青海湖晚第四纪的古环境演化和湖面变化是学术界长期关注的热点问题，争议也较多。我们对青海湖地区种羊场（ZYC）剖面（120 cm厚）全新世风尘堆积的GDGTs （甘油二烷基甘油四醚）化合物相关指标的古环境意义进行了初步研究，以期从一...青海湖晚第四纪的古环境演化和湖面变化是学术界长期关注的热点问题，争议也较多。我们对青海湖地区种羊场（ZYC）剖面（120 cm厚）全新世风尘堆积的GDGTs （甘油二烷基甘油四醚）化合物相关指标的古环境意义进行了初步研究，以期从一个新的角度对上述问题进行探讨。研究结果表明：1） ZYC剖面的TEX86（由86个碳原子组成的四醚指标）与磁化率正相关，而Ri/b比值（类异戊二烯GDGTs与支链GDGTs丰度的比值）与磁化率负相关。2） ZYC剖面的TEX86指标与湖泊岩芯胖真星介（Eucypris inflata）壳体δ18O指示的7月古水温及长链烯酮（U37K）指示的夏季古水温变化具有相似的变化特征，显示TEX86指标较可靠地指示了青海湖地区的大气温度变化。然而，ZYC剖面的MBT （甲基化指数）和CBT （环化指数）指标在重建古气温方面具有一定的局限性，可能与青海湖地区全新世出现的干旱环境有关。3） ZYC剖面的Ri/b比值与湖泊岩芯E.inflata壳体Sr/Ca比值指示的青海湖湖水的古盐度具有较一致的变化特征，表明Ri/b比值较有效地指示了青海湖地区环境的干湿状况。4） TEX86和Ri/b指标揭示青海湖区在9.5~7.5 ka B.P.为冷干时期；7.5~5.5 ka B.P.为独特的温干阶段，温度在6.2 ka B.P.左右达到最高值；5.5~1.7 ka B.P.为温湿时期；1.7~0 ka B.P.为冷干时期。5）风尘堆积的GDGTs记录表明：7.5~5.5 ka B.P.由于环境干旱，青海湖不太可能出现高湖面；5.5~1.7 ka B.P.由于环境湿润，青海湖很可能出现全新世高湖面；1.7 ka B.P.以来，青海湖地区的气候快速变干。展开更多
A facile one-pot synthesis of 3,4,5-substituted furan-2（5H）-one derivatives from a three-component reaction of aniline derivatives, dialkylacetylenedicarboxylates and aromatic aldehydes under mild conditions using t...A facile one-pot synthesis of 3,4,5-substituted furan-2（5H）-one derivatives from a three-component reaction of aniline derivatives, dialkylacetylenedicarboxylates and aromatic aldehydes under mild conditions using tetra-n-butylammonium bisulfate as a catalyst has been developed.展开更多
The MBT/CBT （Methylation Index of Branched Tetraethers/Cyclisation ratio of Branched Tetraether） proxy, a terrestrial paleothermometer based on bacterial branched glycerol dialkyl glycerol tetraethers CoGDGTs）, was...The MBT/CBT （Methylation Index of Branched Tetraethers/Cyclisation ratio of Branched Tetraether） proxy, a terrestrial paleothermometer based on bacterial branched glycerol dialkyl glycerol tetraethers CoGDGTs）, was employed to indicate altimetry; however, the mechanistic control on this proxy is still ambiguous. Here, we investigated the bGDGTs＇ distribution and associated environmental factors along an altitude transect of Mt. Shennongjia in China in order to determine the applicability of bGDGT-based proxies to altimetry reconstruction. The MBT index exhibits only a weak correlation with estimated mean annual air temperature （MATe, estimated according to the meteorological record and lapse rate） or altitude. Likewise, MBT shows weak or no relationship with temperature or altitude at four other mountains （Mts. Meghalaya, Jianfengling, Gongga, and Rungwe）. It is notable that mean annual air temperature （MAT） or altitude estimated by the MBT/CBT proxy largely relies on CBT, rather than on MBT, which was generally acknowledged. The poor relationship between MBT and MATe for Mt. Shennongjia can be ascribed to the insensitive response of bGDGT-I to temperature. Our data fxom this mountain imply that care should be taken if the MBT/CBT proxy is employed as an indication of paleoaltimetry. We propose that the fractional abundance of bGDGTs may be a better paleoaltimeter than the MBT/ CBT proxy, because specific bGDGT subsets that might show the most sensitive response to temperature can be preferentially selected using a statistical method and used to establish local calibration. This local calibration was applied to Mt. Shennongjia and apparently improves the accuracy of temperature and altimetry reconstruction. The differential response of bGDGTs to temperature among mountains suggests that local calibrations are needed to better constrain the altimetry.展开更多
An expedient,synthetic method to fused polycyclic derivatives of isoquinoline is described via tandem reaction of isoquinoline,dialkyl acetylenedicarboxylates and dialkyl chloromalonate.
Developing practical strategies for the synthesis of organophosphorus compounds(OPCs)from white phosphorus(P_(4))without the use of Cl_(2) and PCl_(3) remains a significant challenge.The first multicomponent oxidative...Developing practical strategies for the synthesis of organophosphorus compounds(OPCs)from white phosphorus(P_(4))without the use of Cl_(2) and PCl_(3) remains a significant challenge.The first multicomponent oxidative α-phosphonylation of amines with P_(4) and alcohols has been developed.With the use of copper(Ⅱ)as the catalyst and air as the safe oxidant,structurally sophisticated α-aminophosphonates have been prepared in high yields.Furthermore,this method is also suitable for selective construction of P-O-P compounds.The reaction is characterized by a complete conversion of P_(4).The activation of P_(4) with transition metals often leads to formation of complexes[M_(x)P_(y)]_(n) associated with the deactivation of transition metals.This breakthrough showcases the potential of transition-metal-catalyzed reactions in elemental phosphorus chemistry.展开更多
Three-component reaction of arylsulfonamides,dialkyl acetylenedicarboxylates,and ethyl chlorooxoacetate promoted by triphenylphosphine and triethylamine provides a sufficient route for the synthesis of dialkyl N-（ary...Three-component reaction of arylsulfonamides,dialkyl acetylenedicarboxylates,and ethyl chlorooxoacetate promoted by triphenylphosphine and triethylamine provides a sufficient route for the synthesis of dialkyl N-（arylsulfonyl）-4-ethoxy-5-oxo-2,5-dihydro -1H-pyrolle-2,3-dicarboxylates in good yields.展开更多
Asymmetric hydrogenation of dialkyl imines to chiral amines is difficult because the two alkyls of imines are so similar in spatial and electronic structure that chiral catalysts are difficult to distinguish between t...Asymmetric hydrogenation of dialkyl imines to chiral amines is difficult because the two alkyls of imines are so similar in spatial and electronic structure that chiral catalysts are difficult to distinguish between them.In this study,we described an asymmetric hydrogenation of dialkyl imines by a chiral iridium catalyst containing spiro phosphine-amine-phosphine ligand.By precisely adjusting the chiral pocket of catalyst,a highly efficient catalyst was developed.Using this catalyst,a variety of dialkyl imines were hydrogenated to chiral amines with high yield and enantioselectivity.展开更多
Langmuir films behavior of asymmetric glycerol dialkyl nonitol tetraether (GDNT) lipids at the air-water interface (temperature 19℃ ± 1℃) investigated the stability of the mean ratio of Langmuir films for diffe...Langmuir films behavior of asymmetric glycerol dialkyl nonitol tetraether (GDNT) lipids at the air-water interface (temperature 19℃ ± 1℃) investigated the stability of the mean ratio of Langmuir films for different spreading time prior to the transfer film. Floating monolayer films stability is an important parameter to obtain high-quality Langmuir-Blodgett films for their aplications. Hysteresis loop of the compression-decompression (μ-A) isotherms of Langmuir film GDNT used to analyze the thermodynamic stability of the monolayer films and its features. Langmuir films stability of tetraether lipid GDNT shown more stable at the time of spreading longer than a short time.展开更多
Puerarin,an isoflavone compound,is the bioactive component of traditional Chinese medicine.A novel dialkyl puerarin-7-yl phosphate was synthesized and investigated by positive ion electrospray ionization ion trap mass...Puerarin,an isoflavone compound,is the bioactive component of traditional Chinese medicine.A novel dialkyl puerarin-7-yl phosphate was synthesized and investigated by positive ion electrospray ionization ion trap mass spectrometry (ESI MS)in conjunction with tandem mass spectrometry.The fragmentation pathways of dialkyl puerarin-7-yl phosphates were investigated.展开更多
Isoprenoidal glycerol dialkyl glycerol tetraethers （iGDGTs） from the Gulu hot springs （23--83.6 ℃, pH 〉 7） and Yangbajing hot springs （80-128 ℃, pH 〉 7） were analyzed in order to investigate the distribution...Isoprenoidal glycerol dialkyl glycerol tetraethers （iGDGTs） from the Gulu hot springs （23--83.6 ℃, pH 〉 7） and Yangbajing hot springs （80-128 ℃, pH 〉 7） were analyzed in order to investigate the distribution of archaeal lipids among different hot springs in Tibet. A soil sample from Gulu was incubated at different temperatures and analyzed for changes in iGDGTs to help evaluate whether surrounding soil may contribute to the iGDGTs in hot springs. The sources of bacterial GDGTs （bGDGTs） in these hot springs were also investigated. The results revealed different profiles ofiGDGTs between Gulu and Yangbajing hot springs. Core iGDGTs and polar iGDGTs also presented different patterns in each hot spring. The PCA analysis showed that the structure of polar iGDGTs can be explained by three factors and suggested multiple sources of these compounds. Bivariate correlation analysis showed significant positive correlations between polar and core bGDGTs, suggesting the in situ production of bGDGTs in the hot springs. Furthermore, in the soil incubation experiment, temperature had the most significant influence on concentration of bGDGTs rather than iGDGTs, and polar bGDGTs had greater variability than core bGDGTs with changing temperature. Our results indicated that soil input had little influence on the composition of GDGTs in Tibetan hot springs.展开更多
A simple synthesis of highly functionalized 2,5-diaminofurans based pyrimidine derivatives from 1-（carboxymethyl）uracil via a multi-component reaction is described. The reactive 1：1 intermediate produced from the r...A simple synthesis of highly functionalized 2,5-diaminofurans based pyrimidine derivatives from 1-（carboxymethyl）uracil via a multi-component reaction is described. The reactive 1：1 intermediate produced from the reaction of tert-butyl isocyanide and dialkyl acetylenedicarboxylates was trapped at room temperature by 1-（carboxymethyl）uracil derivatives to yield polyfunctio- nalized furan rings in fairly good yields.展开更多
A new complexes of Cp2Ti[S2P(OR)2]2 (where R = Et, Pr-n, Pr-i, Bu-i and Ph) and Cp2Ti[S2POGO]2 (where G = -CH2CMe2CH2-, -CH2CEt2CH2- and -CMe2CMe2-) were prepared by the dropwise addition of the appropriate O,O’-dial...A new complexes of Cp2Ti[S2P(OR)2]2 (where R = Et, Pr-n, Pr-i, Bu-i and Ph) and Cp2Ti[S2POGO]2 (where G = -CH2CMe2CH2-, -CH2CEt2CH2- and -CMe2CMe2-) were prepared by the dropwise addition of the appropriate O,O’-dialkyl or -alkylenedithiophosphoric acid to biscyclopentadienyl titanium dichloride in 1:2 molar ratio and refluxed in benzene solution. These novel deep red colored complexes were characterized by elemental analyses, molecular weight measurements and spectroscopic techniques (IR., NMR 1H, 13C and 31P NMR). These titanium (IV) dithio complexes have also been screened for their antibacterial activities.展开更多
A reaction between 1,3-dioxo-N-aryl-2,3-dihydro-lH-indene-2-carboxamides, dialkyl acetylenedicar- boxylates, and triphenylphosphine or trimethylphosphite is described as a simple and efficient method for the synthesis...A reaction between 1,3-dioxo-N-aryl-2,3-dihydro-lH-indene-2-carboxamides, dialkyl acetylenedicar- boxylates, and triphenylphosphine or trimethylphosphite is described as a simple and efficient method for the synthesis of 5-hydroxy-4-aryl-2,5-dihydrofuran-2,3-dicarboxylate derivatives.展开更多
An efficient synthesis of thiazines from the three component reactions between dialkyl acetylenedicarboxylates, arylisothio- cyanates and N-nucleophiles at room temperature in water as the solvent is described.
A mild and simple method for the synthesis of dialkyl chlorophosphates is described, bis（trichloromethyl） carbonate （BTC） is used as the effective reagent for the conversion of dialkyl phosphites to their correspo...A mild and simple method for the synthesis of dialkyl chlorophosphates is described, bis（trichloromethyl） carbonate （BTC） is used as the effective reagent for the conversion of dialkyl phosphites to their corresponding dialkyl chlorophosphates under mild conditions.展开更多
A simple and efficient synthetic protocol has been developed using a one-pot multicomponent reaction （MCR） involving 2-aminophenols, dialkyl acetylenedicarboxylates, and ethyl bromopyruvate in poly（ethyleneglycol）...A simple and efficient synthetic protocol has been developed using a one-pot multicomponent reaction （MCR） involving 2-aminophenols, dialkyl acetylenedicarboxylates, and ethyl bromopyruvate in poly（ethyleneglycol）. This protocol was utilized to prepare novel pyrrolo[2,1-c][1,4]benzoxazines in excellent yields.展开更多
The addition of pyridine-2-carboxaldoxime or α-furildioxime to dialkyl acety lenedicarboxy lates under neutral conditions in the presence of alkyl isocyanides leads to ketenimines and bis（ketenimines） in good yields.
Isoquinoline reacts with dialkyl acetylenedicarboxylates in the presence of kojic acid or8-hydroxyquinoline to generate 1,2-dihydroisoquinoline derivatives. The simplicity, mild reaction conditions and high yields of ...Isoquinoline reacts with dialkyl acetylenedicarboxylates in the presence of kojic acid or8-hydroxyquinoline to generate 1,2-dihydroisoquinoline derivatives. The simplicity, mild reaction conditions and high yields of products make it an interesting process compared to other approaches. The compounds have been analyzed for antibacterial activity against Gram negative and Gram positive bacteria. The results indicated that 1,2-dihydroisoquinolines derived from kojic acid are effective against all of the studied bacteria especially against Bacillus subtilis, while the products obtained from8-hydroxyquinoline are active only against Gram positive bacteria.展开更多
The syntheses of dimethyl oxalate （DMO） and diethyl oxalate （DEO） by CO coupling reaction in gaseous phase were investigated in a fixed bed reactor over Pd-Fe/ A1203 catalyst. The catalytic performance was charact...The syntheses of dimethyl oxalate （DMO） and diethyl oxalate （DEO） by CO coupling reaction in gaseous phase were investigated in a fixed bed reactor over Pd-Fe/ A1203 catalyst. The catalytic performance was characterized by CO conversion, space-time yield （STY） and selectivity of DMO （or DEO）. The results showed that over Pd-Fe/A1203 catalyst, the STY of DMO was higher than that of DEO under the same reaction conditions. The optimum reaction temperatures for synthesizing DMO and DEO were 403 K and 393 K, respectively, at the molar ratio 1：1 of alkyl nitrite to CO. The difference in synthesizing DMO and DEO on the same catalyst was attributed to the decomposition performances of methyl nitrite （MN） and ethyl nitrite （EN）, as density functional theory （DFT） calculation showed that EN decomposed more easily than MN.展开更多
A facile, one-pot synthesis of new phenanthridine derivatives by a three-component reaction between phenantridine, dialkyl acetylenedicarboxylates（DAADs）, and aromatic aldehydes is described. The reaction is charact...A facile, one-pot synthesis of new phenanthridine derivatives by a three-component reaction between phenantridine, dialkyl acetylenedicarboxylates（DAADs）, and aromatic aldehydes is described. The reaction is characterized by mild conditions, high selectivity, and tolerance to various functional groups.展开更多
文摘青海湖晚第四纪的古环境演化和湖面变化是学术界长期关注的热点问题，争议也较多。我们对青海湖地区种羊场（ZYC）剖面（120 cm厚）全新世风尘堆积的GDGTs （甘油二烷基甘油四醚）化合物相关指标的古环境意义进行了初步研究，以期从一个新的角度对上述问题进行探讨。研究结果表明：1） ZYC剖面的TEX86（由86个碳原子组成的四醚指标）与磁化率正相关，而Ri/b比值（类异戊二烯GDGTs与支链GDGTs丰度的比值）与磁化率负相关。2） ZYC剖面的TEX86指标与湖泊岩芯胖真星介（Eucypris inflata）壳体δ18O指示的7月古水温及长链烯酮（U37K）指示的夏季古水温变化具有相似的变化特征，显示TEX86指标较可靠地指示了青海湖地区的大气温度变化。然而，ZYC剖面的MBT （甲基化指数）和CBT （环化指数）指标在重建古气温方面具有一定的局限性，可能与青海湖地区全新世出现的干旱环境有关。3） ZYC剖面的Ri/b比值与湖泊岩芯E.inflata壳体Sr/Ca比值指示的青海湖湖水的古盐度具有较一致的变化特征，表明Ri/b比值较有效地指示了青海湖地区环境的干湿状况。4） TEX86和Ri/b指标揭示青海湖区在9.5~7.5 ka B.P.为冷干时期；7.5~5.5 ka B.P.为独特的温干阶段，温度在6.2 ka B.P.左右达到最高值；5.5~1.7 ka B.P.为温湿时期；1.7~0 ka B.P.为冷干时期。5）风尘堆积的GDGTs记录表明：7.5~5.5 ka B.P.由于环境干旱，青海湖不太可能出现高湖面；5.5~1.7 ka B.P.由于环境湿润，青海湖很可能出现全新世高湖面；1.7 ka B.P.以来，青海湖地区的气候快速变干。
基金fnancial support from the Research Council of the University of Sistan and Baluchestan
文摘A facile one-pot synthesis of 3,4,5-substituted furan-2（5H）-one derivatives from a three-component reaction of aniline derivatives, dialkylacetylenedicarboxylates and aromatic aldehydes under mild conditions using tetra-n-butylammonium bisulfate as a catalyst has been developed.
文摘The MBT/CBT （Methylation Index of Branched Tetraethers/Cyclisation ratio of Branched Tetraether） proxy, a terrestrial paleothermometer based on bacterial branched glycerol dialkyl glycerol tetraethers CoGDGTs）, was employed to indicate altimetry; however, the mechanistic control on this proxy is still ambiguous. Here, we investigated the bGDGTs＇ distribution and associated environmental factors along an altitude transect of Mt. Shennongjia in China in order to determine the applicability of bGDGT-based proxies to altimetry reconstruction. The MBT index exhibits only a weak correlation with estimated mean annual air temperature （MATe, estimated according to the meteorological record and lapse rate） or altitude. Likewise, MBT shows weak or no relationship with temperature or altitude at four other mountains （Mts. Meghalaya, Jianfengling, Gongga, and Rungwe）. It is notable that mean annual air temperature （MAT） or altitude estimated by the MBT/CBT proxy largely relies on CBT, rather than on MBT, which was generally acknowledged. The poor relationship between MBT and MATe for Mt. Shennongjia can be ascribed to the insensitive response of bGDGT-I to temperature. Our data fxom this mountain imply that care should be taken if the MBT/CBT proxy is employed as an indication of paleoaltimetry. We propose that the fractional abundance of bGDGTs may be a better paleoaltimeter than the MBT/ CBT proxy, because specific bGDGT subsets that might show the most sensitive response to temperature can be preferentially selected using a statistical method and used to establish local calibration. This local calibration was applied to Mt. Shennongjia and apparently improves the accuracy of temperature and altimetry reconstruction. The differential response of bGDGTs to temperature among mountains suggests that local calibrations are needed to better constrain the altimetry.
基金Sanandaj Branch, Islamic Azad University Research Council for the fnancial support of this research
文摘An expedient,synthetic method to fused polycyclic derivatives of isoquinoline is described via tandem reaction of isoquinoline,dialkyl acetylenedicarboxylates and dialkyl chloromalonate.
基金the National Key Research and Development Program of China(grant no.2020YFA0608300)the Space Application System of China Manned Space Program(grant no.KJZ-YY-WSM01)National Natural Science Foundation of China(grant nos.21772163,21778042,and 41876072).
文摘Developing practical strategies for the synthesis of organophosphorus compounds(OPCs)from white phosphorus(P_(4))without the use of Cl_(2) and PCl_(3) remains a significant challenge.The first multicomponent oxidative α-phosphonylation of amines with P_(4) and alcohols has been developed.With the use of copper(Ⅱ)as the catalyst and air as the safe oxidant,structurally sophisticated α-aminophosphonates have been prepared in high yields.Furthermore,this method is also suitable for selective construction of P-O-P compounds.The reaction is characterized by a complete conversion of P_(4).The activation of P_(4) with transition metals often leads to formation of complexes[M_(x)P_(y)]_(n) associated with the deactivation of transition metals.This breakthrough showcases the potential of transition-metal-catalyzed reactions in elemental phosphorus chemistry.
基金the financial support from the Research Council of Islamic Azad University,Mahshahr Branch
文摘Three-component reaction of arylsulfonamides,dialkyl acetylenedicarboxylates,and ethyl chlorooxoacetate promoted by triphenylphosphine and triethylamine provides a sufficient route for the synthesis of dialkyl N-（arylsulfonyl）-4-ethoxy-5-oxo-2,5-dihydro -1H-pyrolle-2,3-dicarboxylates in good yields.
基金supported by the National Key R&D Program of China(grant no.2022YFA1504302)the National Natural Science Foundation of China(grant nos.22188101,91956000,and 92256301)the Fundamental Research Funds for the Central Universities,and the Haihe Laboratory of Sustainable Chemical Transformations.
文摘Asymmetric hydrogenation of dialkyl imines to chiral amines is difficult because the two alkyls of imines are so similar in spatial and electronic structure that chiral catalysts are difficult to distinguish between them.In this study,we described an asymmetric hydrogenation of dialkyl imines by a chiral iridium catalyst containing spiro phosphine-amine-phosphine ligand.By precisely adjusting the chiral pocket of catalyst,a highly efficient catalyst was developed.Using this catalyst,a variety of dialkyl imines were hydrogenated to chiral amines with high yield and enantioselectivity.
文摘Langmuir films behavior of asymmetric glycerol dialkyl nonitol tetraether (GDNT) lipids at the air-water interface (temperature 19℃ ± 1℃) investigated the stability of the mean ratio of Langmuir films for different spreading time prior to the transfer film. Floating monolayer films stability is an important parameter to obtain high-quality Langmuir-Blodgett films for their aplications. Hysteresis loop of the compression-decompression (μ-A) isotherms of Langmuir film GDNT used to analyze the thermodynamic stability of the monolayer films and its features. Langmuir films stability of tetraether lipid GDNT shown more stable at the time of spreading longer than a short time.
文摘Puerarin,an isoflavone compound,is the bioactive component of traditional Chinese medicine.A novel dialkyl puerarin-7-yl phosphate was synthesized and investigated by positive ion electrospray ionization ion trap mass spectrometry (ESI MS)in conjunction with tandem mass spectrometry.The fragmentation pathways of dialkyl puerarin-7-yl phosphates were investigated.
基金supported by the National Natural Science Foundation of China(Grant No.40972211)the US National Science Foundation(Grant Nos.ETBC-1024614 and OISE- 0968421 )
文摘Isoprenoidal glycerol dialkyl glycerol tetraethers （iGDGTs） from the Gulu hot springs （23--83.6 ℃, pH 〉 7） and Yangbajing hot springs （80-128 ℃, pH 〉 7） were analyzed in order to investigate the distribution of archaeal lipids among different hot springs in Tibet. A soil sample from Gulu was incubated at different temperatures and analyzed for changes in iGDGTs to help evaluate whether surrounding soil may contribute to the iGDGTs in hot springs. The sources of bacterial GDGTs （bGDGTs） in these hot springs were also investigated. The results revealed different profiles ofiGDGTs between Gulu and Yangbajing hot springs. Core iGDGTs and polar iGDGTs also presented different patterns in each hot spring. The PCA analysis showed that the structure of polar iGDGTs can be explained by three factors and suggested multiple sources of these compounds. Bivariate correlation analysis showed significant positive correlations between polar and core bGDGTs, suggesting the in situ production of bGDGTs in the hot springs. Furthermore, in the soil incubation experiment, temperature had the most significant influence on concentration of bGDGTs rather than iGDGTs, and polar bGDGTs had greater variability than core bGDGTs with changing temperature. Our results indicated that soil input had little influence on the composition of GDGTs in Tibetan hot springs.
基金supported by the Research Council of the University of Mazandaran,Iran
文摘A simple synthesis of highly functionalized 2,5-diaminofurans based pyrimidine derivatives from 1-（carboxymethyl）uracil via a multi-component reaction is described. The reactive 1：1 intermediate produced from the reaction of tert-butyl isocyanide and dialkyl acetylenedicarboxylates was trapped at room temperature by 1-（carboxymethyl）uracil derivatives to yield polyfunctio- nalized furan rings in fairly good yields.
文摘A new complexes of Cp2Ti[S2P(OR)2]2 (where R = Et, Pr-n, Pr-i, Bu-i and Ph) and Cp2Ti[S2POGO]2 (where G = -CH2CMe2CH2-, -CH2CEt2CH2- and -CMe2CMe2-) were prepared by the dropwise addition of the appropriate O,O’-dialkyl or -alkylenedithiophosphoric acid to biscyclopentadienyl titanium dichloride in 1:2 molar ratio and refluxed in benzene solution. These novel deep red colored complexes were characterized by elemental analyses, molecular weight measurements and spectroscopic techniques (IR., NMR 1H, 13C and 31P NMR). These titanium (IV) dithio complexes have also been screened for their antibacterial activities.
文摘A reaction between 1,3-dioxo-N-aryl-2,3-dihydro-lH-indene-2-carboxamides, dialkyl acetylenedicar- boxylates, and triphenylphosphine or trimethylphosphite is described as a simple and efficient method for the synthesis of 5-hydroxy-4-aryl-2,5-dihydrofuran-2,3-dicarboxylate derivatives.
文摘An efficient synthesis of thiazines from the three component reactions between dialkyl acetylenedicarboxylates, arylisothio- cyanates and N-nucleophiles at room temperature in water as the solvent is described.
基金the National Basic Research Program of China 973 Program(No.2003CB114400)the National Natural Science Foundation of China(No.20476098)for financial support.(No.20676123)
文摘A mild and simple method for the synthesis of dialkyl chlorophosphates is described, bis（trichloromethyl） carbonate （BTC） is used as the effective reagent for the conversion of dialkyl phosphites to their corresponding dialkyl chlorophosphates under mild conditions.
基金Sanandaj Branch,Islamic Azad University Research Council for the financial support
文摘A simple and efficient synthetic protocol has been developed using a one-pot multicomponent reaction （MCR） involving 2-aminophenols, dialkyl acetylenedicarboxylates, and ethyl bromopyruvate in poly（ethyleneglycol）. This protocol was utilized to prepare novel pyrrolo[2,1-c][1,4]benzoxazines in excellent yields.
文摘The addition of pyridine-2-carboxaldoxime or α-furildioxime to dialkyl acety lenedicarboxy lates under neutral conditions in the presence of alkyl isocyanides leads to ketenimines and bis（ketenimines） in good yields.
文摘Isoquinoline reacts with dialkyl acetylenedicarboxylates in the presence of kojic acid or8-hydroxyquinoline to generate 1,2-dihydroisoquinoline derivatives. The simplicity, mild reaction conditions and high yields of products make it an interesting process compared to other approaches. The compounds have been analyzed for antibacterial activity against Gram negative and Gram positive bacteria. The results indicated that 1,2-dihydroisoquinolines derived from kojic acid are effective against all of the studied bacteria especially against Bacillus subtilis, while the products obtained from8-hydroxyquinoline are active only against Gram positive bacteria.
文摘The syntheses of dimethyl oxalate （DMO） and diethyl oxalate （DEO） by CO coupling reaction in gaseous phase were investigated in a fixed bed reactor over Pd-Fe/ A1203 catalyst. The catalytic performance was characterized by CO conversion, space-time yield （STY） and selectivity of DMO （or DEO）. The results showed that over Pd-Fe/A1203 catalyst, the STY of DMO was higher than that of DEO under the same reaction conditions. The optimum reaction temperatures for synthesizing DMO and DEO were 403 K and 393 K, respectively, at the molar ratio 1：1 of alkyl nitrite to CO. The difference in synthesizing DMO and DEO on the same catalyst was attributed to the decomposition performances of methyl nitrite （MN） and ethyl nitrite （EN）, as density functional theory （DFT） calculation showed that EN decomposed more easily than MN.
文摘A facile, one-pot synthesis of new phenanthridine derivatives by a three-component reaction between phenantridine, dialkyl acetylenedicarboxylates（DAADs）, and aromatic aldehydes is described. The reaction is characterized by mild conditions, high selectivity, and tolerance to various functional groups.
