estrone derivatives and estrone as the photoproducts. In addition, estrone and 2-arylsulfonyl estrone derivatives were epimerized involving a Norrish Type-I reaction. Chemical quenching and photosensitization experiments on the photoreaction have been also carried out to establish the photoreactive excited state. Likewise, the solvent effect and the nature of the sulfonyl group on the photoreactions have been also studied.

Photo-Fries rearrangement in flow under aqueous micellar conditions.

A flow edition of photo-Fries rearrangement for the synthesis of 2-acylphenols in an aqueous micellar medium has been described. We take advantage of a narrow channel reactor and micelle-induced confinement effect to refine both the efficiency and selectivity of the parent photoreaction.

Influence of UVB-Irradiation on the Structures and Solid Particle Erosion Resistance for CF/PC Composites

The service life and properties of Carbon fiber reinforced polycarbonate (CF/PC) composites are seriously affected by ultraviolet radiation from outdoor exposure during aging. In this work, the changes of structure and solid particle erosion resistance for CF/PC composites after ultraviolet irradiation were studied. It was shown that ultraviolet irradiation causes photo-oxygen aging and photo-fries re-arrangement of the composite, and the result was confirmed by FTIR. We correlated the solid particle erosion resistance with aging time, and found that the solid particle erosion resistance of CF/PC composites greatly decreased by UVB irradiation during 15 hours. Furthermore, the eroded material surface was analyzed using scanning electron microscope (SEM). It suggests that ultraviolet aging leads to plasticization and degradation, resulting in reduction of erosion resistance of the composite.

Total Synthesis of Caesalpinnone A.

Total synthesis of caesalpinnone A was achieved in 12 steps starting from resorcinol. Key features of the synthesis include BINOL-phosphoric acid catalyzed [4 + 2] cycloaddition, trans-selective nucleophilic substitution, deallylation/oxa-Michael addition cascade, and late-stage photo-Fries rearrangement.

Photoinduced Reorientation in Thin Films of a Nematic Liquid Crystalline Polymer Anchored to Interfaces and Enhancement Using Small Liquid Crystalline Molecules.

The photoinduced reorientation of the side-chain mesogens in nematic liquid crystalline (LC) polymer thin films triggered by the axis-selective photo-Fries rearrangements of side-chain phenyl benzoate moieties is studied to understand the regulation of the anisotropic nanostructures supported by LC polymers. The influence of the substrate surface in anchoring the side-chain mesogens near the interfaces is examined by comparing the reorientation of 30- and 120-nm-thick films. Irradiation with linearly polarized ultraviolet (UV) light and subsequent annealing causes the side-chain mesogen reorientation to align perpendicular to the electric field of the incident UV light. The inplane order in the 30-nm-thick films is lower than that in the 120-nm ones. On the other hand, the annealing period required for mesogen alignment is independent of the film thickness. It is suggested that the substrate surfaces anchor the LC mesogens to fix their orientation, rather than slowing down the reorientational motion. In addition, it is demonstrated that small LC molecules miscible with the nematic LC polymer enhance photoinduced reorientation through cooperative molecular interaction with the side-chain mesogens, remarkably accelerating the orientation and improving the inplane order of the unidirectionally aligned mesogens.

Refractive Index Modulation by Photo-Fries Rearrangement of Main Chain-Type Aromatic Polyurethanes

Refractive Index Modulation by Photo-Fries Rearrangement of Main Chain-Type Aromatic Polyurethanes

Photo-Fries Rearrangement of Some 3-Acylestrones in Homogeneous Media: Preparative and Mechanistic Studies.

Irradiation of a series of 3-acylestrones under a nitrogen atmosphere in cyclohexane, acetonitrile (MeCN), and methanol (MeOH) was investigated under steady-state conditions. The molecules underwent the photo-Fries rearrangement, with concomitant homolytic fragmentation of the ester group and [1;3]-acyl migration. This pathway afforded the ortho-acyl estrone derivatives, the main photoproducts, together with estrone. During the irradiation of 3-benzoyl estrone, epimerization of estrone through the Norrish type I reaction occurred, providing lumiestrone as the photoproduct. This photoreaction involves the fragmentation of the C-α at the carbonyl group (C-17) of the steroid. On the other hand, epimerization of ortho-regioisomer 2-acetyl estrone occurred during the irradiation of 3-acetyl estrone. Photosensitization with acetone and chemical quenching with N, N, N, N-tetramethyldiazetinedioxide of the photo-Fries reaction confirmed that the photoreaction took place from the singlet excited state while the Norrish type I reaction proceeds efficiently from the triplet excited state. Solvent effects, as well as the nature of the acyl group on the photoreactions, were also studied.