Organofluorines play a crucial role in medicine,agrochemicals,and materials science.Adding fluorine to molecules creates structures with specific beneficial properties or tunes properties through interactions with the...Organofluorines play a crucial role in medicine,agrochemicals,and materials science.Adding fluorine to molecules creates structures with specific beneficial properties or tunes properties through interactions with their environment.Many popular pharmaceuticals and agrochemicals contain fluorine because it enhances hydrogen bonding at protein’s active sites.展开更多
Vicinal diamines are key motifs widely-found in many pharmaceuticals and biologically active molecules.An appealing approach for synthesizing these molecules is the amination of enamines,but few examples have been exp...Vicinal diamines are key motifs widely-found in many pharmaceuticals and biologically active molecules.An appealing approach for synthesizing these molecules is the amination of enamines,but few examples have been explored.With the utilization of nitrogen-centered radicals(NCRs),here we present the development of a dual bio-/photo-catalytic system for achieving enantioselective hydroamination of enamides,which can give easy access to diverse enantioenriched vicinal diamines.These reactions progress efficiently under green light excitation and exhibit excellent enantioselectivities(up to>99%enantiomeric excess).Mechanistic studies uncovered the synergistic effect of the enzyme and the externally added organophotoredox catalyst Rhodamine B(RhB).This work demonstrates the effectiveness of photobiocatalysis to generate and control high-energy radical intermediates,addressing a long-standing challenge in chemical synthesis.展开更多
Asymmetric reduction of ct-hydroxy aromatic ketones was carded out by using carrot enzymes system, yielding corresponding chiral vicinal diols with special functional groups. The optimum reaction conditions were obtai...Asymmetric reduction of ct-hydroxy aromatic ketones was carded out by using carrot enzymes system, yielding corresponding chiral vicinal diols with special functional groups. The optimum reaction conditions were obtained after investigation of various influencing factors. Chiral aryl vicinal diols were produced with good yields and excellent enantiomeric excesses under appropriate conditions. Meanwhile, the steric factors and electronic effects of the substituents on the aromatic ring were shown to have an interesting influence on both yield and enantioselectivity.展开更多
The vicinal dithiol motif is widely present in proteins, and is critical for proteins’ structures and functions.In recent years, a variety of fluorescent probes with high specificity and outstanding optical propertie...The vicinal dithiol motif is widely present in proteins, and is critical for proteins’ structures and functions.In recent years, a variety of fluorescent probes with high specificity and outstanding optical properties for sensing protein vicinal dithiols have been developed. In this review, we summarized the fluorescent probes of protein vicinal dithiols in literature. These probes are classified into four types based on their acceptor sites, i.e., biarsenical probes, monoarsenical probes, dimaleimide probes and diacrylate probes.Through analyzing the properties of different probes, we expect that this review would help readers further understand the structural factors of these probes and provide the design strategy for novel fluorescent probes with improved properties.展开更多
A practical synthesis of symmetrical vicinal diamines with broad chemistry scope is described. The key step is the ultrasonicwave promoted tandem-reaction, two-step reaction sequence combining Mannich double condensat...A practical synthesis of symmetrical vicinal diamines with broad chemistry scope is described. The key step is the ultrasonicwave promoted tandem-reaction, two-step reaction sequence combining Mannich double condensations with benzo- triazole, glyoxal and primary or secondary amines and reduction of the bis（benzotriazole）-adducts with sodium borohydride proceeded smoothly in tetrahydrofuran in high yield at room temperature.展开更多
Selective oxidation of glycerol provides a feasible route towards the sustainable synthesis of high value-added chemicals.Herein,the hydroxyapatite(HAP)supported palladium(Pd)species were fabricated by impregnation an...Selective oxidation of glycerol provides a feasible route towards the sustainable synthesis of high value-added chemicals.Herein,the hydroxyapatite(HAP)supported palladium(Pd)species were fabricated by impregnation and subsequent calcination.The as-obtained heterogeneous Pd catalyst afforded not only excellent selectivity to glyceric acid(GLA)up to 90%with 59%conversion of glycerol but also good recyclability by using molecular oxygen as an oxidant under mild conditions.The characterization of catalysts indicated that both the surface basicity and Pd sites on the catalyst played a crucial role in promoting glycerol oxidation.Notably,it demonstrated that the presence of the vicinal hydroxyl group of glycerol molecule can assist the oxidation reaction via forming a coordination between the vicinal hydroxyl group and Ca^(2+) sites on HAP-derived catalysts.In this catalytic process,the secondary hydroxyl of glycerol kept untouched and the primary hydroxyl of glycerol was converted into carboxyl group,while the Pd species acted as active centers for cooperatively promoting the subsequent oxidation to generate GLA.Additionally,this catalytic system can be extended widely for the oxidative conversion of other vicinal diols into the corresponding a-hydroxycarboxylic acids selectively.Isotope labeling experiment using H_(2)^(18)O confirmed that H_(2)O not only acted as solvent but also was involved in the catalytic cycles.On the basis of the results,a possible reaction mechanism has been proposed.The HAP-supported Pd catalytic system has been shown to serve as an effective approach for the upgrading of bio-derived vicinal diols to high value-added chemicals.展开更多
The AC bicyclic skeleton of daphniyunnine B with the required 3 stereocenters(C4,C5 and C8)was accomplished in a concise route which featured two Claisen-type rearrangement reactions to construct the required vicinal ...The AC bicyclic skeleton of daphniyunnine B with the required 3 stereocenters(C4,C5 and C8)was accomplished in a concise route which featured two Claisen-type rearrangement reactions to construct the required vicinal all carbon quaternary stereocenters(C5 and C8)and an intramolecular iodocyclization reaction to assemble the cis-confused bicyclic lactam.展开更多
A stereocontrolled construction of the side chain of brassinclide and homobrassinolide has been achieved via the tandem vicinal dialkylation of the pyranone moiety as a key step.
The ? ?vicinal dibromo carboxylic acid and its derivatives were debrominated with Sm/HOAc system to afford the corresponding cinnamic acid and its derivatives in good yields under mild conditions.
Enantiopure vicinal diols are important building blocks used in the synthesis of fine chemicals and pharmaceutical compounds. Diol dehydrogenase(DDH) mediated stereoselective oxidation of racemic vicinal is an efficie...Enantiopure vicinal diols are important building blocks used in the synthesis of fine chemicals and pharmaceutical compounds. Diol dehydrogenase(DDH) mediated stereoselective oxidation of racemic vicinal is an efficient way to prepare enantiopure vicinal diols. In this study, four new bacterial DDHs(AnDDH from Anoxybacillus sp. P3 H1 B, HcDDH from Hazenella coriacea, GzDDH from Geobacillus zalihae and LwDDH from Leptotrichia wadei) were mined from the GenBank database and expressed in E. coli T7.The four DDHs were purified and biochemically characterized for oxidation activity toward(R)-1-phenyl-1,2-ethanediol, with the optimal reaction condition of pH9.0(AnDDH), 10.0(HcDDH) and 11.0(GzDDH and LwDDH) and the temperatures at 40 ℃(AnDDH), 50 ℃(HcDDH) and 60 ℃(GzDDH and LwDDH), respectively. The four enzymes were stable at the pH from 7.0 to 9.0 and below 40 ℃.Kinetic parameters of four DDHs showed that the HcDDH from Hazenella coriacea had high activity toward a broad range of vicinal diols. A series of racemic vicinal diols were successfully resolved by recombinant E. coli(HcDDH-NOX) resting cells co-expression of an NADH oxidase(NOX), affording(S)-diols and(1 S, 2 S)-trans-diols in ≥99% ee. The synthetic potential of HcDDH was proved by E. coli(HcDDH-NOX) via kinetic resolution of racemic trans-1,2-indandiol on a 100 ml scale reaction,(S, S)-trans-1,2-indandiol was prepared in 46.7% yield and >99% ee. In addition, asymmetric reduction of four α-Hydroxy ketones(10–300 mmol·L^(-1)) by E. coli(HcDDH-GDH) resting cells resulted in >99% ee and69–98% yields of(R)-vicinal diols. The current research expands the toolbox of DDHs to synthesize chiral vicinal diols and demonstrated that the mined Hc DDH is a potential enzyme in the synthesis of a broad range of chiral vicinal diols.展开更多
A1GaN/GaN heterostructures on vicinal sapphire substrates and just-oriented sapphire substrates （0001） are grown by the metalorganic chemical vapor deposition method. Samples are studied by high-resolution x-ray dif...A1GaN/GaN heterostructures on vicinal sapphire substrates and just-oriented sapphire substrates （0001） are grown by the metalorganic chemical vapor deposition method. Samples are studied by high-resolution x-ray diffraction, atomic force microscopy, capacitance-voltage measurement and the Van der Panw Hall-effect technique. The investigation reveals that better crystal quality and surface morphology of the sample are obtained on the vicinal substrate. Fur- thermore, the electrical properties are also improved when the sample is grown on the vicinal substrate. This is due to the fact that the use of vicinal substrate can promote the step-flow mode of crystal growth, so many macro-steps are formed during crystal growth, which causes a reduction of threading dislocations in the crystal and an improvement in the electrical properties of the AlGaN/GaN heterostructure.展开更多
A novel strategy was developed for the asymmetric synthesis of fluorinated vicinal diamines.Deprotonation of N-(diphenylmethylene)-benzylamines under base,followed by asymmetric nucleophilic addition to N-tert-butanes...A novel strategy was developed for the asymmetric synthesis of fluorinated vicinal diamines.Deprotonation of N-(diphenylmethylene)-benzylamines under base,followed by asymmetric nucleophilic addition to N-tert-butanesulfinylfluoroacetaldimines,a pair of diastereomeric isomers were afforded.The diastereomeric isomers can be easily separated from each other by silica gel column chromatography.The absolute steric configuration of two isomers was confirmed by single crystal X-ray diffraction analyses.The proposed mechanism revealed that the configuration of the carbon next to tert-butanesulfinyl was well controlled to be R by the chiral auxiliary.展开更多
In the presence of equimolar triethylamine,vicinal dibromides were found to be easily debrominated by dibutyl telluride,forming the co- rresponding olefins.
Vicinal all-carbon quaternary stereocenters are widely present in natural products and bioactive molecules.However,the construction of such motif in one step from readily available starting materials remains a signifi...Vicinal all-carbon quaternary stereocenters are widely present in natural products and bioactive molecules.However,the construction of such motif in one step from readily available starting materials remains a significant challenge.Herein,we report a phosphine-catalyzed divergent γ,γ-and ε,γ-umpolung domino addition of bisoxindoles with allenoates.This method serves as a practical tool for the concise synthesis of a series of bisoxindole derivatives bearing sterically hindered vicinal all-carbon quaternary stereocenters under mild reaction conditions.The applicability of this novel method was demonstrated with the gram-scale synthesis of three known advanced intermediates for the total syntheses of calycanthine,chimonanthine and folicanthine.展开更多
An asymmetric catalytic strategy in photocatalysis utilizing a chirality-induced approach through an organocatalytic/photoredox relay catalysis strategy is successfully achieved for the rapid construction of polycycli...An asymmetric catalytic strategy in photocatalysis utilizing a chirality-induced approach through an organocatalytic/photoredox relay catalysis strategy is successfully achieved for the rapid construction of polycyclic compounds containing vicinal amino alcohols in a one-pot protocol. This methodology facilitates the efficient synthesis of diverse substituted polycyclic tetrahydroquinoline and benzofuran-derived vicinal amino alcohols, each containing five consecutive chiral centers, with high yields,excellent diastereoselectivities and enantioselectivities(up to 95% yield, >20:1 dr and 98% ee), under mild reaction conditions driven by sequential bifunctional squaramide organocatalyst-catalyzed [4+2] annulation and photocatalyst-catalyzed ketyl radical addition cyclization reaction process. Furthermore, investigations into the stereoselectivity mechanism and high-resolution mass spectrometry(HRMS) experiments on free radical trapping have provided evidence for elucidating the detailed mechanism of chirality-induced processes and chiral intermediate conversions in this procedure.展开更多
Vicinal stereogenic centers are ubiquitous structural scaffolds in both natural products and synthetic compounds,yet their enantioselective construction remains a significant challenge in organic synthesis.Organoboron...Vicinal stereogenic centers are ubiquitous structural scaffolds in both natural products and synthetic compounds,yet their enantioselective construction remains a significant challenge in organic synthesis.Organoboron compounds are of paramount importance in synthetic chemistry due to their ability to undergo facile transformations,yielding diverse essential chemical bonds such as carbon-carbon,carbon-oxygen,carbon-nitrogen,and carbon-halogen bonds.Transition-metal-catalyzed asymmetric borylative functionalizations of internal alkenes offer a promising strategy for the enantioselective installation of two adjacent chiral centers across carbon-carbon bonds.By leveraging the versatile transformations of the newly introduced boryl unit,this approach holds great potential for expanding the structural diversity of vicinal stereogenic scaffolds.In this concise review,we aim to highlight recent advancements in transition-metal-catalyzed asymmetric borylative functionalizations of internal alkenes,underscore their utility as a versatile approach for constructing vicinal stereogenic centers,and discuss unsolved challenges and future directions in this field.展开更多
We report the first highly diastereo-and enantioselective C-C bond-forming reaction of racemic α-branched ketones to construct tertiary alcohols with adjacent stereocenters.Accordingly,a highly stereoselective cyanos...We report the first highly diastereo-and enantioselective C-C bond-forming reaction of racemic α-branched ketones to construct tertiary alcohols with adjacent stereocenters.Accordingly,a highly stereoselective cyanosilylation of racemic ketones is developed using our bifunctional cyanating reagent,Me_(2)(CH_(2)Cl)SiCN,giving C^(α)-tetrasubstituted silyl cyanohydrins withtwovicinal stereocenters inupto>20:1 diastereomeric ratio(dr)and 90-98% enantiomeric excess(ee)values,which can undergo various diversification reactions bymanipulating the chloromethyl group.A highly selective kinetic resolution of acyclicα-branched ketones is also developed that allows facile access to acyclic α-alkyl,allyl,and propargyl ketones with good recovery and excellent ee values.The synthetic value of this protocol is further demonstrated by the formal synthesis of the anti-obesity agent,taranabant(MK-0364).The activation of Jacobsen’s privileged catalyst(salen)AlCl by a suitable phosphorane plays a crucial role in the reaction.X-ray crystallographic analysis of single crystals of phosphorane-(salen)AlCl complexes and theoretical calculations help provide a working model.The present transformation opens a new path for the catalytic stereoselective synthesis of stereochemically complex tertiary alcohols featuring two stereocenters(adjacent or not)from racemic ketones.展开更多
The Catellani reaction,originally discovered by Catellani in 1997,and further developed by Catellani,Lautens and others,has emerged as a powerful strategy for the synthesis of polysubstituted arenes,which would be dif...The Catellani reaction,originally discovered by Catellani in 1997,and further developed by Catellani,Lautens and others,has emerged as a powerful strategy for the synthesis of polysubstituted arenes,which would be difficult to access via traditional methods.In this process,both ortho-and/pso-positions of aryl halides could be functionalized simultaneously with different electrophiles and terminating agents under the cooperative catalysis of palladium and norbornene(NBE).This review focuses on the significant progress of such transformations,and the section of typical Catellani reactions is divided into five parts according to the functionalization mode of ortho-C-H bond:alkylation,arylation,amination,acylation or thiolation.展开更多
A series of new platinum（II） complexes with C2-asymmetric and C2-symmetric 1,2-diamines were designed and synthesized by convenient methods, involving samarium diiodide induced reductive coupling as the key step. Th...A series of new platinum（II） complexes with C2-asymmetric and C2-symmetric 1,2-diamines were designed and synthesized by convenient methods, involving samarium diiodide induced reductive coupling as the key step. The results of cytotoxicity showed that compounds （R,R）-lla and （S,S）-lla, two novel platinum（II） complexes with asymmetric 1,2-diamines, exhibited more potent cytotoxicity than that of oxaliplatin against all leukemia cell lines. Interestingly, （R,R）-lla and （S,S）-lla demonstrated less potent activity against three solid cancer cell lines than that of oxaliplatin, which indicated that these two compounds may only selectively inhibit the leukemia cell lines. In contrast, （R,R）-ISa and （S,S）-15a, two platinum（II） complexes with symmetric 1,2-diamines, showed similar cyto- toxicity to that of oxaliplatin against all leukemia cell lines and more potent activity against solid cancer cell lines. Further flow cytometry data indicated that （R,R）-lla could obviously arrest leukemia K562 cells in G2/M phases.展开更多
L1_(0)-FePt distinguishes itself for its ultrahigh perpendicular magnetic anisotropy(PMA),enabling thermally stabile memory cells to scale down to 3 nm.The recently discovered“bulk”spin−orbit torques in L1_(0)-FePt ...L1_(0)-FePt distinguishes itself for its ultrahigh perpendicular magnetic anisotropy(PMA),enabling thermally stabile memory cells to scale down to 3 nm.The recently discovered“bulk”spin−orbit torques in L1_(0)-FePt provide an efficient and scalable way to manipulate the L1_(0)-FePt magnetization.However,the existence of an external field during the switching limits its practical application,and therefore field-free switching of L1_(0)-FePt is highly demanded.In this manuscript,by growing the L1_(0)-FePt film on vicinal MgO(001)substrates,we realize the field-free switching of L1_(0)-FePt.This method is different from previously established strategies as it does not need to add other functional layers or create asymmetry in the film structure.The dependence on the vicinal angle,film thickness,and growth temperature demonstrates a wide operation window for the fieldfree switching of L1_(0)-FePt.We confirm the physical origin of the field-free switching is due to the tilted anisotropy of L1_(0)-FePt induced by the vicinal surface.We also quantitatively characterize the spin-orbit torques in the L1_(0)-FePt films.Our results extend beyond the established strategies to realize field-free switching,and potentially could be applied to mass production.展开更多
文摘Organofluorines play a crucial role in medicine,agrochemicals,and materials science.Adding fluorine to molecules creates structures with specific beneficial properties or tunes properties through interactions with their environment.Many popular pharmaceuticals and agrochemicals contain fluorine because it enhances hydrogen bonding at protein’s active sites.
文摘Vicinal diamines are key motifs widely-found in many pharmaceuticals and biologically active molecules.An appealing approach for synthesizing these molecules is the amination of enamines,but few examples have been explored.With the utilization of nitrogen-centered radicals(NCRs),here we present the development of a dual bio-/photo-catalytic system for achieving enantioselective hydroamination of enamides,which can give easy access to diverse enantioenriched vicinal diamines.These reactions progress efficiently under green light excitation and exhibit excellent enantioselectivities(up to>99%enantiomeric excess).Mechanistic studies uncovered the synergistic effect of the enzyme and the externally added organophotoredox catalyst Rhodamine B(RhB).This work demonstrates the effectiveness of photobiocatalysis to generate and control high-energy radical intermediates,addressing a long-standing challenge in chemical synthesis.
基金supported by the National Natural Science Foundation of China(No.21176203)the National Special Fund for State Key Laboratory of Bioreactor Engineering(No.2060204)the Fundamental Research Funds for the Central Universities(No.JUSRP211A12)
文摘Asymmetric reduction of ct-hydroxy aromatic ketones was carded out by using carrot enzymes system, yielding corresponding chiral vicinal diols with special functional groups. The optimum reaction conditions were obtained after investigation of various influencing factors. Chiral aryl vicinal diols were produced with good yields and excellent enantiomeric excesses under appropriate conditions. Meanwhile, the steric factors and electronic effects of the substituents on the aromatic ring were shown to have an interesting influence on both yield and enantioselectivity.
基金financial supports from the National Natural Science Foundation of China (Nos. 21572093 & 21778028)the 111 Project
文摘The vicinal dithiol motif is widely present in proteins, and is critical for proteins’ structures and functions.In recent years, a variety of fluorescent probes with high specificity and outstanding optical properties for sensing protein vicinal dithiols have been developed. In this review, we summarized the fluorescent probes of protein vicinal dithiols in literature. These probes are classified into four types based on their acceptor sites, i.e., biarsenical probes, monoarsenical probes, dimaleimide probes and diacrylate probes.Through analyzing the properties of different probes, we expect that this review would help readers further understand the structural factors of these probes and provide the design strategy for novel fluorescent probes with improved properties.
文摘A practical synthesis of symmetrical vicinal diamines with broad chemistry scope is described. The key step is the ultrasonicwave promoted tandem-reaction, two-step reaction sequence combining Mannich double condensations with benzo- triazole, glyoxal and primary or secondary amines and reduction of the bis（benzotriazole）-adducts with sodium borohydride proceeded smoothly in tetrahydrofuran in high yield at room temperature.
基金support from the National Natural Science Foundation of China(21773061,21978095)Innovation Program of Shanghai Municipal Education Commission(15ZZ031)the Fundamental Research Funds for the Central Universities。
文摘Selective oxidation of glycerol provides a feasible route towards the sustainable synthesis of high value-added chemicals.Herein,the hydroxyapatite(HAP)supported palladium(Pd)species were fabricated by impregnation and subsequent calcination.The as-obtained heterogeneous Pd catalyst afforded not only excellent selectivity to glyceric acid(GLA)up to 90%with 59%conversion of glycerol but also good recyclability by using molecular oxygen as an oxidant under mild conditions.The characterization of catalysts indicated that both the surface basicity and Pd sites on the catalyst played a crucial role in promoting glycerol oxidation.Notably,it demonstrated that the presence of the vicinal hydroxyl group of glycerol molecule can assist the oxidation reaction via forming a coordination between the vicinal hydroxyl group and Ca^(2+) sites on HAP-derived catalysts.In this catalytic process,the secondary hydroxyl of glycerol kept untouched and the primary hydroxyl of glycerol was converted into carboxyl group,while the Pd species acted as active centers for cooperatively promoting the subsequent oxidation to generate GLA.Additionally,this catalytic system can be extended widely for the oxidative conversion of other vicinal diols into the corresponding a-hydroxycarboxylic acids selectively.Isotope labeling experiment using H_(2)^(18)O confirmed that H_(2)O not only acted as solvent but also was involved in the catalytic cycles.On the basis of the results,a possible reaction mechanism has been proposed.The HAP-supported Pd catalytic system has been shown to serve as an effective approach for the upgrading of bio-derived vicinal diols to high value-added chemicals.
基金financial support from the National Natural Science Foundation of China (Nos. 21102062, 21472079)
文摘The AC bicyclic skeleton of daphniyunnine B with the required 3 stereocenters(C4,C5 and C8)was accomplished in a concise route which featured two Claisen-type rearrangement reactions to construct the required vicinal all carbon quaternary stereocenters(C5 and C8)and an intramolecular iodocyclization reaction to assemble the cis-confused bicyclic lactam.
文摘A stereocontrolled construction of the side chain of brassinclide and homobrassinolide has been achieved via the tandem vicinal dialkylation of the pyranone moiety as a key step.
基金Project supported by the National Natural Science Foundation of China(No.29872010)the Natural Science Foundation of Zhejiang Province(No.298067)
文摘The ? ?vicinal dibromo carboxylic acid and its derivatives were debrominated with Sm/HOAc system to afford the corresponding cinnamic acid and its derivatives in good yields under mild conditions.
基金supported by the National Natural Science Foundation of China(Grant No.21772141)the Shanxi Province Science Foundation for Youths(grant No.201701D221042)the Key Research and Development(R&D)Project of Shanxi Province(201803D31050).
文摘Enantiopure vicinal diols are important building blocks used in the synthesis of fine chemicals and pharmaceutical compounds. Diol dehydrogenase(DDH) mediated stereoselective oxidation of racemic vicinal is an efficient way to prepare enantiopure vicinal diols. In this study, four new bacterial DDHs(AnDDH from Anoxybacillus sp. P3 H1 B, HcDDH from Hazenella coriacea, GzDDH from Geobacillus zalihae and LwDDH from Leptotrichia wadei) were mined from the GenBank database and expressed in E. coli T7.The four DDHs were purified and biochemically characterized for oxidation activity toward(R)-1-phenyl-1,2-ethanediol, with the optimal reaction condition of pH9.0(AnDDH), 10.0(HcDDH) and 11.0(GzDDH and LwDDH) and the temperatures at 40 ℃(AnDDH), 50 ℃(HcDDH) and 60 ℃(GzDDH and LwDDH), respectively. The four enzymes were stable at the pH from 7.0 to 9.0 and below 40 ℃.Kinetic parameters of four DDHs showed that the HcDDH from Hazenella coriacea had high activity toward a broad range of vicinal diols. A series of racemic vicinal diols were successfully resolved by recombinant E. coli(HcDDH-NOX) resting cells co-expression of an NADH oxidase(NOX), affording(S)-diols and(1 S, 2 S)-trans-diols in ≥99% ee. The synthetic potential of HcDDH was proved by E. coli(HcDDH-NOX) via kinetic resolution of racemic trans-1,2-indandiol on a 100 ml scale reaction,(S, S)-trans-1,2-indandiol was prepared in 46.7% yield and >99% ee. In addition, asymmetric reduction of four α-Hydroxy ketones(10–300 mmol·L^(-1)) by E. coli(HcDDH-GDH) resting cells resulted in >99% ee and69–98% yields of(R)-vicinal diols. The current research expands the toolbox of DDHs to synthesize chiral vicinal diols and demonstrated that the mined Hc DDH is a potential enzyme in the synthesis of a broad range of chiral vicinal diols.
基金Project supported by the State Key Program of National Natural Science Foundation of China (Grant No 60736033)the National Key Science and Technology Special Project (Grant No 2008ZX 0101002-003)
文摘A1GaN/GaN heterostructures on vicinal sapphire substrates and just-oriented sapphire substrates （0001） are grown by the metalorganic chemical vapor deposition method. Samples are studied by high-resolution x-ray diffraction, atomic force microscopy, capacitance-voltage measurement and the Van der Panw Hall-effect technique. The investigation reveals that better crystal quality and surface morphology of the sample are obtained on the vicinal substrate. Fur- thermore, the electrical properties are also improved when the sample is grown on the vicinal substrate. This is due to the fact that the use of vicinal substrate can promote the step-flow mode of crystal growth, so many macro-steps are formed during crystal growth, which causes a reduction of threading dislocations in the crystal and an improvement in the electrical properties of the AlGaN/GaN heterostructure.
基金the Innovation Program of Shanghai Municipal Education Commission,China(No.13ZZ047)the Fundamental Research Funds for the Central Universities,China(No.2232015D3-13)
文摘A novel strategy was developed for the asymmetric synthesis of fluorinated vicinal diamines.Deprotonation of N-(diphenylmethylene)-benzylamines under base,followed by asymmetric nucleophilic addition to N-tert-butanesulfinylfluoroacetaldimines,a pair of diastereomeric isomers were afforded.The diastereomeric isomers can be easily separated from each other by silica gel column chromatography.The absolute steric configuration of two isomers was confirmed by single crystal X-ray diffraction analyses.The proposed mechanism revealed that the configuration of the carbon next to tert-butanesulfinyl was well controlled to be R by the chiral auxiliary.
文摘In the presence of equimolar triethylamine,vicinal dibromides were found to be easily debrominated by dibutyl telluride,forming the co- rresponding olefins.
基金the financial support provided by the National Natural Science Foundation of China(22207063),111 Project(D20015)the Natural Science Research Project of Yichang City(A23-2-002)the Opening Funding of Hubei Key Laboratory of Natural Products Research and Development,China Three Gorges University(2024NPRD03,2024NPRD04,2024NPRD05).
文摘Vicinal all-carbon quaternary stereocenters are widely present in natural products and bioactive molecules.However,the construction of such motif in one step from readily available starting materials remains a significant challenge.Herein,we report a phosphine-catalyzed divergent γ,γ-and ε,γ-umpolung domino addition of bisoxindoles with allenoates.This method serves as a practical tool for the concise synthesis of a series of bisoxindole derivatives bearing sterically hindered vicinal all-carbon quaternary stereocenters under mild reaction conditions.The applicability of this novel method was demonstrated with the gram-scale synthesis of three known advanced intermediates for the total syntheses of calycanthine,chimonanthine and folicanthine.
基金supported by the National Natural Science Foundation of China(21632003,21871116,22071085,U22A20390)the Fundamental Research Funds for the Central Universities(lzujbky-2023-stlt01)the 111 Program from the Ministry of Education of China。
文摘An asymmetric catalytic strategy in photocatalysis utilizing a chirality-induced approach through an organocatalytic/photoredox relay catalysis strategy is successfully achieved for the rapid construction of polycyclic compounds containing vicinal amino alcohols in a one-pot protocol. This methodology facilitates the efficient synthesis of diverse substituted polycyclic tetrahydroquinoline and benzofuran-derived vicinal amino alcohols, each containing five consecutive chiral centers, with high yields,excellent diastereoselectivities and enantioselectivities(up to 95% yield, >20:1 dr and 98% ee), under mild reaction conditions driven by sequential bifunctional squaramide organocatalyst-catalyzed [4+2] annulation and photocatalyst-catalyzed ketyl radical addition cyclization reaction process. Furthermore, investigations into the stereoselectivity mechanism and high-resolution mass spectrometry(HRMS) experiments on free radical trapping have provided evidence for elucidating the detailed mechanism of chirality-induced processes and chiral intermediate conversions in this procedure.
基金National Natural Science Foundation of China(22271161,22188101)the Tianjin Science Fund for Distinguished Young Scholars(23JCJQJC00180)+1 种基金the Fundamental Research Funds for the Central Universities(63233165,63243134)Nankai University,for financial support.
文摘Vicinal stereogenic centers are ubiquitous structural scaffolds in both natural products and synthetic compounds,yet their enantioselective construction remains a significant challenge in organic synthesis.Organoboron compounds are of paramount importance in synthetic chemistry due to their ability to undergo facile transformations,yielding diverse essential chemical bonds such as carbon-carbon,carbon-oxygen,carbon-nitrogen,and carbon-halogen bonds.Transition-metal-catalyzed asymmetric borylative functionalizations of internal alkenes offer a promising strategy for the enantioselective installation of two adjacent chiral centers across carbon-carbon bonds.By leveraging the versatile transformations of the newly introduced boryl unit,this approach holds great potential for expanding the structural diversity of vicinal stereogenic scaffolds.In this concise review,we aim to highlight recent advancements in transition-metal-catalyzed asymmetric borylative functionalizations of internal alkenes,underscore their utility as a versatile approach for constructing vicinal stereogenic centers,and discuss unsolved challenges and future directions in this field.
基金supported by the National Natural Science Foundation of China(grant no.21725203)the Ministry of Education(PCSIRT)The Fundamental Research Funds for the Central Universities is highly appreciated.
文摘We report the first highly diastereo-and enantioselective C-C bond-forming reaction of racemic α-branched ketones to construct tertiary alcohols with adjacent stereocenters.Accordingly,a highly stereoselective cyanosilylation of racemic ketones is developed using our bifunctional cyanating reagent,Me_(2)(CH_(2)Cl)SiCN,giving C^(α)-tetrasubstituted silyl cyanohydrins withtwovicinal stereocenters inupto>20:1 diastereomeric ratio(dr)and 90-98% enantiomeric excess(ee)values,which can undergo various diversification reactions bymanipulating the chloromethyl group.A highly selective kinetic resolution of acyclicα-branched ketones is also developed that allows facile access to acyclic α-alkyl,allyl,and propargyl ketones with good recovery and excellent ee values.The synthetic value of this protocol is further demonstrated by the formal synthesis of the anti-obesity agent,taranabant(MK-0364).The activation of Jacobsen’s privileged catalyst(salen)AlCl by a suitable phosphorane plays a crucial role in the reaction.X-ray crystallographic analysis of single crystals of phosphorane-(salen)AlCl complexes and theoretical calculations help provide a working model.The present transformation opens a new path for the catalytic stereoselective synthesis of stereochemically complex tertiary alcohols featuring two stereocenters(adjacent or not)from racemic ketones.
基金the National Natural Science Foundation of China(21925108,21672169)the Key Science and Technology Innovation Team of Shaanxi Province(2017KCT-37)the Key Laboratory Project of Xi'an(201805058ZD9CG42)for financial support.
文摘The Catellani reaction,originally discovered by Catellani in 1997,and further developed by Catellani,Lautens and others,has emerged as a powerful strategy for the synthesis of polysubstituted arenes,which would be difficult to access via traditional methods.In this process,both ortho-and/pso-positions of aryl halides could be functionalized simultaneously with different electrophiles and terminating agents under the cooperative catalysis of palladium and norbornene(NBE).This review focuses on the significant progress of such transformations,and the section of typical Catellani reactions is divided into five parts according to the functionalization mode of ortho-C-H bond:alkylation,arylation,amination,acylation or thiolation.
基金Acknowledgement Financial support by the National Natural Science Foundation of China （No. 81172920）, the Shanghai Municipal Committee of Science and Technology （No. 10431903100）, and the National Basic Research Pro- gram of China （973 Program, No. 2010CB912603） are acknowledged. We would like to thank Prof. G.-Q. Lin for the guidance of asymmetric synthesis.
文摘A series of new platinum（II） complexes with C2-asymmetric and C2-symmetric 1,2-diamines were designed and synthesized by convenient methods, involving samarium diiodide induced reductive coupling as the key step. The results of cytotoxicity showed that compounds （R,R）-lla and （S,S）-lla, two novel platinum（II） complexes with asymmetric 1,2-diamines, exhibited more potent cytotoxicity than that of oxaliplatin against all leukemia cell lines. Interestingly, （R,R）-lla and （S,S）-lla demonstrated less potent activity against three solid cancer cell lines than that of oxaliplatin, which indicated that these two compounds may only selectively inhibit the leukemia cell lines. In contrast, （R,R）-ISa and （S,S）-15a, two platinum（II） complexes with symmetric 1,2-diamines, showed similar cyto- toxicity to that of oxaliplatin against all leukemia cell lines and more potent activity against solid cancer cell lines. Further flow cytometry data indicated that （R,R）-lla could obviously arrest leukemia K562 cells in G2/M phases.
基金This work was supported by the“Pioneer”and“Leading Goose”RD Program of Zhejiang Province(Grant No.2022C01053)the National Natural Science Foundation of China(Grant No.12274108,11874135 and 12104119)+1 种基金the Key Research and Development Program of Zhejiang Province(Grant No.2021C01039)the Natural Science Foundation of Zhejiang Province,China(Grant Nos.LQ20F040005 and LQ21A050001).
文摘L1_(0)-FePt distinguishes itself for its ultrahigh perpendicular magnetic anisotropy(PMA),enabling thermally stabile memory cells to scale down to 3 nm.The recently discovered“bulk”spin−orbit torques in L1_(0)-FePt provide an efficient and scalable way to manipulate the L1_(0)-FePt magnetization.However,the existence of an external field during the switching limits its practical application,and therefore field-free switching of L1_(0)-FePt is highly demanded.In this manuscript,by growing the L1_(0)-FePt film on vicinal MgO(001)substrates,we realize the field-free switching of L1_(0)-FePt.This method is different from previously established strategies as it does not need to add other functional layers or create asymmetry in the film structure.The dependence on the vicinal angle,film thickness,and growth temperature demonstrates a wide operation window for the fieldfree switching of L1_(0)-FePt.We confirm the physical origin of the field-free switching is due to the tilted anisotropy of L1_(0)-FePt induced by the vicinal surface.We also quantitatively characterize the spin-orbit torques in the L1_(0)-FePt films.Our results extend beyond the established strategies to realize field-free switching,and potentially could be applied to mass production.
