甲基取代的甲酸态的四氢叶酸辅酶模型的合成及其取代碳 …

以乙二胺和乙酰胺为原料，经４步反应合成了碘化１，２－二甲基－３－间（或对）－硝基苯磺酰基咪唑啉（２ａ，２ｂ）以２ａ和２ｂ作为甲基取代的甲酸态四氢叶酸辅酶模型，同单亲核中心的氮亲核体（对甲苯胺，对甲氧基苯胺等）和碳亲核体（丙二腈）反应得到次惭基单元（ＣＨ３－Ｃ≤）转移的中间体产物，与双亲核中心的亲核体（邻苯二胺，邻氨基酚）反应得到次乙基单元完全转移的产物。     

四氢叶酸辅酶模型的合成及甲基取代的一碳单元转移反应

本文报道了甲基取代的甲酸态的四氢叶酸辅酶模型--碘化1, 2-二甲基-3-对氯苯磺酰基咪唑啉的合成。研究了模型与单官能团亲核体(苯胺、对氯苯胺、对硝基苯胺)和双官能团亲核体(邻苯二胺、邻氨基酚、乙二胺)作用, 转移甲基取代的一碳单元的反应。     

碘化1-甲基-2-异丙基(或丙基)-3-苯磺酰基咪唑啉的合成及基团转移反应

合成了新的四氢叶酸辅酶(THF)模型化合物碘化1-甲基-2-异丙基-3-苯磺酰基咪唑啉(5a)和碘化1-甲基-2-丙基-3-苯磺酰基咪唑啉(5b),研究了其反应性能.结果表明,化合物5与双官能团亲核体邻苯二胺或邻氨基苯酚反应,完全转移了4个碳的异丁基和正丁基单元,基于此探索了合成2-取代苯并咪唑及2-取代苯并唑的新方法;化合物5a与单官能团亲核体胺类反应部分转移了4个碳的异丁基单元,生成不同基团取代的N,N,N'-三取代乙二胺盐;化合物5a在Na BH4作用下可发生还原反应,在Na OH水溶液中可发生水解反应,也可与碳负离子基团(硝基甲基负离子或二腈基甲基负离子)发生亲核加成反应,生成了3类不同基团取代的N,N,N'-三取代乙二胺衍生物,探索了此类化合物的简易合成方法.这些反应模拟了四氢叶酸辅酶在生物体内转移一碳单元的功能,并将其扩展到4个碳原子单元,获得了可应用于有机合成的新方法和新试剂.     

四氢叶酸辅酶结构和性能的模拟及取代一碳单元转移反应的研究

本工作模拟了四氢叶酸辅酶的结构和反应性能, 合成了模型化合物碘化1, 2-二甲基-3-对甲氧苯磺酰基咪唑啉, 研究了模型化合物与单官能团亲核体、双官能团亲核体相作用, 以甲酸、甲醛氧化态转移取代一碳单元[≡C-CH~3, =C(CH~3)CH~2NO~2]的反应, 部分反应生成了咔啉类生物碱衍生物和其它杂环类化合物。     

四氰乙烯齐聚体的反应;V.全氟3,4-二甲基-4-乙基-2-己烯和含硫亲核试剂的反应及其衍生物的转化

全氟3,4-二甲基-4-乙基-2-己烯(1)和含硫亲核试剂如苄硫酚、烯丙硫酚及苯硫酚等的反应及反应产物的转化可得四类异构体2,3,4,5;在-30～-60℃于乙醚中反应,得到动力学控制的产物2a～c.2a,2b与KF在DMF中,室温反应可转化为热力学稳定的产物3a,3b,在100～120℃,2a～c异构化为4a～c.后者在DMF-KF中室温反应,重排成5a～c.在DMF-NEt3中2a再和苄硫粉反应得到连二苄硫醚(6)和含氢的端基烯7a及二取代产物8a,在乙醚-三乙胺中反应得到3a和9a,2a和甲醇反应,可得少量3a和10a,2b和二乙胺反应复杂,仅得少量3b和不饱和酰胺11。     

四氟乙烯齐聚体的反应——Ⅴ.全氟3,4-二甲基-4-乙基-2-己烯和含硫亲核试剂的反应及其衍生物的转化

全氟3,4-二甲基-4-乙基-2-己烯(1)和含硫亲核试剂如苄硫酚、烯丙硫酚及苯硫酚等的反应及反应产物的转化可得四类异构体2,3,4,5;在-30～-60℃于乙醚中反应,得到动力学控制的产物2a～c。2a,2b与KF在DMF中,室温反应可转化为热力学稳定的产物3a,3b。在100～120℃,2a～c异构化为4a～c。后者在DMF-KF中室温反应,重排成5a～c。在DMF-NEt_3中2a再和苄硫酚反应得到连二苄硫醚(6)和含氢的端基烯7a及二取代产物8a,在乙醚-三乙胺中反应得到3a和9a。2a和甲醇反应,可得少量3a和10a。2b和二乙胺反应复杂,仅得少量3b和不饱和酰胺11。     

α-氧代烯酮环二硫代缩酮化学(ⅩⅫ) ——硫醇(酚)为亲核体的α-氧代烯酮环二硫代缩酮与2-甲基烯丙基氯化镁加成物的取代-环合芳构化反应

缩酮基为五元和六元环的α-氧代烯酮环二硫代缩酮与2-甲基烯丙基氯化镁反应得1,2-加成产物。所得加成产物在酸催化条件下以乙硫醇为亲核体时生成芳基乙基硫醚;苯硫酚为亲核体时,产物为芳基苯基硫醚。同样实验条件下,缩酮基为甲硫基的α-氧代烯酮二硫代缩酮与2-甲基烯丙基氯化镁的1,2-加成则生成芳构化产物芳基甲基硫醚。本实验从亲核体的选用上进一步拓展了所述取代-环合芳构化反应,并进一步验证了缩酮基结构对反应活性的影响。     

2-甲基-3-双取代基-4,5-二氢异噁唑衍生物的合成及其拆分

3-(1′,2′-二-O-环己叉二氧乙基)异噁唑啉盐(2)与MeMgBr(或在二异丙基胺和正丁基锂存在下与乙酸乙酯)进行亲核加成反应合成了2,3-二甲基-3-(1′,2′-二-O-环己叉二氧乙基)-4,5-二氢异噁唑(3)[或2-甲基-3-(乙氧羰甲基)-3-(1′,2′-二-O-环己叉二氧乙基)-4,5-二氢异噁唑(4)]。3和4经MPLC拆分得到了非对映体3a,3b,4a和4b,其结构经1HNMR,13C-NMR,IR和元素分析表征。     

二苯并卤五环盐与多种碳亲核试剂的反应

我们前曾报道过3,7-二硝基二苯并碘五环盐1及3,7-二硝基二苯并溴五环盐2与一些非碳亲核试剂的反应[1,2].最近我们研究了1和2与多种碳亲核试剂(丙二酸二乙酯单钠盐a、氰乙酸乙酯单钠盐b、硝基甲烷单钠盐c、丙二腈单钠盐d)的反应,其中1与a,b的反应及2与a的反应得到了比较满意的结果,主产物分别为相应的亲核取代产物3a,3b及5a.1与c,d的反应亦得到预期的产物3c及3d,但产率较低.2与b,c的反应则未能得到预期的碳亲核取代产物.对上述实验结果进行了讨论.     

氧桥联双核钛、镍配合物的合成及催化制备双峰聚乙烯

从2种氧原子桥联双膦化合物双(2-二苯基膦苯基)醚(1a)和4,5-双(二苯基膦)-9,9-二甲基氧杂蒽(1b)出发,合成氧原子桥联双膦亚胺钛、镍配合物.在甲苯中回流条件下首先将化合物1a和1b与叠氮三甲基硅烷发生Staudinger反应,分别生成单和双膦亚胺前驱体2a和2b.然后再与环戊二烯基三氯化钛反应,脱去三甲基氯硅烷后得到相应膦亚胺过渡金属钛配合物3a和3b.单钛中心配合物3b进一步与乙二醇二甲醚溴化镍反应生成钛-镍异核双中心配合物4b.通过1H NMR,13C NMR,31P NMR,FTIR及元素分析对产物进行了表征,并利用X射线单晶衍射分析确定了配合物3a和3b的分子结构.在助催化剂甲基铝氧烷(MAO)作用下,配合物3a和4b对乙烯聚合均表现出较高的催化活性,其中双钛中心配合物3a催化得到较宽分子量的聚乙烯产物,而异核双中心配合物4b催化得到呈双峰分布的聚乙烯产物.     

十六烷基三甲基溴化铵相转移催化合成N,N—二乙基苯胺的研究

十六烷基三甲基溴化铵相转移催化合成Ｎ，Ｎ－二乙基苯胺的研究田庆伟（大连铁道学院应用化学系大连１１６０２８）关键词十六烷基三甲基溴化铵相转移催化Ｎ，Ｎ－二乙基苯胺中图分类号０６２５．６３１Ｎ，Ｎ－二乙基苯胺是制备染料、药物和彩色显影剂的重要中间体，用途...     

Improved asymmetric S(N)Ar reaction of beta-dicarbonyl compounds catalyzed by quaternary ammonium salts derived from cinchona alkaloids

The scope and limitation of the asymmetric nucleophilic aromatic substitution reaction of alpha-substituted 1,3-dicarbonyl compounds and activated aromatic systems catalyzed by N-benzyl-O-benzoylcinchoninium or cinchonidinium salts are presented. Several novel O-benzoylcinchona alkaloid derived salts have been prepared and evaluated as catalysts in this reaction, which can proceed with enantioselectivites up to 96% ee. Various 1,3-dicarbonyl compounds and activated aromatic systems are evaluated for the aromatic nucleophilic substitution reaction, and it has been found that the yield and enantioselectivity are very dependent on the substrate and reagent. The scope of the functionalization of the products to, e.g., spiro-oxoindole, a ring-opening reaction of 1,3 alpha,alpha-disubstituted dicarbonyl compounds with several nucleophiles, and the diastereoselective reduction of the keto functionality in the optically active S(N)Ar product are reported.     

Diazotization of Methyl 3-Amino-7-Isopropyl-2-Methoxyazulene-1-Carboxylate and its 5-Isopropyl Isomer- a Convenient Synthesis of 1,2-Azulenequinone Derivatives

Methyl 3-amino-2-methoxy-7-isopropylazulene-l-carboxylate( 8a ) and its 5-isopropyl isomer ( 8b ) were synthesized by reduction of the 3-nitro derivatives ( 7a,b ) with zinc/acetic acid in excellent yields. 7a and 7b were prepared by nitration and methylation of methyl 7-isopropyl-2-hydroxyazulene-l-carboxylate ( 5a ) and methyl 5-isopropyl-2-hydroxyazulene-l-carboxylate ( 5b ), respectively. Diazotization of 8a with sodium nitrite in trifluoroacetic acid at 0 °C gave methyl 5-isopropyl-1,2-azulenequinone-3-carboxylate ( 9a ) in 91% yield. Similar reaction of 8b gave the corresponding methyl 7-isopropyl-1,2-azulenequinone-3-carboxylate ( 9b ) in 93% yield. No evidence for the formation of l-diazo-1,2-azulenequinones was obtained.     

烯基取代的甲酸态四氢叶酸辅酶模型的合成及其碳单元转移反应

以邻苯二胺和乙酸为原料,经3步反应合成了8种烃基乙烯基取代的苯并咪唑盐,其结构用元素分析,¹HNMR,IR,MS和UV-Vis进行了表征,并以其作为取代的甲酸态四氢叶酸辅酶模型,同亲核试剂(格氏试剂)反应得到烃基乙烯基取代的一碳单元完全转移的产物α,β-不饱和酮,为α,β-不饱和酮的合成提供了一种简便的仿生合成新方法.     

The rates of S(N)2 reactions and their relation to molecular and solvent properties

The energy barriers of symmetrical methyl exchanges in the gas phase have been calculated with the reaction path of the intersecting/interacting-state model (ISM). Reactive bond lengths increase down a column of the Periodic Table and compensate for the decrease in the force constants, which explains the near constancy of the intrinsic barriers in the following series of nucleophiles: F(-) approximately Cl(-) approximately Br(-) approximately I(-). This compensation is absent along the rows of the Periodic Table and the trend in the reactivity is dominated by the increase in the electrophilicity index of the nucleophile in the series C相似文献   

2,3—二甲基吡嗪合成工艺的改进

报道了以丁二酮和乙二胺为原料，对液相合成２，３－二甲基吡嗪的方法进行了改进，考察了反应温度，溶剂用量和脱氢剂等对反应影响，确定了合成２，３－二甲基吡嗪的优化条件为，丁二酮：乙二胺（摩尔比）＝１：１．０５；丁二酮：溶剂无水乙醇（体积比）＝１：１０，缩合反应温度：－５℃，时间：１ｈ，脱氢剂：ＤＨＫＭ－１２，脱氢温度：８０～８５℃，时间：１ｈ２，３－二甲基吡嗪的产率按投料丁二酮设计达６５％。     

A theoretical investigation of alpha-carbon kinetic isotope effects and their relationship to the transition-state structure of S(N)2 reactions

[reaction: see text] The transition structures and alpha-carbon 12C/13C kinetic isotope effects for 22 S(N)2 reactions between methyl chloride and a wide variety of nucleophiles have been calculated using the B1LYP/aug-cc-pVDZ level of theory. Anionic, neutral, and radical anion nucleophiles were used to give a wide range of S(N)2 transition states so the relationship between the magnitude of the alpha-carbon kinetic isotope effect and transition-state structure could be determined. The results suggest that the alpha-carbon 12C/13C kinetic isotope effects for S(N)2 reactions will be large (near the experimental maximum) and that the curve relating the magnitude of the KIE to the percent transfer of the alpha-carbon from the nucleophile to the leaving group in the transition state has a broad maximum. This means very similar KIEs will be found for early, symmetric, and late transition states and that one cannot use the magnitude of these KIEs to estimate transition-state structure.     

Reactivity of a sterically hindered Fe(II) thiolate dimer with amines and hydrazines

The sterically hindered Fe(II) thiolate dimer Fe(2)(mu-STriph)(2)(STriph)(2) (1; [STriph](-) = 2,4,6-triphenylbenzenethiolate) reacts with primary amines ((t)BuNH(2), aniline) and N(2)H(4) to form the structurally characterized addition complexes Fe(STriph)(2)(NH(2)(t)Bu)(2), Fe(2)(mu-STriph)(2)(STriph)(2)(NH(2)Ph)(2), and Fe(2)(mu-eta(1):eta(1)-N(2)H(4))(2)(N(2)H(4))(4)(STriph)(4) in high yield. Chemical and NMR spectroscopic evidence indicate that the binding of these nitrogen donors is labile in solution and multispecies equilibria are likely. With arylhydrazines, 1 catalytically disproportionates 1,2-diphenylhydrazine to aniline and azobenzene, and it rearranges 1-methyl-1,2-diarylhydrazines to give, after treatment with alumina, mononuclear, trigonal bipyramidal Fe(III) complexes of composition Fe(ISQ)(2)(STriph), where [ISQ](-) denotes an appropriately substituted bidentate o-diiminobenzosemiquinonate ligand. Complex 1 shows no reaction with hindered 1,2-dialkylhydrazines (isopropyl or tert-butyl) or tetrasubstituted 1,2-dimethyl-1,2-diphenylhydrazine.     

Determination of regioselectivity in ring opening of tert-butylaziridinones by a combination of (15)N labeling and electrospray ionization-ion trap mass spectrometry

The ring opening of 1,3-di-tert-butylaziridinone by tert-butylamine and aniline was investigated by using electrospray ionization and collision-induced dissociation in an ion trap mass spectrometer in conjunction with (15)N labeling of the two amine nucleophiles. Using the MS(n) capabilities of the ion trap instrument, we were able to monitor the retention of the (15)N label through successive fragmentation steps. Both amines exhibited a remarkable degree of selectivity in that they both cleaved exclusively the 1,3-bond (the alkyl-nitrogen bond). This result is in contrast to that obtained previously with methylamine, which cleaved just the opposite bond, namely, the 1,2-bond (the acyl-nitrogen bond). These contrasting results could not have been predicted by previously published guidelines.