α-乙酰基二硫缩烯酮α碳原子的酰化反应

进行了α-乙酰基二硫缩烯酮与酰氯的酰化反应. 以干燥的二氯甲烷为溶剂, 在四氯化钛催化下, α-乙酰基环二硫缩烯酮(1)可与脂肪及芳酰氯(2)反应, 在化合物1的α-碳原子上发生酰化反应, 以较高的产率生成各种α-乙酰基-α-酰基二硫缩烯酮(3).     

5-核糖或木糖亚甲基-2,4-咪唑啉二酮衍生物的合成及其杀菌活性

以1,2:5,6-O-二异丙叉-α-D-呋喃葡萄糖为原料,经过吡啶重铬酸盐(PDC)氧化、NaBH4还原及选择性水解,实现α-D-木糖环向α-D-核糖环的C(3)位羟基构型的转化,然后分别在高碘酸钠氧化作用下得到糖环上C(5)位为醛基的α-D-木糖和α-D-核糖衍生物,它们分别与2,4-咪唑啉二酮-5-膦酸酯及2-硫代-2,4-咪唑啉二酮发生Wittig-Horner反应及Knoevenagel反应,分离得到3对5-核糖或木糖亚甲基-2,4-咪唑啉二酮衍生物顺反异构体,它们的化学结构经1H NMR,IR,MS和X射线单晶衍射确证.初步生物活性测定结果表明:在50μg/mL浓度下,部分目标化合物均对供试菌种显现出一定的抑制活性.     

无金属催化的吡啶C2位碳-氢键胺甲酰化反应合成吡啶甲酰胺

报道了一种无金属催化条件下合成吡啶-2-甲酰胺的方法.在质子酸的促进作用下，简单的吡啶和异氰通过2位碳-氢键的胺甲酰化反应生成吡啶-2-甲酰胺类化合物.产物的形成主要经历二水合草酸存在下异腈对吡啶环的亲电加成、水解和过氧化二叔丁酯氧化下的吡啶环芳构化转化.优化部分的对比实验证实质子酸和氧化剂的存在对于该反应都是必须条件.大体而言，所有反应都是将各反应物和试剂一次性加入，在空气氛围下100℃加热进行良好.环上不同位置含有甲基、叔丁基、环状二烷基、甲氧基、卤素等基团的吡啶底物均展示了良好兼容性.另一方面，烷基和芳基官能化的异腈也都能用于该反应，得到相应的N-烷基和N-芳基吡啶甲酰胺产物.初步结果显示异腈的稳定性对于反应结果有明显影响，相对稳定的2，6-二甲基苯基异腈参与反应生成的产物产率高于其它异腈参与的反应.和已知合成类似产物时采用银、钯盐等催化活化吡啶的2-位碳-氢键的方法相比，本文报道的合成方法优势在于完全无需金属催化剂、专一的碳-2位区域选择性反应、广泛的底物适用性以及高原子经济性.因此，这样的合成方法可望成为对已有合成方法的补充用于合成结构多样和有用的吡啶-2-甲酰胺化合物.     

钯促进的碳氢键活化在齐墩果酸D和E环脱氢烯化中的应用研究

齐墩果烷型的三萜及其糖苷化合物广泛分布于陆地植物和一些海洋生物中,是许多传统药物中的活性成分.这类五环三萜化合物的D和E环常发生羟基化的修饰,这些羟基及进一步的酰化或糖基化对这些化合物的活性非常重要.报道了利用最近发展的钯促进的碳氢键活化的方法,以齐墩果酸C28位羧基上缩合的8-胺基喹啉或2-氨甲基吡啶酰胺作为导向基团实现了对齐墩果酸D和E环的选择性脱氢烯化.这为进一步引入其他官能团奠定了基础.在此,N,N-双齿配体对于反应的顺利进行十分重要.     

富烯与2-吡啶甲基理及2-喹啉甲基锂的反应含氮杂环取代二茂铁的合成

在四氢呋喃 乙醚溶剂中,6-甲基-2-吡啶甲基锂与6,6-二烷基富烯或6,6-n亚甲基富烯(n=4,5,6)均发生环外双键加成反应.在类似反应条件下,2-喹啉甲基锂与6-甲基-6-乙基富烯或6,6-五亚甲基富烯皆发生加成反应和α-攫氢的竞争反应.用上述反应产生的取代环戊二烯基锂与二氯化铁配位,合成了一系列含氮杂环取代二茂铁衍生物.其结构经~1H NMR,元素分析和MS确证.在该类化合物的质谱裂解中,发现吡啶环对铁原子存在配位作用.     

不对称α-烃基-α-羟基丙二酰胺衍生物的合成新方法

N,N-二甲基氨甲酰基三甲基硅烷与一系列N-甲基-N-甲氧甲基α-羰基酰胺在无水无氧、105℃的条件下反应,合成了不对称α-烃基-α-羟基丙二酰胺类化合物或不对称α-烃基-α-三甲基硅氧基丙二酰胺衍生物,收率71%～86%,其结构用元素分析、1H NMR、13C NMR和IR等方法进行了表征.通过研究反应的影响因素发现,反应底物α-羰基酰胺中与α-羰基直接相连的烃基的空间位阻是该加成反应的重要影响因素,而α-羰基直接相连的芳环上取代基的电子效应则主要影响反应完成的时间.并提出了可能的反应机理.     

1,2,4-三苯基环戊二烯的合成及其烷基化反应

测定了颇哪醇在酸性条件下所得的脱水产物的分子结构.结果表明,在酸性条件下颇哪醇的脱水反应优于重排反应,由此合成了1,2,4-三苯基环戊二烯.该环戊二烯衍生物的烷基化反应,在通常条件下优先发生在碳环的第5位碳原子上,但在苛刻的剧烈反应条件下,进而发生在碳环的第3位碳原子上.讨论了脱水反应和烷基化反应的机理.     

氨甲酰基硅烷作氨酰基源与邻位二酮选择性氨酰化反应合成α-羟基-β-羰基仲(伯)酰胺衍生物

几种氨甲酰基硅烷与邻位二酮在无催化剂和氧化剂的温和条件下直接发生选择性氨酰化反应,制备了α-硅氧基-β-羰基仲(伯)酰胺衍生物,收率为62%～90%.氨甲酰基硅烷和邻位二酮的结构的空间位阻都影响在两个羰基上的反应选择性.氨基保护基甲氧甲基和苄基容易脱保护基转化成氢原子,得到α-羟基-β-羰基仲(伯)酰胺衍生物.通过选择不同氨甲酰基硅烷进行反应发现,此方法是选择性合成α-羟基-β-羰基叔酰胺、仲酰胺和伯酰胺衍生物的简易方法.该反应具有条件温和、副产物少、选择性強、产物得率高和后处理简单等优点,是有效合成α-羟基-β-羰基酰胺衍生物的新方法.     

6,6-二烷基富烯同α-吡啶甲基锂和α-吡啶基锂的反应——吡啶基取代环戊二烯及其铁衍生物的合成和结构

6,6-二烷基富烯和6,6-多亚甲基富烯同α-吡啶甲基锂发生环外双键的加成反应。形成的取代环戊二烯基锂经水解或与二氯化铁反应,分别制得α-吡啶烷基环戊二烯和α-吡啶烷基二茂铁。α-吡啶基锂与6,6-四亚甲基富烯进行α-摄氢反应,与6,6-五亚甲基富烯则发生环外双键的加成反应。 测定了双(η~5-1-(α-吡啶甲基)环戊基环戊二烯基)铁的分子结构。晶胞中含有三个分子,每个分子处在各自独立的位置。根据分子中两个环戊二烯基环上取代基的相对指向,分子Ⅰ与Ⅱ可以认为具有相同的构象,而分子Ⅲ则是它们的镜像。     

Phainanoids的4,5-螺环骨架的合成探索

本工作报道了用铑(I)催化芳基化环化反应和芳香亲核取代反应为关键步骤,合成天然产物Phainanoids的4,5-螺环骨架的探索.从已知化合物1出发,经过结构修饰得到炔酮5,在铑(I)催化条件下,与苯硼酸发生芳基化环化反应,构建了多取代环丁烯6.随后经过羟基保护和臭氧解反应得到α-烷氧基环丁酮8,其与格氏试剂9发生加成反应得到环丁醇10.最后在碱性条件下发生芳香亲核取代反应,在酸性条件下脱除乙氧基甲基(ethoxymethyl, EOM)和缩酮保护基,得到了4,5-螺环骨架结构18.格氏试剂9与邻烷氧基环丁酮8未能按照Cram’schelation模型进行与天然产物Phainanoids中螺环手性中心一致的立体选择性加成.综合文献报道和相关实验,可能的原因是:邻烷氧基环丁酮8的相对刚性结构,增加了镁离子与羰基氧原子和邻位烷氧基螯合过渡态的能垒;以及格氏试剂9中的氟原子与镁离子发生分子内螯合,抑制了镁离子与羰基邻位的烷氧基的螯合作用.     

Synthesis of 5-(5-amino-3,6-dichloro-1,4-benzoquinon-2-yl)-2-dimethylaminothiazoles and their properties

In the reaction of 2-dimethylamino-5-(3,5,6-trichloro-1,4-benzoquinon-2-yl)thiazole with primary and secondary amines, the chlorine atom at the 5-position of the benzoquinone ring is substituted, according to the ¹³C NMR spectroscopy data, by an amino group. The chemical, spectroscopic, and electrochemical properties of 5-(5-amino-3,6-dichloro-1,4-benzoquinon-2-yl)-2-dimethylaminothiazoles were revealed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 410–415, March, 1991.     

新型蓝光材料: 氟代三联(9,9-二苯基)芴的合成及其光电性能研究

使用HF/吡啶法在芴环的4位引入了氟原子, 使用五氟氯苯格氏试剂在芴环的9位引入了全氟苯, 合成了五个氟取代三联(9,9-二苯基)芴化合物. 测量了该系列化合物的电化学、光学和电致发光性能, 氟原子的引入提高了化合物的电子传输能力. 在溶液和薄膜状态下, 该类化合物都呈现出稳定的蓝光发射(色坐标x＝0.156, y＝0.078). 由化合物6f制备的简单器件的启亮电压为6 V, 最大亮度为452 cd/m2.     

Synthesis of N-acyl-4-methyl-7(8)nitro-2,3,4,5-tetrahydro-1H-1-5-benzodiazepin-2-ones and their spectral properties

The conditions were studied o f mono- and diacylation of 7(8)-nitro-2, 3, 4, 5-tetrahydro-1H-1, 5-benzodiazepin-2ones. It was found that under mild conditions (lower temperatures, weak acylating agents), the 7-nitro isomers are acylated only at the 5 -position; increase in the temperature or treatment with an active acylating agent gives the 1,5-diacyl derivatives. Under mild conditions the 8-nitro isomer is not acylated, while under more rigorous conditions a mixture of mono- and diacylated products is formed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 30, No. 1, pp. 99–105, January, 1994.     

Syntheses of 1,5,6-trimethyl-2-aminoimidazo[4,5-b]pyridine and 3,5,6-trimethyl-2-aminoimidazo[4,5-b]pyridine

Two potential mutagens found in food, 1,5,6-trimethyl-2-aminoimidazo[4,5-b]pyridine and 3,5,6-trimethyl-2-aminoimidazo[4,5-b]pyridine, are synthesized.     

Enhanced selectivities for the hydroxyl-directed methanolysis of esters using the 2-acyl-4-aminopyridine class of acyl transfer catalysts: ketones as binding sites

In this paper we describe the preparation of a series of 2-acyl-4-aminopyridines, and their use as catalysts for the hydroxyl-directed methanolysis of alpha-hydroxy esters in preference to alpha-methoxy esters. Hydroxyl-direction with these catalysts, which contain ketones at the 2-position of the pyridine, is achieved by reversible addition of the alcohol of the hydroxy ester to the ketone to provide the corresponding hemiketal. Their activity is compared to that of the previously described catalyst 2-formyl-4-pyrrolidinopyridine (FPP), which contains an aldehyde at the 2-position of the pyridine. The catalysts which contain ketones at the 2-position range in reactivity from 10 times slower to slightly faster than FPP, and certain of these are much more selective for the methanolysis of hydroxy esters than FPP. This increase in selectivity is ascribed to a decrease in the rate of the nondirected methanolysis reaction with the ketone-derived catalysts. The evidence suggests that the nondirected reaction does not proceed by an intermolecular general base mechanism, but rather via a nucleophilic catalysis mechanism in which the hydroxyl group of the hemiacetal formed upon addition of methanol to the aldehyde of FPP acts as the nucleophile. Since the hydroxyl group derived from a hemiketal is more hindered and less nucleophilic than that derived from a hemiacetal, the nondirected reaction is much slower for the catalysts containing ketones as binding sites.     

Regioselectivity of pyridine deprotonation in the gas phase

The regioselective deprotonation of pyridine in the gas phase has been investigated by using chemical reactivity studies. The mixture of regioisomers, trapped as carboxylates, formed in an equilibrium mixture is determined to result from 70-80% deprotonation in the 4-position, and 20-30% deprotonation at the 3-position. The ion formed by deprotonation in the 2-position is not measurably deprotonated at equilibrium because the ion is destabilized by lone-pair repulsion. From the composition of the mixture, the gas-phase acidities (DeltaH degrees acid) at the 4-, 3-, and 2-positions are determined to be 389.9 +/- 2.0, 391.2-391.5, and >391.5 kcal/mol, respectively. The relative acidities of the 4- and 3-positions are explained by using Hammett-Taft parameters, derived by using the measured gas-phase acidities of pyridine carboxylic acids. The values of sigmaF and sigmaR are -0.18 and 0.74, respectively, showing the infused nitrogen in pyridine to have a strong pi electron-withdrawing effect, but with little sigma-inductive effect.     

An infrared study of the tautomerism of chlorinated 2-pyridinols isolated in an argon matrix

The infrared spectra of 3-, 4-, 5- and 6-monochloro-, 3,5,6-trichloro-2-pyridinols (pyridones), and of the unsubstituted 2-pyridinol isolated in a low temperature (20°K) argon matrix were studied. The results indicate that the enol/keto ratio for the isolated pyridinols decreases according to the position of the chlorine atom(s) on the pyridine ring; i.e., 3,5,6-trichloro >-6 > 5 > 4 > 3 monochloro-2-pyridinols. 3,5,6-Trichloro-2-pyridinol exists predominantly in the enol form.     

Synthesis of 4-functionalized terdendate pyridine-based ligands

Four different 4-functionalised pyridine-based ligands were synthesized with aminomethyl, oxazolinyl, pyrazolyl and methylimidazolyl groups at the 2- and 6-position. The nitrogens of these groups together with the pyridine nitrogen can act as terdendate ligands for metal ions. Synthetic handles on the 4-position of the pyridine group were introduced via ether or ester bonds leading to monofunctional, bifunctional and amphiphilic ligands.     

Synthesis and Utility of Dihydropyridine Boronic Esters

When activated by an acylating agent, pyridine boronic esters react with organometallic reagents to form a dihydropyridine boronic ester. This intermediate allows access to a number of valuable substituted pyridine, dihydropyridine, and piperidine products.     

Saccharide recognition-induced transformation of pyridine-pyridone alternate oligomers from self-dimer to helical complex

Co-oligomers involving (1H)-4-pyridone and 4-alkoxypyridine rings were studied, and it was found that their supramolecular transformation was caused by saccharide recognition. In the co-oligomers, pyridone and pyridine rings are alternately linked at their 2,6-position with an acetylene bond. The pyridine rings behave as a hydrogen bonding acceptor, and the pyridone rings and tautomerized 4-pyridinol work as a donor. Pyridine-pyridone-pyridine 3-mer was found to self-dimerize on the basis of vapor pressure osmometry in CHCl(3), and the association constant was obtained as 2.3 x 10(3) M(-1) by (1)H NMR titration. Longer 5-, 7-, 9-, and 11-mer oligomers showed considerable broadening and anisotropy in the (1)H NMR spectra due to self-association. These longer oligomers recognized octyl beta-D-glucopyranoside and changed their form into a chiral helical complex, showing characteristic circular dichroism.