A NOVEL METHOD FOR SYNTHESIZING α,α-DISUBSTITUTED α-AMINO ACID——DIALKYLATION OF 2-OXAZOLIN-5-ONE

4,4-Dialkyl-2-oxazolin-5-ones are prepared by one step reaction of 2-oxazolin-5-one with the magnesium methyl carbonate(MMC)and alkyIhalides.It is a novel and convenient method for synthesis of α, Υ-disubstitutcd α-amino acid by hydrolysis of 4,4-dialkyl-2-oxazolin-5-ones.

Studies on steroidal plant growth regulator——27.Stereoselective construction of the side chain of brassinosteroid by employing a separated dialkylation and a tandem dialkylation of the pyranone moiety

A stereocontrolled construction of the side chain of brassinosteroid was developed via the separated dialkylation and the tandem dialkylation of the pyranone moiety as the key step.

葛根素-7-磷酰二烷基酯的电喷雾质谱研究

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.

Langmuir films stability phenomenon of glycerol dialkyl nonitol tetraether at the air-water interface for variations spreading time

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.

Synthesis, Spectral and Antimicrobial Studies of Bis (Cyclopentadienyl) Titanium (IV) Bis (O,O’-Dialkyl and Alkylenedithiophosphate) Complexes

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.

Synthesis and Spectroscopic Characterization of Eight Chloro Cyclopentadienyl Titanium Bis (O, O-Dialkyl and Alkylene Dithiophosphate) Compounds

A series of new complexes, CpTiCl[S2P(OR)2]2 (where R) Et, n-Pr, i-Pr, Bui, Ph) and CpTiCl [S2POGO]2 (where G) –CH2CMe2CH2-, -CMe2CMe2-) have been prepared by the drop wise addition of the appropriate O, O’-dialkyl or -alkylene dithiophosphoric acid to cyclopentadienyl titanium trichloride in 1:2 molar ratio and refluxed in benzene solution. The new compounds were characterized by molecular weight measurements elemental analyses and spectroscopic studies (1H, 13C, and 31P NMR, and in-frared). We suggest a distorted tetrahedron structure of these new complexes and the dithioligand behaves as bidentate ligand.

SYNTHESIS OF DIALKYL TETRABROMOPHTHALATES BY PTC AND THEIR FLAME RETARDANCY

Eight dialkyl tetrabromophthalates (DATBPs) were synthesized by reacting tetrabromophthalic anhydride with excess alcohols which were used not only as a reactant but also as a solvent and using a quaternary ammonium salt as a phase transfer catalyst (PTC). The yields were found to be between 85-93%. Their structures were characterized by IR, NMR and elementary analysis. The flame retardant properties of the compounds were also studied.

STUDIES ON ORGANOPHOSPHORUS COMPOUNDS 86 SOME NEW ASPECTS ON THE SYNTHESIS OF DIALKYL 1-ISOCYANO-BENZYL-AND/OR ALKYL-PHOSPHONATES

1-Isocyano substituted benzylphosphonates were prepared by dehydration of 1-N-formylamino substituted benzylphosphonates,which were obtained by a tricomponental condensation described by us.Mean- while addition of diethyl phosphite to N-trityl aldimine followed by deprotection,formylation and dehydration gave corresponding 1-isocyano alkylphosphonates in one-pot procedure.

Crystal Structure of Tris－（dimethoxyphosphato） Lanthanum（Ⅲ） Coordination Polymer｛La〔PO2（OCH3）2〕3｝n

ＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅｏｆＴｒｉｓ－（ｄｉｍｅｔｈｏｘｙｐｈｏｓｐｈａｔｏ）Ｌａｎｔｈａｎｕｍ（Ⅲ）ＣｏｏｒｄｉｎａｔｉｏｎＰｏｌｙｍｅｒ｛Ｌａ〔ＰＯ２（ＯＣＨ３）２〕３｝ｎ￥ＺｅｎｇＧｕａｎｇ－Ｆｕ；ＧｕｏＸｉｎ；ＷａｎｇＣｕｉ－Ｙ?..

Direct Synthesis of α-Aminophosphonates from Amines,Alcohols,and White Phosphorus

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.

Iridium-Catalyzed Asymmetric Hydrogenation of Dialkyl Imines

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.

青海湖地区全新世风尘堆积的GDGTs化合物及其环境指示意义

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。

A spirocyclic oxindole analogue:Synthesis and antitumor activities

A new synthesis of spirocyclic oxindole analogue spiro[piperidine-4,3＇-pyrrolol2,3-b]pyridin]-2＇（1＇H）-one 1 is described. The key steps involve dialkylation of arylacetonitrile and cyclization of the azaoxindole ring by an intramolecular Buchwald-Hartwig amidation of carboxylic amide and aryl chloride. A small library was obtained by reductive amination of 1 with various aldehydes and was screened against human lung cancer cell A549, human liver cancer cell BEL7402, and human colon cancer cell HCT-8. The results show that most of the library compounds 2 have some inhibitory activities. 2-（Trifluoromethoxy） benzylic substituted spirocyclic azaoxindole 2e was identified as a nanomolar inhibitor against human lung cancer cell A-549 （IC50 = 50 nmol/L）.

Paleoaltimetry proxies based on bacterial branched tetraether membrane lipids in soils

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.

Tandem synthesis of functionalized hexaalkyl benzoisoquinolinopyrrolonaphthyridine-hexacarboxylate, via isoquinoline based multi-component reaction

An expedient,synthetic method to fused polycyclic derivatives of isoquinoline is described via tandem reaction of isoquinoline,dialkyl acetylenedicarboxylates and dialkyl chloromalonate.

A facile one-pot synthesis of functionalized thiazines in water

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.

Three-component reaction of alkyl isocyanides with acetylenic esters and pyridine-2-carboxaldoxime or α-furildioxime:Synthesis and dynamic NMR study of ketenimines and bis(ketenimines)

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.

An effcient one-pot multi-component synthesis of 3,4,5-substituted furan-2(5H)-ones catalyzed by tetra-n-butylammonium bisulfate

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.

One-pot multicomponent synthesis of novel tricyclic pyrrolo[2,1-c][1,4]benzoxazines

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.

Effect of alkyl nitrite decomposition on catalytic performance of CO coupling reaction over supported palladium catalyst

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.