Herein, we have developed a strategy of Rh(III)-catalyzed C–H activation of N-nitrosoanilines and iodonium ylides to construct novel tetralydrocarbzol-4-one scaffolds, which provided valuable templates for sequential C-H functionalization such as alkylation, alkenyla-tion, amidation and (hetero)arylation at C5-position of tetralydrocarbzol-4-one with different coupling partners. Gram-scale synthesis and further transformation of tetralydrocarbzol-4-one derivatives to Ondansetron and its analogues demonstrated the utility of this protocol, which enabled the concise and diverse construction of biologically active molecules.
Pd-catalyzed asymmetric allylic C−H functionalization has emerged as a powerful tool to access chiral, densely functionalized molecules from easily ac-cessible alkenes, enabling the increase of the step- or atom-economy by minimizing functional group manipulations for preparing allylating reagents. Due to the inadequacy of stereoselection strategies, the asymmetric allylic C-H functionalization is still in the early stage. In this essay, we will describe our journey to identification of asymmetric catalytic systems, mechanism of allylic C−H activation, control of stereo- and regioselectivity, and applica-tions in asymmetric synthesis.
By employing thiazole and 4-chlorothiazole as the A′ units, two A-D-A′-D-A type nonfused-ring electron acceptors (NFREAs) Tz-H and Tz-Cl were designed and synthesized. Replacing thiazole in Tz-H with 4-chlorothiazole can not only remarkably shorten the synthetic route through C-H direct arylation but also enhance molecular planarity with the simultaneous incorporation of S···N and S···Cl non-covalently conformational locks (NoCLs). The photovoltaic devices based on PM6:Tz-Cl exhibited a power conversion efficiency as high as 11.10%, much higher than that of PM6:Tz-H (6.41%), mainly due to more efficient exciton dissociation, better and more balanced carrier mobility, less charge recombination, and more favorable morphology. These findings demonstrate the great potential of NoCLs in achieving low-cost and high-performance NFREAs.
Indole-based atropisomers are a very important class of axially chiral compounds. However, the atroposelective synthesis of axially chiral 2-arylindole remains largely unexplored. In this study, we report the successful synthesis of atropisomeric 2-arylindoles using direct amination of indoles with p-quinonediimines in the presence of chiral phosphoric acid as a catalyst. Quinonediimine acts as an aminating reagent through formal polarity inversion of imine. The malonate group on the 2-aryl of 2-indoles was found to be essential for high enantioselectivity of the products. This could be due to the additional interaction between the ester group and the catalyst, as well as the intramolecular hydrogen bonding. Our findings provide a new strategy for the asymmetric construction of 2-arylindole atropisomers.
The [2.2]paracyclophane-derived oxazole-pyrimidine ligands with planar chirality (PYMCOX) were designed, synthesized and successfully applied in nickel-catalyzed asymmetric 1,2-reduction of α,β-unsaturated ketones, affording the chiral allylic alcohols with up to 99% yield and 99% ee. Meanwhile, this reduction reaction could be conducted on gram-scale without loss of activity and enantioselectivity, and the chiral ligand could be conveniently recovered with high yield.
The asymmetric hydrogenation of N-heteroarenes provides an efficient method for the synthesis of optically active cyclic secondary amines. In this paper, we described an asymmetric hydrogenation of phenanthridines using a chiral mono-alkene-derived borane. A variety of dihydrophenanthridines were furnished in high yields with up to 93% ee. The current catalytic system was very sensitive for the steric hindrance of phenanthridines. Bulky substituents at one phenyl group of phenanthridines were required to obtain the high enantioselectivity. But large substituents adjacent to the C=N bonds would diminish the reactivity sharply.
A metal-free, green, and sustainable functionalization of unactivated alkyl sp3 C–H bonds is reported using iodine (III) as a feasible dehydrogenation agent under visible light or KBr, and alkyl chlorides, bromides, alcohols, and ketones could be constructed by addi-tion of different coupling reagents. Cheap and safe iodobenzene diacetate was used to form a strong radical to activate the alkyl sp3 C–H bond in a highly efficient manner, which can construct different alkylation products by adding corresponding coupling reagents.
A straightforward electrochemical hydrogenation of benzo[b]thiophene 1,1-dioxides with HFIP as the hydrogen donor has been re-ported in an undivided cell under metal-free conditions. Moreover, the tolerance of various functional groups and scaled-up experi-ments showed the practicability and potential applications of this methodology.
The issue of energy consumption has garnered significant interest due to its excessive usage. Recently, thermoelectric devices have been getting increased attention, as they can harness waste heat from various sources, such as solar radiation, human body, and industrial processes. Traditionally, the recovery of low-grade heat has been a challenge, resulting in unsustainable energy use and significant losses. While considerable advances have been made in thermoelectric materials in recent decades, the majority of these devices still primarily employ semiconductors. Nevertheless, the emergence of quasi-solid-state thermoelectric materials represents a novel devel-opment with profound promise for the environment and society. These materials offer several advantages, such as improved energy conversion capacities, cost-effectiveness, versatility, and scalability, to support increased usage. Additionally, this review explores the application of thermoelectric materials in self-powered sensors, integrated modules, and heat harvesting management. Lastly, the po-tential of high-performance thermocouples based on thermogalvanic effects is assessed, along with the challenges that must be over-come to realize this goal.
α-Olefins as aliphatic terminal alkenes could be obtained easily from numerous contemporary synthetic reactions as well as petrochemical industry, and also found in natural products. Compared to the alkenes attaching the directing groups or activating group, the catalytic asymmetric reaction of unactivated terminal alkenes presents great challenges due to the weak electron effect and small steric hindrance effect. This review mainly summerizes the latest progress of the asymmetric reaction of unactivated terminal olefins since 2016.
Monitoring of sweat pH play important roles in physiological health, nutritional balance, psychological stress, and sports performance. The combination of functional MOFs with phosphorescent material to acquire the real-time physiological information, as well as the ap-plication of dual mode anti-counterfeiting, have seldom been reported. Herein, we reported MOF and phosphorescent dyes based mul-tifunctional gel films with H+ response and the related mechanism was studied in detail. Upon induction of H+, the composite gel film ex-hibited decreased fluorescent signal but enhanced room temperature phosphorescence (RTP), which could be utilized for sweat pH sensing through a dual-mode. Moreover, multifunctional gel films exhibited a potential application in information encryption and an-ti-counterfeiting by designing of stimulus responsive multiple patterns. This research opens a new avenue for portable and non-invasive sweat pH monitoring method, provides opportunities for effective anti-counterfeiting, also offers new insights stimulus-responsive mul-tifunctional materials and their potential applications.
By employing the asymmetric end-group engineering, an asymmetric nonfused-ring electron acceptors (NFREAs) was designed and synthesized. Compared with the symmetric analogs (NoCA-17 and NoCA-18), NoCA-19 possesses broader light absorption range, more coplanar π-conjugated backbone, and appropriate crystallinity according to the experimental and theoretical results. The organic solar cells based on J52:NoCA-19 exhibited a power conversion efficiency as high as 12.26%, which is much higher than those of J52:NoCA-17 (9.50%) and J52:NoCA-18 (11.77%), mainly due to more efficient exciton dissociation, better and balanced charge mobility, suppressed recombination loss, shorter charge extraction time, longer charge carrier lifetimes, and more favorable blend film morphology. These findings demonstrate the great potential of asymmetric end-group engineering in exploring low-cost and high-performance NFREAs.
Carbon dioxide can be converted into functional heterocycles known as cyclic carbonates, whose recent reactivity has been expanded towards the formation of tailor-made engineering polymers. This minireview gives an overview of the most topical developments in this area with a special focus on the synthetic methods employed to prepare these CO2 based synthons. In addition, their application potential in the area of polymer science using a variety of polymerization techniques is discussed that have in common the ring-opening of the carbonate monomers. Future perspectives are provided that provide impetus for the scientific communities aligning research to the use of sustainable processes for polymers from recyclable carbon sources such as CO2.
Herein we report a condition-controlled divergent synthesis of spiro indene-2,1’-isoindolinones and spiro isochroman-3,1’-isoindolinones through cobalt-catalyzed formal [4 + 1] and [4 + 1 + 1] spirocyclization of aromatic amides with 2-diazo-1H-indene-1,3(2H)-dione. When the reaction is carried out under air in ethyl acetate, spiro indene-2,1’-isoindolinones are formed through Co(II)-catalyzed C−H/N−H [4 + 1] spirocyclization. When the reaction is run under O2 in CH3CN, on the other hand, spiro isochroman-3,1’-isoindolinones are generated through Baeyer-Villiger oxidation of the in situ formed spiro indene-2,1’-isoindolinones with O2 as a cheaper and environmental-friendly oxygen source. In general, these protocols have advantages such as using non-precious and earth-abundant metal catalyst, no extra additive, high efficiency and regioselectivity. A gram-scale synthesis and the removal of the directing group further highlight its utility.
A phosphine-catalyzed [4+3] annulation between dinucleophilic indole derivatives and Morita−Baylis−Hillman (MBH) carbonates was discovered by using the N1 and N4′ or C4′ nucleophilicities of indole precursors, which provides an efficient and facile access to in-dole-1,2-fused 1,4-diazepinones and azepines in good to high yields in one step, in which indoles act as four atom synthons. Various transformations of products illustrate promising applications of the given protocols.
Carbon monoxide (CO) has become one of the most relevant and versatile renewable C1 building blocks for chemical synthesis, especially in the fine chemicals industry, due to the development of efficient and selective catalysts for its activation. In this review, we present a comprehensive critical analysis of the last 10 years literature on the use of CO as a renewable feedstock for fine chemicals production. The review is organized by type of catalytic reaction, namely alkene and alkyne carbonylation, hydroformylation, carbonylation of aryl halides, carbonylative cross-coupling and C–H carbonylation. Notable examples of the synthesis of relevant building blocks and/or known pharmaceuticals are highlighted. Emphasis is placed on examples of utilizing CO as the C1 building block in one or more catalytic steps. The catalyst used and the reaction conditions are consistently presented throughout all of the examples.
Long-wavelength fluorescence of carbon dots (CDs) show the great importance in multiple fields, especially for the biochemical sensing. Here we proposed one type of CDs doped with nitrogen and sulfur through the hydrothermal method, which exhibited the obvious yel-low-fluorescence in aqueous. Importantly, their fluorescence intensity of CDs decreased with pH decreasing in the acidic range, thus a linear relationship between pH and fluorescence intensity was established, and exhibiting the potential of pH sensing. Additionally, in-troducing tigecycline into CDs resulted in their decreased fluorescence, thus we further established a strategy of detecting tigecycline with the concentration range of 200 μM to 7 nM. Meanwhile, we elucidated the static quenching as the major mechanism for CDs responding tigecycline, which was induced by the formed new complex between CDs and tigecycline. Furthermore, the practicality of the method was verified by examining the recovery of tigecycline in the actual lake-water samples.
Transition metal-catalyzed asymmetric transfer hydrogenation has been proved to be a powerful approach for the synthesis of chiral alcohols. Herein, A highly efficient and enantioselective transfer hydrogenation of dibenzoheptaheterocyclic ketones catalyzed by an arene-tethered TsDPEN-based Rh(III) catalyst has been successfully developed, and a variety of dibenzoheptaheterocyclic ketones were reduced by a 1/1 mixture of formic acid and DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) with high yields and enantioselectivities. With this method, the asymmetric reduction of 7,8-difluorodibenzo[b,e]thiepin-11(6H)-one has been realized, providing the key intermediate of baloxavir marboxil with >99% yield and >99% ee at a substrate/catalyst molar ratio of 1000.