We have reported that phenyliodonium diacetate[PhI（OAc）2] can serve as an eco-friendly mild oxidant for the epoxidation of alkenes in the presence of Mn（III） complex of meso-tetrakis（4-methoxyphenylporphyrin） ac...We have reported that phenyliodonium diacetate[PhI（OAc）2] can serve as an eco-friendly mild oxidant for the epoxidation of alkenes in the presence of Mn（III） complex of meso-tetrakis（4-methoxyphenylporphyrin） acetate Mn[（T4-OCH3P）P]OAc and imidazole in CH2Cl2.The amounts of the products（%） and selectivities are very dependent upon the electronic and steric properties of the starting alkenes.To evaluate the validity of this catalytic system for C ＂H activation,cyclohexane and ethylbenzene were oxidized under the epoxidation conditions.展开更多
NaBH<sub>4</sub>, CH<sub>3</sub>CO<sub>2</sub>H, Pd/C has been described as an effective reagent system to hydrogenate alkenes. Here, we show that the hydrogenation occurs chemosele...NaBH<sub>4</sub>, CH<sub>3</sub>CO<sub>2</sub>H, Pd/C has been described as an effective reagent system to hydrogenate alkenes. Here, we show that the hydrogenation occurs chemoselectively, making it possible to hydrogenate alkenes under Pd/C catalysis with hydrogen created in situ without O- or N-debenzylation.展开更多
The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunction...The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunctional TiSn‐Beta zeolite was prepared by a simple and scalable post‐synthesis approach,and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2‐diols.The isolated Ti and Sn Lewis acid sites within the TiSn‐Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one‐step conversion of alkenes to 1,2‐diols with a high selectivity of>90%.Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product.Further,the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production.展开更多
A series of carboxylated long chain polyethylene glycols(abbreviated as PEGCOOH) has been synthesized and used to support chloroplatinic acid.These supported catalysts were then tested for their efficiency in the hydr...A series of carboxylated long chain polyethylene glycols(abbreviated as PEGCOOH) has been synthesized and used to support chloroplatinic acid.These supported catalysts were then tested for their efficiency in the hydrosilylation of alkenes.The factors affecting their catalytic properties,e.g.relative molecular mass of polyethylene glycol,reaction temperature,platinum content,and type of alkenes,have been studied.It was found that the activity of the platinum catalyst decreased with increasing length of the polyethylene glycol chain,and increased with reaction temperature.Moreover,these catalysts could be reused several times without a noticeable decrease in activity or selectivity.The reaction pathway leading to excellent selectivity for the β-adduct of hydrosilylation of alkenes with triethoxysilane catalyzed by this catalysis system was discussed.展开更多
The hydrothiolations of alkynes/alkenes with thiols is an atom-economic and thus attractive method for the constructions of C‒S bonds.Here Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposites with varied Ir_(2)S_(3)loadings were o...The hydrothiolations of alkynes/alkenes with thiols is an atom-economic and thus attractive method for the constructions of C‒S bonds.Here Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposites with varied Ir_(2)S_(3)loadings were obtained by one-pot solvothermal method from ZnCl_(2),InCl_(3)and thioacetamide with IrCl_(3).The loading of Ir_(2)S_(3)on the surface of ZnIn_(2)S_(4)promoted the hydrothiolations of alkenes and alkynes,with an optimum performance observed over 0.5 mol%Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposite.Based on the studies on the performance of several other cocatalysts(MoS2,NiS and Pd)loaded ZnIn_(2)S_(4)and the EIS analyses,it was proposed that the superior performance over Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposite can be ascribed to an improved efficiency on the photogeneration of the thiyl radicals by loading Ir_(2)S_(3)as well as its inactivity for photocatalytic hydrogen evolution,a side reaction in the light initiated hydrothiolation reaction over ZnIn_(2)S_(4).This study not only demonstrates an efficient and green strategy to synthesize thiolated products under visible light based on semiconductor photocatalysis,but also provides some guidances for the design and development of photocatalytic systems for light induced organic syntheses.展开更多
A Zn/NH4Cl system was exploited at room temperature to promote the Michael addition reaction of various primary and secondary amines with α,β-unsaturated esters,nitriles,amides,and ketones to give the corresponding ...A Zn/NH4Cl system was exploited at room temperature to promote the Michael addition reaction of various primary and secondary amines with α,β-unsaturated esters,nitriles,amides,and ketones to give the corresponding saturated amines under the mild condition in high yield.展开更多
Carbon-carbon double bond functional groups are often protected through a popular bromination/debromination method because of their reactivity. An ultrasonic-enhanced stereoselective debromination of vic-dibromides wi...Carbon-carbon double bond functional groups are often protected through a popular bromination/debromination method because of their reactivity. An ultrasonic-enhanced stereoselective debromination of vic-dibromides with metallic zinc powder in aqueous media has been developed, which generates E-alkenes with excellent yields. The reactivity of vic-dibromides decreases in the order of 1,2-dibromo-1,2-diphenylethane>1,2-dibromo-1-phenylethane>1,2-dibromo-1,2-dialkylethane.展开更多
The addition reactions of alkenes and alkynes to the H-terminated GaN （0001） surface with a Ga dangling-bond have been studied employing periodic density functional theory （PDFT） calculations. Detailed information...The addition reactions of alkenes and alkynes to the H-terminated GaN （0001） surface with a Ga dangling-bond have been studied employing periodic density functional theory （PDFT） calculations. Detailed information on the reaction pathways of these alkenes and alkynes with H-GaN （0001） surface is provided, which indicates that the reactions contain two steps separated by the metastable intermediates： elementary addition reaction and H-abstraction process. From the energy curves, the reactions are clearly viable in the cases of ethene, styrene and phenylacetylene; while for ethyne, the H-abstraction barrier is higher than the desorption barrier of the intermediate, so the adsorbed C2H2 in intermediate is more likely to be desorbed back into the gas phase than to form a stable adsorbed species. Furthermore, it is obvious that for either alkenes or alkynes, the systems substituted by phenyl have more stable intermediates because π conjugation could improve their stabilities.展开更多
Jacobsen's catalyst was immobilized onto SBA-15 by multi-step grafting, and this heterogenized catalyst exhibited comparable catalytic performance with the corresponding homogeneous counterpart for the epoxidation...Jacobsen's catalyst was immobilized onto SBA-15 by multi-step grafting, and this heterogenized catalyst exhibited comparable catalytic performance with the corresponding homogeneous counterpart for the epoxidation of alkenes, and the catalyst could be recycled effectively several times.展开更多
Z)-a-Selanyl alkenyl Grignard reagents 2 were prepared conveniently by treatment of a-bromovinylselenides 1 with magnesium filings in THF. Intermediates 2 were reacted with alkyl iodides in the presence of CuI or Pd(...Z)-a-Selanyl alkenyl Grignard reagents 2 were prepared conveniently by treatment of a-bromovinylselenides 1 with magnesium filings in THF. Intermediates 2 were reacted with alkyl iodides in the presence of CuI or Pd(PPh3)4 to afford (Z)-1,2-disubstituted vinylselenides 3, which were cross-coupled with Grignard reagents in the presence of (PPh3)2NiCl2 to give trisubstituted alkenes 4 stereoselectively in good yields.展开更多
Chiral activated alkene, L-menthyl acrylate and （＋）-N-α-phenylethyl acrylamide, induced asymmetric Baylis-HiUman reaction of aromatic aldehydes was realized at 25℃ for 7 days in Me3N/H2O/solvent homogeneous mediu...Chiral activated alkene, L-menthyl acrylate and （＋）-N-α-phenylethyl acrylamide, induced asymmetric Baylis-HiUman reaction of aromatic aldehydes was realized at 25℃ for 7 days in Me3N/H2O/solvent homogeneous medium. The corresponding Baylis-Hillman adducts were obtained in good chemical yield with moderate to excellent diastereoselectivity （up to 99% de）.展开更多
Despite hydroformylation being a very efficient method for the transformation of alkenes, it is not commonly employed in laboratories owing to the flammable/toxic nature of hydrogen and carbon monoxide gases and the n...Despite hydroformylation being a very efficient method for the transformation of alkenes, it is not commonly employed in laboratories owing to the flammable/toxic nature of hydrogen and carbon monoxide gases and the necessity of high-pressure equipment in a batch system. Flow chemistry often raises the safety profiles against high-pressure and toxic gases because the diameter of the flow reactor is small. Herein, we show that aliphatic alkenes can be safely hydroformylated in a flow reactor. In our flow method, although the target hydroformylated product was obtained in a low yield (19%), toxic gases were safely treated using a flow reactor. Better yields could possibly be achieved by recycling of the unreacted alkene.展开更多
A new synthetic method is described here to obtain α, β-unsaturated ketones through alkenes through a sequence involving f (1) cycloaddition of alkenes with dichloroketene, (2) dechlorination of adducts, (3)acidprom...A new synthetic method is described here to obtain α, β-unsaturated ketones through alkenes through a sequence involving f (1) cycloaddition of alkenes with dichloroketene, (2) dechlorination of adducts, (3)acidpromoted ring-opening isomerization ofcyclobutanones in CF3 CO2H.展开更多
By previously reported modified Masai-Rausch method of synthesizing titanocenocycles,followed by acid hydrolysis,trisubstituted al-kenes were synthesized,yields obtained are higher than that reported in literatures.St...By previously reported modified Masai-Rausch method of synthesizing titanocenocycles,followed by acid hydrolysis,trisubstituted al-kenes were synthesized,yields obtained are higher than that reported in literatures.Starting from unsymmetrical alkyne substrates,twelve different types of substituted alkenes were synthesized,among which only two were found single component,others were of mixed isomers.Beside conventional analytical methods,the NMR spectral analysis of titanocenoheterocycle intermediates and the products were used to identify the isomeric structures as well as their relative contents.展开更多
perfluoroalkyl iodides reacted with alkenes in acetonitrile solu- tion containing catalytic amount of organophosphine under mild condition to give the corresponding adducts in moderate to good yields.Reaction was show...perfluoroalkyl iodides reacted with alkenes in acetonitrile solu- tion containing catalytic amount of organophosphine under mild condition to give the corresponding adducts in moderate to good yields.Reaction was shown to involve a free radical mechanism.展开更多
Initiated by CP_2TiCl_2/Fe redox system,2-halotetrafluoroethyl iodides readily reacted with alkynes or alkenes to give 1:1 adducts in good to excellent yields.
The insertion of dichlorocarbene generated from chloroform by Phase Transfer Catalysis(PTC)into carbon-boron bond of dialkylborate anions 3,obtained by method A and B,resulted in the formation of the inter- mediates 5...The insertion of dichlorocarbene generated from chloroform by Phase Transfer Catalysis(PTC)into carbon-boron bond of dialkylborate anions 3,obtained by method A and B,resulted in the formation of the inter- mediates 5,which were oxidized with alkaline hydrogen peroxide to give the corresponding dialkylketones in 36-77.9% yields.展开更多
基金Supported by the Yasouj University Research Council and Department of Chemistry of Yasouj University,Iran
文摘We have reported that phenyliodonium diacetate[PhI（OAc）2] can serve as an eco-friendly mild oxidant for the epoxidation of alkenes in the presence of Mn（III） complex of meso-tetrakis（4-methoxyphenylporphyrin） acetate Mn[（T4-OCH3P）P]OAc and imidazole in CH2Cl2.The amounts of the products（%） and selectivities are very dependent upon the electronic and steric properties of the starting alkenes.To evaluate the validity of this catalytic system for C ＂H activation,cyclohexane and ethylbenzene were oxidized under the epoxidation conditions.
文摘NaBH<sub>4</sub>, CH<sub>3</sub>CO<sub>2</sub>H, Pd/C has been described as an effective reagent system to hydrogenate alkenes. Here, we show that the hydrogenation occurs chemoselectively, making it possible to hydrogenate alkenes under Pd/C catalysis with hydrogen created in situ without O- or N-debenzylation.
文摘The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunctional TiSn‐Beta zeolite was prepared by a simple and scalable post‐synthesis approach,and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2‐diols.The isolated Ti and Sn Lewis acid sites within the TiSn‐Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one‐step conversion of alkenes to 1,2‐diols with a high selectivity of>90%.Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product.Further,the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production.
基金Supported by the Educational Commission of Zhejiang Province of China (Y201017419)Zhejiang Province Program(2008C14041)
文摘A series of carboxylated long chain polyethylene glycols(abbreviated as PEGCOOH) has been synthesized and used to support chloroplatinic acid.These supported catalysts were then tested for their efficiency in the hydrosilylation of alkenes.The factors affecting their catalytic properties,e.g.relative molecular mass of polyethylene glycol,reaction temperature,platinum content,and type of alkenes,have been studied.It was found that the activity of the platinum catalyst decreased with increasing length of the polyethylene glycol chain,and increased with reaction temperature.Moreover,these catalysts could be reused several times without a noticeable decrease in activity or selectivity.The reaction pathway leading to excellent selectivity for the β-adduct of hydrosilylation of alkenes with triethoxysilane catalyzed by this catalysis system was discussed.
文摘The hydrothiolations of alkynes/alkenes with thiols is an atom-economic and thus attractive method for the constructions of C‒S bonds.Here Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposites with varied Ir_(2)S_(3)loadings were obtained by one-pot solvothermal method from ZnCl_(2),InCl_(3)and thioacetamide with IrCl_(3).The loading of Ir_(2)S_(3)on the surface of ZnIn_(2)S_(4)promoted the hydrothiolations of alkenes and alkynes,with an optimum performance observed over 0.5 mol%Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposite.Based on the studies on the performance of several other cocatalysts(MoS2,NiS and Pd)loaded ZnIn_(2)S_(4)and the EIS analyses,it was proposed that the superior performance over Ir_(2)S_(3)/ZnIn_(2)S_(4)nanocomposite can be ascribed to an improved efficiency on the photogeneration of the thiyl radicals by loading Ir_(2)S_(3)as well as its inactivity for photocatalytic hydrogen evolution,a side reaction in the light initiated hydrothiolation reaction over ZnIn_(2)S_(4).This study not only demonstrates an efficient and green strategy to synthesize thiolated products under visible light based on semiconductor photocatalysis,but also provides some guidances for the design and development of photocatalytic systems for light induced organic syntheses.
基金Supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education,China
文摘A Zn/NH4Cl system was exploited at room temperature to promote the Michael addition reaction of various primary and secondary amines with α,β-unsaturated esters,nitriles,amides,and ketones to give the corresponding saturated amines under the mild condition in high yield.
基金Supported by the National Natural Science Foundation of China(No.2 0 372 0 2 4 2 0 172 0 18) +2 种基金the Excellent ScientistFoundation of Anhui ProvinceChina(No.2 0 0 10 4 0 ) the Natural Science Foundation of the Educational Departm entof AnhuiProvince
文摘Carbon-carbon double bond functional groups are often protected through a popular bromination/debromination method because of their reactivity. An ultrasonic-enhanced stereoselective debromination of vic-dibromides with metallic zinc powder in aqueous media has been developed, which generates E-alkenes with excellent yields. The reactivity of vic-dibromides decreases in the order of 1,2-dibromo-1,2-diphenylethane>1,2-dibromo-1-phenylethane>1,2-dibromo-1,2-dialkylethane.
基金Supported by the National Natural Science Foundation of China (No 20673019)
文摘The addition reactions of alkenes and alkynes to the H-terminated GaN （0001） surface with a Ga dangling-bond have been studied employing periodic density functional theory （PDFT） calculations. Detailed information on the reaction pathways of these alkenes and alkynes with H-GaN （0001） surface is provided, which indicates that the reactions contain two steps separated by the metastable intermediates： elementary addition reaction and H-abstraction process. From the energy curves, the reactions are clearly viable in the cases of ethene, styrene and phenylacetylene; while for ethyne, the H-abstraction barrier is higher than the desorption barrier of the intermediate, so the adsorbed C2H2 in intermediate is more likely to be desorbed back into the gas phase than to form a stable adsorbed species. Furthermore, it is obvious that for either alkenes or alkynes, the systems substituted by phenyl have more stable intermediates because π conjugation could improve their stabilities.
文摘Jacobsen's catalyst was immobilized onto SBA-15 by multi-step grafting, and this heterogenized catalyst exhibited comparable catalytic performance with the corresponding homogeneous counterpart for the epoxidation of alkenes, and the catalyst could be recycled effectively several times.
文摘Z)-a-Selanyl alkenyl Grignard reagents 2 were prepared conveniently by treatment of a-bromovinylselenides 1 with magnesium filings in THF. Intermediates 2 were reacted with alkyl iodides in the presence of CuI or Pd(PPh3)4 to afford (Z)-1,2-disubstituted vinylselenides 3, which were cross-coupled with Grignard reagents in the presence of (PPh3)2NiCl2 to give trisubstituted alkenes 4 stereoselectively in good yields.
基金the National Natural Science Foundation of China(20472033)the Ph.D.Programs of Ministry of Education of China(No.20020055002)for generous financial support for our programs.
文摘Chiral activated alkene, L-menthyl acrylate and （＋）-N-α-phenylethyl acrylamide, induced asymmetric Baylis-HiUman reaction of aromatic aldehydes was realized at 25℃ for 7 days in Me3N/H2O/solvent homogeneous medium. The corresponding Baylis-Hillman adducts were obtained in good chemical yield with moderate to excellent diastereoselectivity （up to 99% de）.
文摘Despite hydroformylation being a very efficient method for the transformation of alkenes, it is not commonly employed in laboratories owing to the flammable/toxic nature of hydrogen and carbon monoxide gases and the necessity of high-pressure equipment in a batch system. Flow chemistry often raises the safety profiles against high-pressure and toxic gases because the diameter of the flow reactor is small. Herein, we show that aliphatic alkenes can be safely hydroformylated in a flow reactor. In our flow method, although the target hydroformylated product was obtained in a low yield (19%), toxic gases were safely treated using a flow reactor. Better yields could possibly be achieved by recycling of the unreacted alkene.
文摘A new synthetic method is described here to obtain α, β-unsaturated ketones through alkenes through a sequence involving f (1) cycloaddition of alkenes with dichloroketene, (2) dechlorination of adducts, (3)acidpromoted ring-opening isomerization ofcyclobutanones in CF3 CO2H.
文摘By previously reported modified Masai-Rausch method of synthesizing titanocenocycles,followed by acid hydrolysis,trisubstituted al-kenes were synthesized,yields obtained are higher than that reported in literatures.Starting from unsymmetrical alkyne substrates,twelve different types of substituted alkenes were synthesized,among which only two were found single component,others were of mixed isomers.Beside conventional analytical methods,the NMR spectral analysis of titanocenoheterocycle intermediates and the products were used to identify the isomeric structures as well as their relative contents.
文摘perfluoroalkyl iodides reacted with alkenes in acetonitrile solu- tion containing catalytic amount of organophosphine under mild condition to give the corresponding adducts in moderate to good yields.Reaction was shown to involve a free radical mechanism.
文摘Initiated by CP_2TiCl_2/Fe redox system,2-halotetrafluoroethyl iodides readily reacted with alkynes or alkenes to give 1:1 adducts in good to excellent yields.
文摘The insertion of dichlorocarbene generated from chloroform by Phase Transfer Catalysis(PTC)into carbon-boron bond of dialkylborate anions 3,obtained by method A and B,resulted in the formation of the inter- mediates 5,which were oxidized with alkaline hydrogen peroxide to give the corresponding dialkylketones in 36-77.9% yields.
