八乙基卟啉及其锌配合物的分子和晶体结构

测定了中位(meso)取代八乙基卟啉和无轴向配位卟啉锌(II)配合物的结构, 讨论了锌离子配位前后卟啉环的平面性, 并比较了有锌和无锌配位卟啉阴离子的几何构型。研究结果表明卟啉骨架的构型不仅决定于卟啉骨架中央孔穴的大小, 配位离子的尺寸和电子结构, 而且还决定于骨架上的取代基团。本文还分析了在卟啉骨架上取代硝基的几何构型以及它们在卟啉共轭效应中的作用。     

八乙墓卟啉和四苯基卟啉合钌(Ⅱ)及锇(Ⅱ)的二氧加合物的红外光谱

ＯＥＰ（八乙基卟啉阴离子）和ＴＰＰ（四苯基卟啉阴离子）合钌（Ⅱ）和锇（Ⅱ）的二氧加合物由ｍａｔｒｉｘ分离技术得到（Ｔ＝２０－４３Ｋ，Ｐ＝１０＾－５－１０＾－６ｔｏｒｒ）。为了确定ν（Ｏ２）带的归属应用于同位素取代法＾１６Ｏ２／＾１８Ｏ２。ＩＲ谱说明对于钌的两种加合物（指ＯＥＰ和ＴＰＰ）都有两种异构体，其ν（＾１６Ｏ２）频率为：Ｒｕ（ＯＥＰ）Ｏ２，１１４１和１１０３ｃｍ＾－１；Ｒｕ（ＴＰＰ）Ｏ２，１     

碘化钠-三苯基膦介导的光氧化还原醛亚胺烷基化

电子给受体(EDA)络合物参与的光氧化还原反应近十年来备受关注.新近发现的碘化钠-三苯基膦-N-羟基邻苯二甲酰亚胺羧酸酯EDA络合物已被用于发展多种净氧化还原中性的光反应.本工作将该EDA络合物用于建立净还原性光反应体系,发展了无需光敏剂的可见光促进的醛亚胺自由基加成反应.该反应不仅能以高产率得到仲、叔、α-杂原子取代...     

竹红菌素的β-腈乙基化和选择光氧化

前文报道了竹红菌素的结构修饰,本文继续报道竹红菌素和丙烯腈的β-腈乙基化反应。     

光氧化反应研究——Ⅷ.苊酮作为电子给体的电子转移光氧化反应机理

研究了苊酮(ANO)在9,10-二氰蒽(DCA)敏化下的光氧化反应与机理。实验发现,该反应具有逐步氧化模式,依次生成1,8-(3′-羟基)-斗-萘内酯和1,8-萘二甲酸酐。通过循环伏安,荧光淬灭和激基络合物检测,DCA/联苯共敏化反应以及CIDNP效应等研究,证明苊酮可以作为电子给体与单线态DCA发生热力学上有利的电子转移过程。     

水溶性稀土卟啉络合物的合成及电化学行为

对水溶性稀土卟啉络合物的合成、结构、稳定性及其电化学特性进行了系统研究，测定了络合物的稳定常数，讨论了稀土卟啉络合物的电极反应机理；对于镧系卟啉络合物，从Ｔｂ到Ｙｂ随着原子序数的递增，重稀土卟啉络合物的稳定性及还原性不断增强，还原峰电位不断正移，并从理论上解释了该规律。     

红紫素-18酰亚胺衍生物的化学修饰

以脱镁叶绿酸-a甲酯为原料, 通过对其3-位乙烯基的氧化, 得到了3-甲酰基脱镁叶绿酸甲酯, 利用Wittig反应合成了对应的3-(2-取代的乙烯基)脱镁叶绿酸甲酯. 结合E环的改造, 将其转变成酸酐环进而转变成N-取代的酰亚胺环. 目标化合物具有亲水区和疏水区两部分, 吸收波长明显向红位移. 合成得到的红紫素-18酰亚胺衍生物有可能成为光动力疗癌的理想光敏剂. 合成的新化合物均由核磁共振、红外光谱、元素分析和质谱予以证实.     

红紫素-18酰亚胺衍生物的合成

以脱镁叶绿酸甲酯为原料, 通过对其3-位乙烯基的氧化, 得到3-(2,2-二甲氧基乙基)-3-去乙烯基脱镁叶绿酸甲酯, 经过甲酸处理得到3-(2-氧代乙基)-3-去乙烯基脱镁叶绿酸甲酯, 选择适当的条件, 通过Grignard 反应合成了对应的3-(2-羟基烷基)-3-去乙烯基脱镁叶绿酸甲酯. 实验结果表明: 3-(2-氧代乙基)-3-去乙烯基脱美叶绿酸甲酯和Grignard试剂的反应, 只要反应条件控制得当, 13²-位的甲氧甲酰基不会脱去. 结合E环的改造, 将其转变成酸酐环进而转变成N-取代的酰亚胺环. 目标化合物的合成也可以将3-(2,2-二甲氧基乙基)-去乙烯基脱镁叶绿酸甲酯转变成N-取代的酰亚胺后, 再和Grignard试剂反应, 完成目标化合物的合成. 合成的一系列化合物具有长波长的紫外吸收. 化合物的结构变化对紫外吸收的影响作了相应的讨论. 合成的新化合物均由核磁共振、红外光谱、元素分析予以证实.     

Dye-sensitized photooxygenation of sugar furans: novel bis-epoxide and spirocyclic C-nucleosides

Dye-sensitized photooxygenation of 2-methyl 5-(2,3,5-tri-O-acetyl-β-d-ribofuranosyl)furoate leads to (1S,4R)-endo-peroxide, highlighting a high facial diastereoselectivity. This endo-peroxide rearranges into syn-(1R,2R:3S,4R)-diepoxide C-nucleoside, while by Et₂S-reduction followed by NEt₃ catalysis affords a spirocyclic C-nucleoside.     

Spiroketals of monosaccharides by dye-sensitized photooxygenation of furyl ketoses

[4+2] Cycloaddition of singlet oxygen to suitably substituted furans followed by reduction of the corresponding endoperoxides afforded functionalized enediones which quickly cyclized into the titled spiroketals. The reported method represents a green synthetic one-pot procedure for novel [6,6]-, [5,6]-, and [5,5]-spiroketals of sugars.     

Photodimerization and photooxygenation of 9-vinylcarbazole catalyzed by titanium dioxide and magnesium perchlorate

<正>Photoreaction of 9-vinylcarbazole in acetonitrile in the presence of titanium dioxide and a catalytic amount of magnesium perchlorate gave 3,6-di(9-carbazolyl)-1,2-dioxane as a photooxygenated product via photodimerization of 9-vinylcarbazole.The photoreaction proceeds via an electron transfer mechanism,where magnesium perchlorate accelerated formation of the photo-oxygenated product.     

Dye-sensitized photooxygenation of sugar-furans as synthetic strategy for novel C-nucleosides and functionalized exo-glycals

The methylene blue-sensitized photooxygenation of β-ribofuranosyl furan 1e followed by in situ Et₂S treatment afforded the conformationally stable β-ribofuranoside 4e almost quantitatively. The latter was converted to pyridazine C-nucleoside 6e by cyclization with NH₂NH₂ and to pyrazoline 7e through a 1,3-dipolar cycloaddition with diazomethane. Attempts to epoxidize the double bond failed both by dimethyldioxirane (DMDO), which left 4e unchanged, and by NEt₃/t-BuOOH or NaOO-t-Bu which respectively afforded the new and unexpected exo-glycals E,Z-8e and the novel furan derivative 9.     

Regioselectivity in the ene-reaction of singlet oxygen with cyclic alkenes: photooxygenation of methyl-substituted 1,4-cyclohexadiene derivatives

The photooxygenation of the 1-methyl-, 2,3-dimethyl-, and 1,4-dimethylcyclohexa-1,4-dienes, which are readily available through Birch reduction, yielded the corresponding ene-products. The formed endocyclic dienes were trapped by the addition of singlet oxygen to give the corresponding bicyclic endoperoxy hydroperoxides. In the case of 1-methylcyclohexa-1,4-diene and 1,4-dimethylcyclohexa-1,4,-diene, the cis-effect determined the product distribution. Photooxygenation of 2,3-dimethylcyclohexa-1,4-dienes gave mainly exocyclic olefin, which was attributed to the lowered rotational barrier of the methyl group and increased reactivity of the methyl groups.     

Deuterium kinetic isotope effects in homogeneous decatungstate catalyzed photooxygenation of 1,1-diphenylethane and 9-methyl-9H-fluorene: evidence for a hydrogen abstraction mechanism

The homogeneous decatungstate catalyzed photooxygenation of 1,1-diphenylethane and 9-methyl-9H-fluorene has been studied mechanistically. The primary and β-secondary kinetic isotope effects provide strong evidence for a stepwise mechanism, with a hydrogen atom abstraction in the rate-determining step.     

Synthesis of branched carbasugars via photooxygenation and manganese(III) acetate free radical cyclization

Transformation of cyclohexa-1,3- and 1,4-dienes to carbasugars is described. Photooxygenation of dienes gave bicyclic endoperoxides, which were reduced with thiourea to the corresponding 1,4-diols with cis-configuration. Lactonization of the remaining double bond by oxidative addition of acetic acid to the double bond in the presence of Mn(OAc)₃ followed by lactone ring-opening reaction gave the target branched carbasugars.     

Formation of 1,2,4-dioxazolidines by electron-transfer photooxygenation of aziridines

DCA-sensitized photooxygenation of $\text{cis}$- and $\text{trans}$-2,3-diphenylaziridine in acetonitrile yields exclusively $\text{cis}$-3,5-diphenyl-1,2,4-dioxazolidine. Photooxygenation of N-alkyl- substituted 2,3-diphenylaziridines provides both isomers of the peroxide. The $\text{cis}$$\text{trans}$ ratio of isomers decreases with increasing size of the group on nitrogen. These stereochemical results provide support for a proposed mechanism involving addition of singlet oxygen to intermediate azomethine ylides.     

Formation of 1,2-dioxanes by electron-transfer photooxygenation of 1,1-disubstituted ethylenes

Electron-rich 1,1-diarylethylenes (1a–e) afford 3,3,6,6-tetraaryl-1,2-dioxanes (3a–e) in high yields (>907%) when subjected to electron-transfer photooxygenation in the presence of DCA. Whereas 1,1-diphenyl-ethylene (1f) and 1,1-di(p-chlorophenyl)ethylene (1h) yield the 1,2-dioxanes 3f and 3h at 30% and less than 10%, respectively, there is negligible (if any) 1,2-dioxane formation with 1,1-di(m-anisyl)ethylene (1i). 1,2-Dioxane formation proceeds in a chain reaction (Scheme 1). N-Vinylcarbazol (1g), however, yields the 1,2-dioxane 3g via the cyclobutane derivative 7 (Scheme 2).