Enones are widely explored in synthetic chemistry as fundamental building blocks for a wide range of reactions and exhibit intriguing biological activities that are pivotal for drug discovery.The development of synthe...Enones are widely explored in synthetic chemistry as fundamental building blocks for a wide range of reactions and exhibit intriguing biological activities that are pivotal for drug discovery.The development of synthetic strategies for highly efficient preparation of enones thereby receives intense attention,in particular through the transition metal-catalyzed coupling reactions.Here,we describe a carbene-catalyzed cross dehydrogenative coupling(CDC)reaction that enables effective assembly of simple aldehydes and alkenes to afford a diverse set of enone derivatives.Mechanistically,the in situ generated aryl radical is pivotal to“activate”the alkene by forming an allyl radical through intermolecular hydrogen atom transfer(HAT)pathway and thus forging the carbon-carbon bond formation with aldehyde as the acyl synthon.Notably,our method represents the first example on the enone synthesis through coupling of“non-functionalized”aldehydes and alkenes as coupling partners,and offers a distinct organocatalytic pathway to the transition metal-catalyzed coupling transformations.展开更多
Ni(0)-catalyzed regio-and diastereodivergent[4+2]annulation of biphenylenes withα,βunsaturated ketones is described.This solvent-controlled diastereodivergent reaction integrates C-C bond cleavage of biphenylene and...Ni(0)-catalyzed regio-and diastereodivergent[4+2]annulation of biphenylenes withα,βunsaturated ketones is described.This solvent-controlled diastereodivergent reaction integrates C-C bond cleavage of biphenylene and C=C double bond insertion selectivity,offering a mild approach to all possible diastereoisomers of 9,10-dihydrophenanthrene derivatives from the same starting materials.展开更多
A series of novel chiral diphosphite ligands have been synthesized from（1R,2R）-trans-1,2-cyclohexanediol,（1S,2S）-trans-1,2-cyclohexanediol, racemic trans-1,2-cyclohexanediol and chlorophosphoric acid diary ester, ...A series of novel chiral diphosphite ligands have been synthesized from（1R,2R）-trans-1,2-cyclohexanediol,（1S,2S）-trans-1,2-cyclohexanediol, racemic trans-1,2-cyclohexanediol and chlorophosphoric acid diary ester, and were successfully employed in the Cu-catalyzed asymmetric 1,4-conjugate addition of diethylzinc to cyclohexenone with up to 99% ee. It was found that ligand 1,2-bis[（R）-1,10-binaphthyl-2,2＇-diyl]phosphitecyclohexanediol 6a derived from racemic diol skeleton can show similar catalytic performance compared with ligand（1R,2R）-bis[（R）-1,1＇-binaphthyl-2,2＇-diyl]phosphitecyclohexanediol 6a＇ derived from enantiopure starting material. A significant dependence of stereoselectivity on the type of enone and the ring size of the cyclic enone was observed. Moreover, the configuration of the products was mainly determined by the configuration of the binaphthyl moieties of diphosphite ligands in the 1,4-addition of cyclic enones.展开更多
The asymmetric conjugate additions of aryl Grignard reagents to trisubstituted enones by chiral P,N ligand L6 with low catalyst loading(0.25–1.0 mol%)are disclosed.Chiral 2-ester chromanone and its analogs bearing a ...The asymmetric conjugate additions of aryl Grignard reagents to trisubstituted enones by chiral P,N ligand L6 with low catalyst loading(0.25–1.0 mol%)are disclosed.Chiral 2-ester chromanone and its analogs bearing a quaternary stereogenic centers at C2 position were produced in high to excellent yields,enantioselectivities and high turnover number.The notable features of this reaction include its broad substrate scope,complete 1,4-addition regioselectivities,applicability to both batch and flow for large scale synthesis.This report develops an efficient strategy to apply aryl Grignard reagents in asymmetric 1,4-conjugation reactions and provides a direct method to incorporate quaternary chiral centers toward the synthesis of biologically relevant chromanone derivatives.展开更多
The efficient construction of functionalized polycyclic structures is an imports nt objective in organic synthesis.Herein,we disclose a three-step"[2+n]"annulation method for the transformation of cyclic ket...The efficient construction of functionalized polycyclic structures is an imports nt objective in organic synthesis.Herein,we disclose a three-step"[2+n]"annulation method for the transformation of cyclic ketones to fused enimines and enones.The method relies on the Suzuki coupling reaction and the amide reductive alkenylation reaction.A series of fused bicyclic(6/6,6/7,8/7)and tricyclic(6/6/6;6/6/7,6/5/7)ring systems bearing an α,β-enimine or an α,β-enone functionality have been synthetized in good overall yields.展开更多
Alkaloids are one of the prominent members in the development of new antimicrobial agents.This work discovered a class of alkaloid quinazolone-derived imidazolenones as novel structural type of antibacterial agents wi...Alkaloids are one of the prominent members in the development of new antimicrobial agents.This work discovered a class of alkaloid quinazolone-derived imidazolenones as novel structural type of antibacterial agents with large potential to treat severe bacterial infections in the agricultural and food field.Preliminary bioactive assay displayed that some of the prepared compounds exhibited good inhibition against the tested strains,and cyclohexylimidazole-derived 7-fluoroquinazolone 22a(MIC=0.002 mmol/L)exhibited a 12.5-fold stronger inhibition than norfloxacin against Escherichia coli ATCC 25922.Further studies revealed that compound 22a not only possessed the ability of rapid bactericidal property and low propensity to develop resistance but also showed low cytotoxic effects toward red blood cells.The preliminary mechanism exploration indicated that compound 22a could cause membrane damage by disrupting bacterial membrane as well as depolarizing the cell membrane.Moreover,compound 22a could insert into DNA,which might hinder the replication of DNA.Molecular docking suggested that compound 22a could bind to gyrase and topoisomerase,which might be due to the suppressed expression of related genes.Meanwhile,compound 22a could disorder the metabolism and stimulate the production of reactive oxygen species to affect bacterial growth.The series of investigations suggested the promise of alkaloid quinazolone-derived imidazolenones as novel multitargeting antibacterial candidates for treatment of bacterial infections.展开更多
Main observation and conclusion The enantioselective hydrogenation of endocyclic enones has been a historical problem for homogeneous catalysis.We herein report an efficient method to reduce endocyclic enones with mol...Main observation and conclusion The enantioselective hydrogenation of endocyclic enones has been a historical problem for homogeneous catalysis.We herein report an efficient method to reduce endocyclic enones with molecular hydrogen.Catalyzed by a rhodium/Zhaophos complex,a variety of enones with five-,six-or seven-member ring were hydrogenated with high enantioselectivity(92%-99%ee).Excellent chemo-and enantioselectivity demonstrated this method was successfully applied in the enantioselective hydrogenation of citral to produce enantio-enriched citronellal.展开更多
A convergent approach to 1,5-hydroxy ketones,the general precursors for constructing the C ring of bryostatins,has been developed via a Zn/Cu-promoted conjugate addition of a-hydroxy iodides with enones.The reaction l...A convergent approach to 1,5-hydroxy ketones,the general precursors for constructing the C ring of bryostatins,has been developed via a Zn/Cu-promoted conjugate addition of a-hydroxy iodides with enones.The reaction leads to direct formation of the C21-C22 bond and tolerates diverse functionalities at the C17-,C18-and C24-positions.The approach also enables a more concise synthesis of the known C ring intermediate(10 longest linear steps and 14 total steps),in contrast to its previous synthesis(17 longest linear steps and 22 total steps) in our total synthesis of bryostatin 8.展开更多
The nucleophilic addition of Ti(IV) enolate derived from methyl aryl ketones to α, β–unsaturated compounds was found to be highly selective to give 1, 2 addition products.
A new enone (CH 3CO C( p NO 2C 6H 4COO)=CH S C 6H 4( p Br) 5, C 17 H 12 NBrO 5S, M r =422.25) was synthesized and its crystal structure was determined by X ray diffraction method. The crystal belongs to the monoclinic...A new enone (CH 3CO C( p NO 2C 6H 4COO)=CH S C 6H 4( p Br) 5, C 17 H 12 NBrO 5S, M r =422.25) was synthesized and its crystal structure was determined by X ray diffraction method. The crystal belongs to the monoclinic system, space group P2 1/c with a=6.4121(9), b=12.804(1), c=20.998(2) , β=94.884(9)°, V=1717.1(3) 3, Z=4, D c =1.633 g/cm 3, μ (Mo Kα )=2.542 mm -1 , F( 000)=848. Final R =0.0428 and wR =0.0916 for 3335 reflections with I>2σ(I) . The title compound exists as Z isomer with p bromothiophenolate and o nitrobenzoate groups cis arranged around asymmetrical centre. This observation suggests that the substitution of thiophenolate for bromine is a stereoselective step.展开更多
The first intermolecular electrophilic dearomatization of halonaphthols with benzyl/allyl bromides is described. Halonaphthols are used as carbon-nucleophiles in dearomatization to form three-dimensional cyclic enones...The first intermolecular electrophilic dearomatization of halonaphthols with benzyl/allyl bromides is described. Halonaphthols are used as carbon-nucleophiles in dearomatization to form three-dimensional cyclic enones with excellent chemoselectivity, in which etherification of phenolic hydroxyl group could be restrained well by using cesium carbonate as the base. A wide range of cyclic enones is directly prepared from various substituted benzyl/allyl bromides and halonaphthols. Mechanistic investigations suggest a direct S_(N)2 reaction pathway.展开更多
Deconjugation of cyclopent-2-enone aldols were attempted under various conditions, and the desired deconjugated product was achieved via dianion approach. Various results obtained in this study are explained by struct...Deconjugation of cyclopent-2-enone aldols were attempted under various conditions, and the desired deconjugated product was achieved via dianion approach. Various results obtained in this study are explained by structure and transition state analysis.展开更多
NTrifluoromethyl and cyclopropyl substituted 2-isoxazolines were synthesized via a DBU-promoted domino reaction of β-trifluoromethyl-/β-cyclopropyl-substituted enones with hydroxylamine. The domino reaction consists...NTrifluoromethyl and cyclopropyl substituted 2-isoxazolines were synthesized via a DBU-promoted domino reaction of β-trifluoromethyl-/β-cyclopropyl-substituted enones with hydroxylamine. The domino reaction consists of a Michael addition and the followed cyclization. A wide range of 3-substituted 5-cyclopropyl-5-trifluoromethyl-2-isoxazolines were obtained in good to excellent yields under mild reaction conditions. The method could also apply to other trifluoromethyl-substituted enones.展开更多
A catalyst-free and additive-free ring-opening reaction of polyfluoroalkyl peroxides,triethylenediamine(DABCO),and 1,2-dichloroethane(DCE)has been developed for the defluorinative synthesis of structurally diverse pip...A catalyst-free and additive-free ring-opening reaction of polyfluoroalkyl peroxides,triethylenediamine(DABCO),and 1,2-dichloroethane(DCE)has been developed for the defluorinative synthesis of structurally diverse piperazines featuring a fluoroenone framework and a N-chloroethyl-substituent with high Z-stereoselectivity.The success of this three-component reaction is attributed to the in situ generation of an active 1-(2-chloroethyl)-1,4-diazabicyclo[2.2.2]octan-1-ium(DABCO·DCE)salt,which judiciously acts as a formal N-(2-chloroethyl)piperazine equivalent in the defluorinative coupling with less-studied aliphatic fluorinated substances.Impressively,this reaction accomplishes multi-activation of robust C(sp^(3))-F,C(sp^(3))-Cl,C(sp^(3))-O,and C(sp^(3))-N bonds in a one-pot process,offering a practical platform for the late-stage functionalization of complex molecules.Furthermore,the resulting products can not only serve as versatile building blocks for the synthesis of fluorinated heterocycles,but also undergo C—Cl bond displacement transformations with N-,O-,and S-nucleophiles.展开更多
Catalytic dehydrogenation,with its exceptional atom economy and chemoselectivity,offers a highly desirable yet challenging approach for converting multiple environmentally friendly alcohols into crucial molecules.Furt...Catalytic dehydrogenation,with its exceptional atom economy and chemoselectivity,offers a highly desirable yet challenging approach for converting multiple environmentally friendly alcohols into crucial molecules.Furthermore,the utilization of catalysts based on abundant elements found on Earth for alcohol dehydrogenation to produce acryl ketone holds significant promise as a versatile strategy in synthesizing key building blocks for numerous pharmaceutical applications.The present study describes a practical Co-catalyzed cascade dehydrogenative Claisen condensation of secondary alcohols with esters,facilitating the synthesis of a wide range of 3-hydroxy-prop-2-en-1-ones.We introduce a catalytic system based on novel and scalable indazole NNP-ligands coordinated to cobalt for efficient dehydrogenations of secondary alcohols,and propose a plausible reaction mechanism supported by control experiments and labeling studies.Notably,it allows for the streamlined synthesis of multiple pharmaceuticals in one-pot.展开更多
b Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, China One pot hydroiodination and deconjugation of 5 aryloxy(or thiophenyl) 3 pentyn 2 one with a reagent system of sodium iodide/trimethylsily...b Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, China One pot hydroiodination and deconjugation of 5 aryloxy(or thiophenyl) 3 pentyn 2 one with a reagent system of sodium iodide/trimethylsilyl chloride/water in acetonitrile at 25 ℃ have been described. The plausible mechanism was discussed. The reaction provided a simple and useful method for the preparation of ( Z ) β substituted β,γ enones and ( Z ) β substituted α,β unsaturated ketones.展开更多
A highly enantioselective 1,3-dipolar cycloaddition ofα-substituted diazoesters with exocyclic enones was achieved with chiral scandium(III)/N,N’-dioxide complex as the catalyst.This protocol provided a facile and e...A highly enantioselective 1,3-dipolar cycloaddition ofα-substituted diazoesters with exocyclic enones was achieved with chiral scandium(III)/N,N’-dioxide complex as the catalyst.This protocol provided a facile and efficient route to optically active 1-pyrazoline-based spirochromanones and others with good outcomes(up to 97%yield,98%ee with>95:5 dr).Moreover,enantioenriched 2-pyrazoline-based spirochromanones were also accessible by switchingα-substituted diazoesters toα-diazoacetates.The further specific transformations of chiral pyrazoline-based spiro-compounds to spirocyclopropane derivatives were disclosed as well.展开更多
The ethylene ketal of 2-cyelopentenone and 2-cyelohexenone in acetonitrile in the presence of a trace of an acid rapidly undergoes the Diels-Alder type dimerization,The products are regiospecific but not stereoselecti...The ethylene ketal of 2-cyelopentenone and 2-cyelohexenone in acetonitrile in the presence of a trace of an acid rapidly undergoes the Diels-Alder type dimerization,The products are regiospecific but not stereoselective and are hydrolysed sequentially to afford keto-ketals and diketones whose structures are determined by extensive applications of NMR spectroscopy.展开更多
基金funding supports from the National Natural Science Foundation of China(Nos.21732002,22061007,22071036,and 22207022)Frontiers Science Center for Asymmetric Synthesis and Medicinal Molecules,National Natural Science Fund for Excellent Young Scientists Fund Program(Overseas),the starting grant of Guizhou University[No.(2022)47)]+10 种基金Department of Education,Guizhou Province[Qianjiaohe KY No.(2020)004]The 10 Talent Plan(Shicengci)of Guizhou Province(No.[2016]5649)Science and Technology Department of Guizhou Province(Nos.[Qiankehe-jichu-ZK[2022]zhongdian024],[2018]2802,[2019]1020,QKHJC-ZK[2022]-455)Department of Education of Guizhou Province(No.QJJ(2022)205)Program of Introducing Talents of Discipline to Universities of China(111 Program,No.D20023)at Guizhou UniversitySingapore National Research Foundation under its NRF Investigatorship(No.NRF-NRFI2016–06)Competitive Research Program(No.NRF-CRP22–2019–0002)Ministry of Education,Singapore,under its MOE Ac RF Tier 1 Award(Nos.RG7/20,RG70/21)MOE AcRF Tier 2(No.MOE2019-T2–2–117)MOE AcRF Tier 3 Award(No.MOE2018-T3–1–003)a Chair Professorship Grant,and Nanyang Technological University。
文摘Enones are widely explored in synthetic chemistry as fundamental building blocks for a wide range of reactions and exhibit intriguing biological activities that are pivotal for drug discovery.The development of synthetic strategies for highly efficient preparation of enones thereby receives intense attention,in particular through the transition metal-catalyzed coupling reactions.Here,we describe a carbene-catalyzed cross dehydrogenative coupling(CDC)reaction that enables effective assembly of simple aldehydes and alkenes to afford a diverse set of enone derivatives.Mechanistically,the in situ generated aryl radical is pivotal to“activate”the alkene by forming an allyl radical through intermolecular hydrogen atom transfer(HAT)pathway and thus forging the carbon-carbon bond formation with aldehyde as the acyl synthon.Notably,our method represents the first example on the enone synthesis through coupling of“non-functionalized”aldehydes and alkenes as coupling partners,and offers a distinct organocatalytic pathway to the transition metal-catalyzed coupling transformations.
基金supported by the National Natural Science Foundation of China (Nos. 21801067, U1804283, 21801066)the Central Plains Scholars and Scientists Studio Fund (No. 2018002)+2 种基金the Project funded by the Natural Science Foundation of Henan (Nos. 202300410225, 212300410181, 222102310562 and 201901023)China Postdoctoral Science Foundation (Nos. 2020T130176 and 2020M682306)financial support from Henan Key Laboratory of Organic Functional Molecules and Drug Innovation
文摘Ni(0)-catalyzed regio-and diastereodivergent[4+2]annulation of biphenylenes withα,βunsaturated ketones is described.This solvent-controlled diastereodivergent reaction integrates C-C bond cleavage of biphenylene and C=C double bond insertion selectivity,offering a mild approach to all possible diastereoisomers of 9,10-dihydrophenanthrene derivatives from the same starting materials.
基金the National Natural Science Foundation of China (Nos. 20773147, 21073211, and 21174155)
文摘A series of novel chiral diphosphite ligands have been synthesized from（1R,2R）-trans-1,2-cyclohexanediol,（1S,2S）-trans-1,2-cyclohexanediol, racemic trans-1,2-cyclohexanediol and chlorophosphoric acid diary ester, and were successfully employed in the Cu-catalyzed asymmetric 1,4-conjugate addition of diethylzinc to cyclohexenone with up to 99% ee. It was found that ligand 1,2-bis[（R）-1,10-binaphthyl-2,2＇-diyl]phosphitecyclohexanediol 6a derived from racemic diol skeleton can show similar catalytic performance compared with ligand（1R,2R）-bis[（R）-1,1＇-binaphthyl-2,2＇-diyl]phosphitecyclohexanediol 6a＇ derived from enantiopure starting material. A significant dependence of stereoselectivity on the type of enone and the ring size of the cyclic enone was observed. Moreover, the configuration of the products was mainly determined by the configuration of the binaphthyl moieties of diphosphite ligands in the 1,4-addition of cyclic enones.
基金the financial support from the Sichuan Science and Technology Program(No.2022NSFSC0619)。
文摘The asymmetric conjugate additions of aryl Grignard reagents to trisubstituted enones by chiral P,N ligand L6 with low catalyst loading(0.25–1.0 mol%)are disclosed.Chiral 2-ester chromanone and its analogs bearing a quaternary stereogenic centers at C2 position were produced in high to excellent yields,enantioselectivities and high turnover number.The notable features of this reaction include its broad substrate scope,complete 1,4-addition regioselectivities,applicability to both batch and flow for large scale synthesis.This report develops an efficient strategy to apply aryl Grignard reagents in asymmetric 1,4-conjugation reactions and provides a direct method to incorporate quaternary chiral centers toward the synthesis of biologically relevant chromanone derivatives.
基金the National Natural Science Foundation of China(Nos.21672176 and 21332007)the National Key R&D Program of China(grant No.2017YFA0207302)the Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT)of Ministry of Education.
文摘The efficient construction of functionalized polycyclic structures is an imports nt objective in organic synthesis.Herein,we disclose a three-step"[2+n]"annulation method for the transformation of cyclic ketones to fused enimines and enones.The method relies on the Suzuki coupling reaction and the amide reductive alkenylation reaction.A series of fused bicyclic(6/6,6/7,8/7)and tricyclic(6/6/6;6/6/7,6/5/7)ring systems bearing an α,β-enimine or an α,β-enone functionality have been synthetized in good overall yields.
基金supported in part by grants from the National Natural Science Foundation of China(NSFC,No.21971212)the Key Project of Innovation Research 2035 Pilot Plan of Southwest University,China(SWU-XDZD22007)+1 种基金the Research Fund for International Young Scientists from International(Regional)Cooperation and Exchange Program of NSFC(21850410447)the Research Funds for the Central Universities of China(XDJK2020C031).
文摘Alkaloids are one of the prominent members in the development of new antimicrobial agents.This work discovered a class of alkaloid quinazolone-derived imidazolenones as novel structural type of antibacterial agents with large potential to treat severe bacterial infections in the agricultural and food field.Preliminary bioactive assay displayed that some of the prepared compounds exhibited good inhibition against the tested strains,and cyclohexylimidazole-derived 7-fluoroquinazolone 22a(MIC=0.002 mmol/L)exhibited a 12.5-fold stronger inhibition than norfloxacin against Escherichia coli ATCC 25922.Further studies revealed that compound 22a not only possessed the ability of rapid bactericidal property and low propensity to develop resistance but also showed low cytotoxic effects toward red blood cells.The preliminary mechanism exploration indicated that compound 22a could cause membrane damage by disrupting bacterial membrane as well as depolarizing the cell membrane.Moreover,compound 22a could insert into DNA,which might hinder the replication of DNA.Molecular docking suggested that compound 22a could bind to gyrase and topoisomerase,which might be due to the suppressed expression of related genes.Meanwhile,compound 22a could disorder the metabolism and stimulate the production of reactive oxygen species to affect bacterial growth.The series of investigations suggested the promise of alkaloid quinazolone-derived imidazolenones as novel multitargeting antibacterial candidates for treatment of bacterial infections.
基金This project was financially supported by the Science,Technology and Innovation Commission of Shenzhen(Nos.KQTD20150717103157174,JCYJ20170817104350391)the National Natural Science Foundation of China(No.21801118)the Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002).
文摘Main observation and conclusion The enantioselective hydrogenation of endocyclic enones has been a historical problem for homogeneous catalysis.We herein report an efficient method to reduce endocyclic enones with molecular hydrogen.Catalyzed by a rhodium/Zhaophos complex,a variety of enones with five-,six-or seven-member ring were hydrogenated with high enantioselectivity(92%-99%ee).Excellent chemo-and enantioselectivity demonstrated this method was successfully applied in the enantioselective hydrogenation of citral to produce enantio-enriched citronellal.
基金the financial support from the National Natural Science Foundation of China(No.21921002)the NationalScience and Technology Major Project of the Ministry of Science and Technology of the People’s Republic of China(No.2018ZX09711001-005-004)the Fundamental Research Funds for the Central Universities(No.2012017yjsy210)。
文摘A convergent approach to 1,5-hydroxy ketones,the general precursors for constructing the C ring of bryostatins,has been developed via a Zn/Cu-promoted conjugate addition of a-hydroxy iodides with enones.The reaction leads to direct formation of the C21-C22 bond and tolerates diverse functionalities at the C17-,C18-and C24-positions.The approach also enables a more concise synthesis of the known C ring intermediate(10 longest linear steps and 14 total steps),in contrast to its previous synthesis(17 longest linear steps and 22 total steps) in our total synthesis of bryostatin 8.
文摘The nucleophilic addition of Ti(IV) enolate derived from methyl aryl ketones to α, β–unsaturated compounds was found to be highly selective to give 1, 2 addition products.
文摘A new enone (CH 3CO C( p NO 2C 6H 4COO)=CH S C 6H 4( p Br) 5, C 17 H 12 NBrO 5S, M r =422.25) was synthesized and its crystal structure was determined by X ray diffraction method. The crystal belongs to the monoclinic system, space group P2 1/c with a=6.4121(9), b=12.804(1), c=20.998(2) , β=94.884(9)°, V=1717.1(3) 3, Z=4, D c =1.633 g/cm 3, μ (Mo Kα )=2.542 mm -1 , F( 000)=848. Final R =0.0428 and wR =0.0916 for 3335 reflections with I>2σ(I) . The title compound exists as Z isomer with p bromothiophenolate and o nitrobenzoate groups cis arranged around asymmetrical centre. This observation suggests that the substitution of thiophenolate for bromine is a stereoselective step.
基金The National Natural Science Foundation of China(Nos.21901203,22171225,21925108)the Education Department of Shaanxi Province(No.20JK0934)are acknowledged for financial support.
文摘The first intermolecular electrophilic dearomatization of halonaphthols with benzyl/allyl bromides is described. Halonaphthols are used as carbon-nucleophiles in dearomatization to form three-dimensional cyclic enones with excellent chemoselectivity, in which etherification of phenolic hydroxyl group could be restrained well by using cesium carbonate as the base. A wide range of cyclic enones is directly prepared from various substituted benzyl/allyl bromides and halonaphthols. Mechanistic investigations suggest a direct S_(N)2 reaction pathway.
文摘Deconjugation of cyclopent-2-enone aldols were attempted under various conditions, and the desired deconjugated product was achieved via dianion approach. Various results obtained in this study are explained by structure and transition state analysis.
基金Supports from the National Natural Science Foundation of China (Nos. 21272257, 21274041 and 21474028)
文摘NTrifluoromethyl and cyclopropyl substituted 2-isoxazolines were synthesized via a DBU-promoted domino reaction of β-trifluoromethyl-/β-cyclopropyl-substituted enones with hydroxylamine. The domino reaction consists of a Michael addition and the followed cyclization. A wide range of 3-substituted 5-cyclopropyl-5-trifluoromethyl-2-isoxazolines were obtained in good to excellent yields under mild reaction conditions. The method could also apply to other trifluoromethyl-substituted enones.
基金the financial support from the National Natural Science Foundation of China(22001121)Nanjing Tech University。
文摘A catalyst-free and additive-free ring-opening reaction of polyfluoroalkyl peroxides,triethylenediamine(DABCO),and 1,2-dichloroethane(DCE)has been developed for the defluorinative synthesis of structurally diverse piperazines featuring a fluoroenone framework and a N-chloroethyl-substituent with high Z-stereoselectivity.The success of this three-component reaction is attributed to the in situ generation of an active 1-(2-chloroethyl)-1,4-diazabicyclo[2.2.2]octan-1-ium(DABCO·DCE)salt,which judiciously acts as a formal N-(2-chloroethyl)piperazine equivalent in the defluorinative coupling with less-studied aliphatic fluorinated substances.Impressively,this reaction accomplishes multi-activation of robust C(sp^(3))-F,C(sp^(3))-Cl,C(sp^(3))-O,and C(sp^(3))-N bonds in a one-pot process,offering a practical platform for the late-stage functionalization of complex molecules.Furthermore,the resulting products can not only serve as versatile building blocks for the synthesis of fluorinated heterocycles,but also undergo C—Cl bond displacement transformations with N-,O-,and S-nucleophiles.
基金supported by the National Natural Science Foundation of China(22002067,22202228)the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(20220052)+1 种基金the Science and Technology Project of Shanxi Province(202103021223457,202303021221256)Research Project Supported by Shanxi Scholarship Council of China.
文摘Catalytic dehydrogenation,with its exceptional atom economy and chemoselectivity,offers a highly desirable yet challenging approach for converting multiple environmentally friendly alcohols into crucial molecules.Furthermore,the utilization of catalysts based on abundant elements found on Earth for alcohol dehydrogenation to produce acryl ketone holds significant promise as a versatile strategy in synthesizing key building blocks for numerous pharmaceutical applications.The present study describes a practical Co-catalyzed cascade dehydrogenative Claisen condensation of secondary alcohols with esters,facilitating the synthesis of a wide range of 3-hydroxy-prop-2-en-1-ones.We introduce a catalytic system based on novel and scalable indazole NNP-ligands coordinated to cobalt for efficient dehydrogenations of secondary alcohols,and propose a plausible reaction mechanism supported by control experiments and labeling studies.Notably,it allows for the streamlined synthesis of multiple pharmaceuticals in one-pot.
基金theScienceCouncilandAcademiaSinicaofTaiwan China
文摘b Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529, China One pot hydroiodination and deconjugation of 5 aryloxy(or thiophenyl) 3 pentyn 2 one with a reagent system of sodium iodide/trimethylsilyl chloride/water in acetonitrile at 25 ℃ have been described. The plausible mechanism was discussed. The reaction provided a simple and useful method for the preparation of ( Z ) β substituted β,γ enones and ( Z ) β substituted α,β unsaturated ketones.
基金This work was supported by the National Natural Science Foundation of China(U19A2014,21890723).
文摘A highly enantioselective 1,3-dipolar cycloaddition ofα-substituted diazoesters with exocyclic enones was achieved with chiral scandium(III)/N,N’-dioxide complex as the catalyst.This protocol provided a facile and efficient route to optically active 1-pyrazoline-based spirochromanones and others with good outcomes(up to 97%yield,98%ee with>95:5 dr).Moreover,enantioenriched 2-pyrazoline-based spirochromanones were also accessible by switchingα-substituted diazoesters toα-diazoacetates.The further specific transformations of chiral pyrazoline-based spiro-compounds to spirocyclopropane derivatives were disclosed as well.
文摘The ethylene ketal of 2-cyelopentenone and 2-cyelohexenone in acetonitrile in the presence of a trace of an acid rapidly undergoes the Diels-Alder type dimerization,The products are regiospecific but not stereoselective and are hydrolysed sequentially to afford keto-ketals and diketones whose structures are determined by extensive applications of NMR spectroscopy.
