An efficient green MCR protocol for the stereoselective synthesis of β-acetamido ketones catalyzed by Selectfluor™

An efficient, green, room temperature process for the stereoselective synthesis of β-amido ketones employing a one-pot multi-component reaction of aromatic aldehydes, α-substituted or α-unsubstituted ketones, an acid chloride, and a nitrile in presence of catalytic amount of Selectfluor^™ is described. The process offers advantages such as high anti-selectivity, shorter reaction time, energy efficiency, and simple work-up.     

基金“拥挤交易”对A股股价泡沫的影响研究

随着基金数量的不断增加,多家基金重仓一只股票所呈现的“拥挤交易”现象日渐明显。本文运用面板数据模型,对基金“拥挤交易”与A股股价泡沫之间的关系进行考察。结果表明,当公司超过6只基金重仓持股时,基金拥挤交易会对股价泡沫形成促进作用;当小于6只基金重仓持股时,这一关系则不显著。即:基金拥挤交易需要在“拥挤”到一定程度后才会促进股价泡沫膨胀。因此,管理层应高度重视6家以上基金重仓持股的股票,这类股票往往会形成较大的泡沫,同时也存在较大的崩溃风险。另外,管理层还应审慎研究政策出台时可能带来的预期,最大限度的避免基金经理产生一致的信念和一致行动,降低基金拥挤交易现象的发生。     

包含双边投资规范的自由贸易协定网络

当今国际经济趋势表明,包含投资规范的双边自由贸易协定(bilateral FTAs)受到了越来越多国家的欢迎。通过假定双边自由贸易协定包含着无限制对外直接投资规范,基于Goyal和Joshi(2006)^[1],本文构建了相应FTA网络形成博弈模型。本文发现:(1)星状FTA网络是两两稳定的;(2)从空FTA网络到星状FTA网络存在一条个体国家福利和世界福利都严格改善的路径。     

随机需求下基于商业信用的回购与收入共享联合契约协调研究

在由单个供应商和单个零售商组成的供应链中,零售商由于资金短缺或风险规避不能达到系统的最优订货量,因此需要采取一些措施使得供应链节点企业间相互合作来实现供应链的协调。本文针对需求随机且供应链节点企业存在缺货惩罚的情况,通过设计基于商业信用(即供应商允许零售商延期支付货款)的完全回购契约来促进零售商提高订购量,以实现供应链系统达到最优利润,分析给出了该契约下的最优订货量和批发价格;在此基础上,为了合理分配供应链系统的总利润,建立了回购与收入共享联合契约模型,发现通过共享系数的变动能够实现供应链系统协调和渠道成员双赢。     

Analysis on International Competitiveness of Service Trade in the Guangdong–Hong Kong–Macao Greater Bay Area Based on Using the Entropy and Gray Correlation Methods

Based on the analysis and measurement of the overall situation, import and export structure and international competitiveness of the various sectors of service trade in the Guangdong–Hong Kong–Macao Greater Bay Area, with the help of MATLAB and Gray System Modeling software, the synergy degree model was established to quantitatively analyze the synergy level of service trade in the Greater Bay Area with the help of grey correlation analysis method and entropy weight method. The results show that the overall development trend of service trade in the Guangdong–Hong Kong–Macao Greater Bay Area is good. The service trade industries in different regions are highly complementary and have a high degree of correlation. The potential for the coordinated development of internal service trade is excellent, and the overall situation of service trade in the Greater Bay Area is in a stage of transition from a moderate level of synergy to a high level of synergy. The Greater Bay Area can achieve industrial synergy by accelerating industrial integration and green transformation, establishing a coordinated development mechanism, sharing market platform, strengthening personnel security, and further enhancing the international competitiveness of service trade. The established model better reflects the current coordination of service trade in the Guangdong–Hong Kong–Macao Greater Bay Area and has good applicability. In the future, more economic, technological, geographic, and policy data and information can be comprehensively used to study the spatial pattern, evolution rules, and mechanisms of coordinated development in the broader area.     

世界水产品贸易竞争力与产业内贸易分析

对世界水产品贸易及中国在世界水产品贸易中的地位进行了分析,并运用比较优势系数和产业内贸易指标,对世界主要水产品出口国的水产品竞争力和产业内贸易分别进行了测算和分析.结果表明,世界和中国的水产品出口贸易规模均在不断扩大,中国各类水产品及水产品加工的国际比较优势也在不断提升,欧关主要发达国家普遍存在水产品的产业内贸易为中国水产品出口提供了机遇.     

Synthesis of TRITON™ X-based phosphate ester surfactants and their self-charring behavior

This paper describes the synthesis and characterization of a series of TRITON™ X-based surfactants with a predominantly alkyl phenol ethoxylate (APE) backbone and a phosphate ester chain end. Four phosphate-terminated TRITON™ X (or APE) derivatives (OPE2-OPO(OH)₂, OPE5-OPO(OH)₂, OPE10-OPO(OH)₂, and NPE10-OPO(OH)₂) were prepared from commercially available octyl phenol ethoxylate (OPE) of different oxyethylene units (n = 2, 5 and 10), nonyl phenol ethoxylate (NPE) of 10 oxyethylene units and phosphorous pentoxide via a simple condensation reaction. Depending on their composition and chain length of oxyethylene units used in the reaction, the surfactants show different self-charring behaviors. The phosphate-terminated TRITON™ X of the lowest number of oxyethylene units (i.e. OPE2-OPO(OH)₂) gives the largest amount of char (up to 23 wt%) at 600 °C under air condition. The carboxylic acid-terminated TRITON™ X derivatives (i.e. OPE-COOH) were also tested for comparison.     

Rearrangements accompanying fluorination of 2-amino alcohols and 1,2-diols with Deoxo-Fluor™

2-Amino alcohols and 1,2-diols treated with Deoxo-Fluor™ in methylene chloride resulted in the formation of rearranged major products concomitantly with minor amounts of the straightforward fluorinated replacement products in good yields.     

Polymer-supported thioanisole: a versatile platform for organic synthesis reagents

A new cross-linked polystyrene-supported thioanisole reagent is reported. This reagent incorporates the flexible JandaJel™ cross-linker and can be treated with methyl trifluoromethanesulfonate to form the corresponding sulfonium salt. This salt can in turn be deprotonated to form a polymer-supported sulfur ylide that is able to react with aldehydes and ketones to form epoxides. The thioanisole reagent can also be oxidized to form an insoluble sulfoxide reagent that is useful in Swern oxidation reactions. In these reactions, the polymer-supported thioanisole-based reagents can be recovered, regenerated and reused.     

Room temperature preparation of α-chloro-β,β-difluoroethenylzinc reagent (CF2CClZnCl) by the metallation of HCFC-133a (CF3CH2Cl) and a high yield one-pot synthesis of α-chloro-β,β-difluorostyrenes

α-Chloro-β,β-difluorovinylzinc reagent [CF₂CClZnCl] was generated in 91% yield by the metallation of a THF solution of commercially available HCFC-133a (CF₃CH₂Cl) and zinc chloride at 15-20 °C using LDA as base. The corresponding reaction with Halothane™ (CF₃CHClBr) produced a poor yield of CF₂CClZnCl. The palladium catalyzed coupling reaction of the CF₂CClZnCl with aryl iodides under mild reaction conditions produced α-chloro-β,β-difluorostyrenes in 64-90% isolated yields. The stability of the intermediate CF₂CClLi and the nature of the zinc reagents are discussed.