Latest ArticlesThe first total synthesis of marine sesquiterpene (hydro)quinone meroterpenoids dysideanones A and E–G (1 and 4–6) has been accomplished in an enantioselective and divergent way. The sesquiterpene fragment and the aromatic moiety were efficiently connected via a site-selective and diastereoselective intermolecular alkylation of Wieland–Miescher ketone derivative 9 and benzyl bromide 10. The core 6/6/6/6-fused backbone of dysideanones was efficiently constructed through an intramolecular radical cyclization reaction. Dysideanone G (6) was easily prepared on a gram-scale and dysideanones A, E, and F (1, 4, and 5) were divergently transformed from dysideanone G (6) in one or two steps
The utilization of solar-driven interfacial evaporation technology is highly important in addressing the energy crisis and water scarcity, primarily because of its affordability and minimal energy usage. Enhancing the performance of solar energy evaporation and minimizing material degradation during application can be achieved through the design of novel photothermal materials. In solar interfacial evaporation, photothermal materials exhibit a wide range of additional characteristics, but a systematic overview is lacking. This paper encompasses an examination of various categories and principles pertaining to photothermal materials, as well as the structural design considerations for salt-resistant materials. Additionally, we discuss the versatile uses of this appealing technology in different sectors related to energy and the environment. Furthermore, potential solutions to enhance the durability of photothermal materials are also highlighted, such as the rational design of micro/nano-structures, the use of adhesives, the addition of anti-corrosion coatings, and the preparation of self-healing surfaces. The objective of this review is to offer a viable resolution for the logical creation of high-performance photothermal substances, presenting a guide for the forthcoming advancement of solar evaporation technology.
A photoredox-catalyzed synthesis of α,α-difluoromethyl sulfones from sulfur dioxide with readily available gem–difluoroalkenes is reported. This protocol features mild reaction conditions, broad substrate scope and good functional group compatibility, giving rise to the target α,α-difluoromethyl sulfones in moderate to excellent yields. Mechanistic studies indicate that this reaction is initiated by an aryl radical with the insertion of sulfur dioxide.
Microplastics (MPs) are an emerging environmental pollutant and have penetrated the most remote and primitive areas. MPs degradation has received widespread attention. Manganese (Mn) is a highly reactive metal element in the environment, yet its contribution to MPs degradation remains unclear. Herein, we simulated the aging of polyethylene MPs with Mn(Ⅱ) under aqueous conditions at pH 5 and 8 for 720 days. Mn greatly promoted the MPs degradation, and the average particle sizes of polyethylene MPs were reduced from 9.2 µm to 5.9 µm after aging at pH 5 under light irradiation for 720 days. Plenty of oxygen-containing groups were generated on the MPs surfaces, and the carbonyl index remarkably increased, reaching four times that of the control without adding Mn. Mechanistically, the adsorbed Mn(Ⅱ) on the MPs surfaces were primarily oxidized to high-valence Mn(Ⅲ/Ⅳ) profited from the photoproduced radicals, followed by the MPs oxidation via Mn(Ⅲ/Ⅳ), which were reduced to regenerate Mn(Ⅱ), initiating a new redox cycling. During the degradation, dissolved organic matter was continuously released, mainly including bisphenol A and phthalic acid esters. Mn acts as a catalyst to accelerate the MPs degradation by redox cycling. Our results provide a new insight into the mechanisms of abiotic degradation of MPs in aqueous environments.
Herein, we describe a nickel-catalyzed reductive decarboxylative difluoromethylation reaction of alkenes using inexpensive and easy-to-handle difluoroacetic anhydride (DFAA)/pyridine N-oxide reagent system. A variety of C(sp3)-CF2H containing compounds were prepared through a hydrodifluoromethylation process. Besides, various gem–difluoroalkenes bearing CF2H group were synthesized via defluorinative reductive cross-coupling process from trifluoromethyl-substituted alkenes using this new reaction system. Difluoroacetic anhydride has been then extended to other common alkyl anhydrides, and the corresponding hydroalkylation and defluoroalkylation processes have been successfully achieved. This method features broad substrate scope, good functional group tolerance as well as high efficiency.
The cross-photodimerization often comes with the formation of undesired and competitive homo-photodimer as side products. Herein, we report a series of highly selective [4 + 4] cross-photodimerization between anthracene and 4a-azoniaanthracene derivatives within a cucurbit[10]uril (CB[10]) host in water. Heteroternary inclusion complexes were formed through encapsulation of donor (D1-D2, anthracene derivative) and acceptor (A1-A3, 4a-azoniaanthracene derivatives) pairs in CB[10]. In the presence of CB[10] (1.0 equiv.), the [4 + 4] cross-photodimerization between D1 and A1/A2/A3 efficiently gave a single racemic cross-photodimer. Furthermore, the cross-photodimerization between 9-substituted anthracene D2 and A1/A3 was catalyzed by CB[10] (0.1 equiv.) to quantitatively yield a cross-photodimer with high regioselectivity. Efficient formation of selective cross-photodimers could be attributed to the exclusive encapsulation of D-A hetero-guest pairs in CB[10] and the confinement effect of the CB[10] host cavity. Our study further proves host–guest complexation as a powerful strategy for cross-cycloaddition reactions with high efficiency.
Rational tuning of chiral nanostructures of supramolecular assemblies as catalysts and investigating their chiral morphology-enantioselectivity dependence is rarely reported. Herein, we report a series of supramolecular M/P-helical nanoribbons (HNs) assembled from the chiral L/D-glutamate-based amphiphiles (L/D-GluC16) and Cu(Ⅱ) ions, with their helical screw pitches adjusted from 217 nm to 104 nm through the facile regulation of their water/organic solvent assembly environment. They were then used as ideal models to reveal the chiral morphology-enantioselectivity relationship by catalyzing the asymmetric Diels-Alder reaction. Better enantioselectivity was achieved with more twist morphology. Experimental evidences of stronger chiral transfer effect from the supramolecular HNs with more twist to the aza-chalcone as reactant were obtained to understand such dependence. Our study demonstrates a new perspective for designing supramolecular catalysts with higher enantioselectivity.
Aryl ketones as photolabile protecting group (PPG) to modify purine imines is a novel nucleic acid protection strategy. Especially, photoprotection of N7-guanosine is the first reported photoprotected nucleoside that can affect the Hoogsteen recognition site of guanosine. However, the mechanism, which is pivotal to high efficiency of photorelease and applications of PPGs in biological and medical systems, is unclear. Here, a detailed deprotection mechanism of benzophenone protected guanosine (BP-Guo) at N7 position is reported. Upon irradiation, BP-Guo populates to singlet state, which generates 3[BP]-Guo via intersystem crossing process. Thereafter, triplet energy transfer competes with hydrogen atom transfer forming BP-3[Guo] and ketyl-Guo, respectively. Both species break CN bond to release guanosine. These results provide deeper insights into exploiting improved strategies for photo-protecting nucleic acids. In particular, the TTET pathway could trigger well-known cyclization reactions that brings about DNA mutagenic adducts. The latter should be avoided in developing improved strategies for photoprotecting nucleic acids.
3-Deoxy-D-manno-oct-2-ulosonic acid (Kdo) is widely distributed in bacteria, and the synthesis of Kdo-containing oligosaccharides is important for the development of novel antibiotics and immunological agents. We have recently developed a strategy to achieve α-stereocontrolled glycosylation using a C3-p-tolylthio-substituted Kdo phosphite donor. The wide substrate scope and high reactivity of the donors enabled the efficient synthesis of a series of Kdo-containing glycosides with complete α-stereoselectivity and without the formation of 2,3-ene byproducts. In this study, we improved the method by replacing the leaving group diethyl phosphite with fluoride, which enhanced the stability of the donor and led to cleaner reaction. Furthermore, the substrate range was expanded by synthesizing a series of Kdo O/C/S/N-glycosides, which also opened up a new avenue for the synthesis of CMP-Kdo synthase inhibitors.
Herein, we developed the first example of copper-catalyzed silicon radical-initiated 1,4-silylcyanation of unactivated 1,3-enynes, which provided an efficient method to access CN-bearing tri- and tetra-substituted homoallenylsilane derivatives in high yields with excellent regioselectivities. This protocol featured good functional group compatibility and broad substrate scopes, enabling the formation of C-Si bond under cheap copper catalyst with a low loading. Furthermore, this means showed potential application value in the late-stage functionalization of natural products.
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