Herein we report an asymmetric two-component alkenyl Catellani reaction for the construction of C–N axial chirality through a pal-ladium/chiral norbornene cooperative catalysis and an axial-to-axial chirality transfer process. Various partially aromatic iodinated 2-pyridones, quinolones, coumarin and uracil substrates react with 2,6-disubstituted aryl bromides with a tethered amide group, to afford a wide variety of polycyclic C–N atropisomers (38 examples, up to 97% e.e.). The obtained C–N axial chirality is originated from the preformed transient C–C axial chirality with high fidelity. The synthetic utility of this chemistry is demonstrated by facile preparation of complex quinoline and pyridine based C–N atropisomers through a N-deprotection and aromatization sequence. In addition, a remote axial-to-central diastereoinduction process dictated by C–N axial chirality is observed with excellent diastere-ocontrol.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Furans bearing alkynyl substituents are highly useful in organic synthesis. However, the methodologies to access these important furan derivatives are rather limited. We herein report an efficient synthesis of alkynylated furan derivatives based on Pd-catalyzed oxidative cross-coupling reaction between allenyl ketones and terminal alkynes. This novel synthesis of alkynylated furans with wide substrate scope is operationally simple and tolerates various functional groups. Mechanistically, the formation of the palladium carbene through cycloisomerization and the subsequent alkynyl migratory insertion are proposed as the key steps in the transformation. The reaction reported in this manuscript further demonstrates the generality of the carbene-based cross coupling.
Here, we report a cobalt-catalyzed sequential dehydrogenative Heck silylation/hydroamination of styrenes with hydrosilane and diazo compound to access 1-amino-2-silyl compounds with excellent regioselectivity. This difunctionalization reaction could undergo smoothly using 1 mol% catalyst loading with good functional group tolerance. Not only di- and tri-substituted hydrosilanes, but also alkoxysilane are suitable, which does explore the scope of the family of 1-amino-2-silyl compounds. The ligand relay phenomenon between neutral tridentate NNN ligand and anionic NNN ligand is observed for the first time via absorption spectra analysis in this one-pot, two-step transformations. The primary mechanism has been proposed based on the control experiments.
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 one-pot synthesis of vicinal diamines using indoles, pyrazoles, and phenothiazines in a tandem multi-component reaction is developed. The utilization of a copper-iodine co-catalytic system enables the generation of a diverse range of vicinal diaminoindoles with good selectivity and moderate to good yields. An attractive aspect of this method is that it can be conducted under mild and environmentally friendly conditions, showcasing its potential as an alternative approach for synthesizing vicinal diamines. Moreover, the use of a multicomponent tandem reaction highlights the power and versatility of such strategies in synthetic chemistry.
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.
Polycyclic N-heterocycles are very important scaffolds in biomedicinal chemistry and materials science. Intramolecular alkyne hy-droamination is a powerful method for the construction of N-heterocycles. In the last two decades, copper-catalyzed domino reac-tions based on intramolecular alkyne hydroamination has emerged as a robust strategy for assembling various polycyclic N-heterocycles. Great progress has been achieved in this area. This short review covers the advances made in copper-catalyzed domino synthesis of polycyclic N-heterocycles based on this strategy from 2008 to 2023, and will hopefully serve as an inspiration towards the exploration of new copper-catalyzed versions of the transformation. The domino transformations are introduced and discussed from five aspects according to the different key processes involved in these reactions.
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.