甲磺酸催化的选择性去甲基反应

选择性去甲基反应在天然产物的修饰、转化和合成中有重要的意义．首次报道甲磺酸可选择性脱除邻三甲氧基苯2位上的甲基以及3，4，5．三甲氧基苯甲酸甲酯和3，4，5-三甲氧基苯甲酸的4位上的甲基，为选择性脱除芳醚甲基提供了一个新的方法．     

一种新的5-甲氧基-1-（4-三氟甲基苯基）戊酮的合成方法

5-甲氧基-1-（4-三氟甲基苯基）戊酮是制备抗抑郁症药物马来酸氟伏沙明的关键中间体。本文介绍了一种由对三氟甲基幕甲酰氯与4-甲氧基丁基卤化镁在催化剂存在下合成5-甲氧基-1-（4-三氟甲基苯基）戊酮的方法。该方法包括三个主要步骤：步骤一为酰氯的制备。对三氟甲基苯甲酸和亚硫酰氯氯代得到对三氟甲基苯甲酰氯;步骤二为格氏试剂的制备,1-卤-4-甲氧基丁烷与金属镁反应得到格氏试剂;步骤三为酮的制备,对三氟甲基苯甲酰氯与上述格氏试剂在催化剂FeCl3存在下偶联得到5-甲氧基-1-（4-三氟甲基苯基）戊酮。该方法的特点是：原料易得,成本较低,反应周期短,效率较高;污染排放轻,对环境友好。     

两相体系中长链烯烃氢甲酰化反应研究--膦配体对活性和选择性的影响

在温和条件下合成了两种水溶性膦配体：三(4-甲氧基-3-磺酸钠苯基)膦(简称：4-MOTPPTS)和三(2-甲氧基-3-磺酸钠苯基)膦(简称：2-MOTPPTS)．在水／有机两相体系中，以RhCl(CO)(TPPTS)2为催化剂前体，考察了4-MOTPPTS和2-MOTPPTS作为配体时，膦／铑摩尔比、反应温度和压力变化对1-十二烯氢甲酰化反应催化性能的影响．结果表明，与三(3-磺酸钠苯基)膦(简称TPPTS)相比，在苯环上引入甲氧基后，其供电特性使催化剂对烯烃氢甲酰化反应的活性和生成醛的选择性不利，而邻位甲氧基的引入所造成的空间位阻，使2-MOTPPTS表现出较4-MOTPPTS更低的催化活性和选择性．但与相应的油溶性膦配体相比，对生成醛的选择性明显增加．     

半伏小薄孔菌Antrodiella Semisupina次级代谢产物研究

多孔菌半伏小薄孔经土豆液体发酵培养后,从乙酸乙酯提取物中分离得到5个次级代谢产物1-5,分别鉴定为erythro-1-(3′-氯-4′-甲氧基苯基)-1,2-丙二醇(1)、3-氯-4-甲氧基苯甲酸(2)、3,5-二氯-4-甲氧基苯甲酸(3)、3,4-二甲氧基苯甲酸(4)和对羟基苯甲酸(5).本文是首次报道半伏小薄孔菌次级代谢产物,其中化合物1-3为含氯代谢物,1,2和4为首次从陆生真菌中分离得到.     

α-溴-2，5-二甲氧基苯乙酮的合成

通过甲醇体系中利用溴化氢溴代仪α-氯2，5-二甲氧基苯乙酮的方法，获得了α-溴-2,5-二甲氧基苯乙酮，进一步和苯甲酸反应得到了苯甲酸-（2，5二甲氧基苯羰甲基）酯。研究表明该化合物在非极性溶剂苯中，没有光化学活性。在具有氢给体能力的甲醇溶剂中，也没有观察到任何光化学变化。     

2,3-二甲氧基-5-甲基-1,4-苯醌的合成

以对甲苯酚作原料,经过溴化,CuI催化合成2 ,6-二甲氧基-4甲基苯酚,再通过相转移反应合成 3,4 ,5-三甲氧基甲苯,最后用质量分数30%H₂O₂氧化得到较高收率的2 ,3-二甲氧基-5-甲基-1 ,4-苯醌醌     

取代基位置对含异噁唑二芳烯化合物性质的影响研究

本文合成了三种含异噁唑二芳基乙烯光致变色化合物{1-(3,5-二甲基异噁唑-4-基),2-[2-甲基-5-(2-甲氧基苯基)噻吩-3-基]}全氟环戊烯(1o),{1-(3,5-二甲基异噁唑-4-基),2-[2-甲基-5-(3-甲氧基苯基)噻吩-3-基]}全氟环戊烯(2o)和{1-(3,5-二甲基异噁唑-4-基),2-[2-甲基-5-(4-甲氧基苯基)噻吩-3-基]}全氟环戊烯(3o),研究了取代基位置对三种化合物的UV/Vis光谱和荧光性质的影响。实验结果表明,化合物1–3具有良好的光致变色性质和荧光性质;取代基的位置对化合物的性质有显著影响。     

2-对甲苯氧甲基-5-芳基-1,3,4-噁二唑化合物的合成与结构表征

对甲基苯氧乙酸乙酯与水合肼反应制得对甲基苯氧乙酰肼，该化合物在以碳酸钠作缚酸剂，分别与苯甲酰氯、4-氯苯甲酰氯、4-甲基苯甲酰氯、4-甲氧基苯甲酰氯、3，4，5-三甲氧基苯甲酰氯、3，5-二甲基苯甲酰氯和4-硝基苯甲酰氯反应得到相应的N，N’-二酰基肼3a一3g，然后在PC吗作用下，脱水环化成2-对甲苯氧甲基-5-芳基-1，3，4-噁二唑化合物4a-4g．通过元素分析，IR，’HNMS对其结构进行表征，并对其裂解途径进行了探讨。     

盐酸舒托必利的合成

以2-甲氧基-5-乙磺酰基苯甲酸为原料,合成了抗精神病药盐酸舒托必利。首先将2-甲氧基-5-乙磺酰基苯甲酸用甲醇酯化,制得2-甲氧基-5-乙磺酰基苯甲酸甲酯,产物与N-乙基-2-氨甲基四氢吡咯烷进行缩合反应得舒托必利,直接用浓盐酸成盐得盐酸舒托必利。合成路线工艺简便,条件温和,总收率57.5％。     

大野芋花香气成分分析及其综合开发应用前景

采用固相微萃取(SPME)-气相色谱/质谱(GC/MS)联用技术分析大野芋花的挥发性成分,共鉴定出12种挥发性化合物,其中含量较高的是2-异丙基-5-甲基茴香醚(46.88%),二氢-β-紫罗兰酮(39.80%),苯甲酸甲酯(6.61%),以上三种占鉴定总成分的93.29%.其中10种主要挥发性物质有香味,按花味分类,4-蒈烯、二氢-β-紫罗兰酮、4-(2,6,6-三甲基-环己烯-1-乙基)-2-丁醇、β-紫罗兰酮属紫罗兰花型;苯甲酸甲酯、1,2-二甲氧基苯、水杨酸甲酯、4-羟基-3-甲基苯乙酮(或称香草酮)、2-异丙基-5-甲基茴香醚、肉桂酸甲酯属芳香花型.可见,大野芋可作为良好的香料植物开发利用.     

Progress in the study of mercury methylation and demethylation in aquatic environments

Mercury(Hg) and its compounds are a class of highly toxic and pervasive pollutants.During the biogeochemical cycling of Hg,methylmercury(MeHg),a potent neurotoxin,can be produced and subsequently bioaccumulated along the food chain in aquatic ecosystems.MeHg is among the most widespread contaminants that pose severe health risks to humans and wildlife.Methylation of inorganic mercury to MeHg and demethylation of MeHg are the two most important processes in the cycling of MeHg,determining the levels of MeHg in aquatic ecosystems.This paper reviews recent progress on the study of Hg methylation and demethylation in aquatic environments,focusing on the following three areas:(1) sites and pathways of Hg methylation and demethylation,(2) bioavailability of Hg species for methylation and demethylation,and(3) application of isotope addition techniques in quantitatively estimating the net production of MeHg.     

Gadd45a promotes epigenetic gene activation by repair-mediated DNA demethylation

DNA methylation is an epigenetic modification that is essential for gene silencing and genome stability in many organisms. Although methyltransferases that promote DNA methylation are well characterized, the molecular mechanism underlying active DNA demethylation is poorly understood and controversial. Here we show that Gadd45a (growth arrest and DNA-damage-inducible protein 45 alpha), a nuclear protein involved in maintenance of genomic stability, DNA repair and suppression of cell growth, has a key role in active DNA demethylation. Gadd45a overexpression activates methylation-silenced reporter plasmids and promotes global DNA demethylation. Gadd45a knockdown silences gene expression and leads to DNA hypermethylation. During active demethylation of oct4 in Xenopus laevis oocytes, Gadd45a is specifically recruited to the site of demethylation. Active demethylation occurs by DNA repair and Gadd45a interacts with and requires the DNA repair endonuclease XPG. We conclude that Gadd45a relieves epigenetic gene silencing by promoting DNA repair, which erases methylation marks.     

低甲氧基果胶的研制

在酸法萃取、乙醇沉淀以制造高甲氧基果胶的工艺流程中,用盐酸进行部分脱酯,制得低甲氧基果胶.运用正交试验设计法,通过方差分析,检验脱酯温度、脱酯盐酸浓度以及脱酯时间对于产品酯化度、胶凝强度、纯度以及产率的影响的显著性.选择适宜的脱酯工艺条件.由干柚皮制得的低甲氧基果胶的酯化度为25.1%,胶凝强变为141.7°.正交设计法对于果胶系列产品的开发是行之有效的.     

IDH mutation impairs histone demethylation and results in a block to cell differentiation

Recurrent mutations in isocitrate dehydrogenase 1 (IDH1) and IDH2 have been identified in gliomas, acute myeloid leukaemias (AML) and chondrosarcomas, and share a novel enzymatic property of producing 2-hydroxyglutarate (2HG) from α-ketoglutarate. Here we report that 2HG-producing IDH mutants can prevent the histone demethylation that is required for lineage-specific progenitor cells to differentiate into terminally differentiated cells. In tumour samples from glioma patients, IDH mutations were associated with a distinct gene expression profile enriched for genes expressed in neural progenitor cells, and this was associated with increased histone methylation. To test whether the ability of IDH mutants to promote histone methylation contributes to a block in cell differentiation in non-transformed cells, we tested the effect of neomorphic IDH mutants on adipocyte differentiation in vitro. Introduction of either mutant IDH or cell-permeable 2HG was associated with repression of the inducible expression of lineage-specific differentiation genes and a block to differentiation. This correlated with a significant increase in repressive histone methylation marks without observable changes in promoter DNA methylation. Gliomas were found to have elevated levels of similar histone repressive marks. Stable transfection of a 2HG-producing mutant IDH into immortalized astrocytes resulted in progressive accumulation of histone methylation. Of the marks examined, increased H3K9 methylation reproducibly preceded a rise in DNA methylation as cells were passaged in culture. Furthermore, we found that the 2HG-inhibitable H3K9 demethylase KDM4C was induced during adipocyte differentiation, and that RNA-interference suppression of KDM4C was sufficient to block differentiation. Together these data demonstrate that 2HG can inhibit histone demethylation and that inhibition of histone demethylation can be sufficient to block the differentiation of non-transformed cells.     

A mammalian protein with specific demethylase activity for mCpG DNA

DNA-methylation patterns are important for regulating genome functions, and are determined by the enzymatic processes of methylation and demethylation. The demethylating enzyme has now been identified: a mammalian complementary DNA encodes a methyl-CpG-binding domain, bears a demethylase activity that transforms methylated cytosine bases to cytosine, and demethylates a plasmid when the cDNA is translated or transiently transfected into human embryonal kidney cells in vitro. The discovery of this DNA demethylase should provide a basis for the molecular and developmental analysis of the role of DNA methylation and demethylation.     

2-羟基咔唑的合成与表征

以邻溴硝基苯为起始原料,依次与双(频那醇合)二硼,对溴苯甲醚经Suzuki-Miyaura反应合成了2-硝基-4’-甲氧基联苯,然后经亚磷酸三乙酯还原反应,三溴化硼催化脱甲基化合成了目标产物2-羟基咔唑,总收率68.9%.通过1 HNMR、13 C NMR表征了合成化合物结构.