五员碳环、氮环和磷环比较的量子化学研究

用密度泛函(DFT)理论中的B3LYP和从头算(abinitio)理论中UHF,在6-31G基组水平上,对五员碳环、氮环和磷环进行几何优化计算,由所得结果讨论了分子的成键情况,对两类环(一类是C5H5、N5、P5;另一类是C5H5-、N5-和P5-)的相对稳定性分别作比较。结果表明:有机五员碳环比无机五员氮环、磷环稳定,而五员氮环与五员磷环相比,磷环更稳定。     

二茂钛杂环化合物的合成及应用研究进展

钛杂环化合物分子内含有两个碳金属键,是一类重要的有机合成中间体.综述了近年来二茂钛杂三元、四元、五元、六元环化合物的结构特征、合成以及其在有机合成中的应用研究进展,就钛杂环中C—Ti键切断的选择性及反应活性开展了讨论与展望.     

天然萜类分子中部分共轭五员环的内应力与抗肿瘤活性

本文讨论了某些香茶菜属植物中的贝壳杉烯(ent-Kaurene)及 B-闭联贝壳杉烯(B-Seco-Kaurene)等化合物中的α-亚甲基环戊酮、α-亚甲基五员内酯环、α-亚甲基六员内酯环以及含有两个sp~2杂化碳原子的五员环等结构,由于它们具有一定的内应力而导致化合物的化学活性提高,它可能与抗肿瘤活性之间有一定关系。     

异色满并三氮杂 酮化合物的合成

本文选择[1,2,4]三氮杂 酮类的七员环系与异色满并环, 旨在寻找抗癌新药。     

微波促进的杂环化合物合成研究

对微波技术在有机杂环化合物合成研究中的应用做了概述：1)四员杂环;2)五员杂环;3)六员杂环;4)七员杂环;5)大杂环。     

C60的[3＋2]环加成反应

综述了Ｃ６０的［３＋２］环加成反应的研究进展。包括Ｃ６０与亚胺叶立德、重氮化合物、叠氮化合物、氧化腈、腈亚胺、ｃｉｓ－ＨＯＣＨ２ＣＨ＝ＣＨＣＨ２ＯＣＯ２Ｅｔ、１，８－二碘萘、环丙烯酮缩醛和Ｐｙｒａｚｏｌｉｄｉｎｉｕｍ叶立德发生的［３＋２］环加成反应。     

含吡啶环系和中心功能基氮杂冠醚的合成研究

合成了氮杂大环化合物Ⅰ－Ⅳ，并通过＾１Ｈ ＮＭＲ、ＭＳ和元素分析表征了它的结构，对其中间体（７）的合成方法进行了改进，使收率得到了大幅度提高，探讨了在不同温度下的成环反应，结果表明，室温有利于成环和提高反应收率。     

一种氮杂大环铜催化的新型振荡反应

一种氮杂大环铜催化的新型振荡反应宋继梅（合肥地矿部石海局化探中心，，２３００２２）倪诗圣，徐济德（安徽大学化学系，合肥，２３００３９）四氮杂大环铜、镍配合物催化的Ｂｅｌｏｕｓｏｖ－Ｚｈａｂｏｔｉｎｓｋｉｉ反应是一类新型的振荡反应￣［１］，研究这类反应...     

1,3—偶极环加成反应在杂螺环化合物合成中的应用

氧化腈与４，４－亚甲基－１－甲基哌啶的１，３－偶极环加成反应生成了杂螺［４．５］葵烷化合物，反应具有立体专一性．产物经ＬｉＡｌＨ４还原生成了γ－氨基醇，最后经插入Ｃ－１单元扩环生成了新的杂螺［５．５］十一烷化合物     

环氧环己烷的电化学合成

环氧环己烷的电化学合成何俊翔＊周锦成（温州师范学院化学系温州３２５００３）关键词电化学环氧化，环氧环己烷，环己烯，钛基氧化物电极１９９６－１１－２２收稿，１９９７－０６－０５修回间接电解氧化合成环氧化合物的研究已有报道［１～４］．它们均在铂电极上完成...     

Cyclic alkoxyamines for nitroxide‐mediated radical polymerization

A 5‐membered cyclic alkoxyamine and a 17‐membered cyclic alkoxyamine were synthesized and used in the polymerization of styrene. Polymerizations using the 5‐membered cyclic alkoxyamine resulted in polymers with uncontrolled molecular weights and high polydispersities. Polymerizations using the 17‐membered cyclic alkoxyamine produced oligomeric polymers in which multiple polymer chains are linked through NO‐C bonds. EPR homolysis experiments revealed that the 5‐membered cyclic alkoxyamine does not dissociate to form a nitroxide species, even at temperatures as high as 403 K. In contrast, the 17‐membered cyclic alkoxyamine does dissociate to form nitroxide, but the rate of dissociation is slower than that of parent acyclic alkoxyamine 2,2,5‐trimethyl‐3‐(1‐phenylethoxy)‐4‐phenyl‐3‐azahexane. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8049–8069, 2008     

Relative reactivity of three and four membered rings--the absence of charge effect

Radical (neutral) and electrophilic (cationic) ring opening reactions were studied computationally in order to probe the difference in reactivity between three and four membered rings. Using the Marcus equation we have shown that the activation energy for the four membered ring opening is close to the Marcus predicted barrier whereas three membered rings display much higher reactivity than that predicted by the Marcus equation. Thus, the reactivity of the three membered rings is enhanced, in addition to the strain release, by another factor which is not operative in the four membered rings. It is clear also that this factor is not charge dependent. The possible origin of this effect is discussed.     

F-对沸石分子筛双四元环影响的量子化学计算

采用PM3量子化学计算方法研究了沸石分子筛及无机微孔晶体结构中双四元环内含F^-及不含F^-的8种模型簇的几何结构、电子结构以及稳定性,考察了F^-对双四元环结构和性质的影响,发现F^-的存在依次增强了纯硅、磷铝和磷镓双四元环的稳定性,而降低了硅铝的稳定性,F^-在双四元环中所处位置的计算值与实验晶体数据基本吻合.     

Azulene in Polymers and Their Properties

Azulene, a unique isomer of naphthalene, has received much interest from researchers in different fields due to its unusual chemical structure with a negatively charged 5‐membered ring fused with a positively charged 7‐membered ring. In particular, incorporation of azulene into polymers has led to many interesting properties. This minireview covers functionalization methods of azulene at its various positions of 5‐ and 7‐membered rings to form azulene derivatives including azulene monomers, and gives an overview of a wide range of azulene‐containing polymers including poly(1,3‐azulene), azulene‐based copolymers with connectivity at 1,3‐positions of the 5‐membered ring, or 4,7‐positions of the 7‐membered ring, as well as copolymers with azulene units as side chains. Their chemical and physical properties together with applications of azulene‐containing polymers have also been summarized.     

Correlation of ring nitrogen substituents with carbon-13 nuclear magnetic resonance data in azoloazines

Carbon–13 nuclear magnetic resonance data have been acquired on 22 azoloazines. Chemical shifts have been correlated by a step–wise linear multiple regression with nitrogen substituents in both the 5- and 6-membered rings using pyrrolo[1,2-α]pyridine as the reference for chemical shift correlation. The data demonstrate that a highly correlated set of chemical shift parameters exist. Nitrogen substitution in the five–membered ring produces larger cross–ring effects than are oberved in the five–membered ring when substitution occurs in the six–membered ring. Within the six–membered ring a constant para- substituent parameter is noted. The meta- and para- parameters are more complex and fall into two groups for each parameter. Within the five–membered ring, a highly regular chemical shift pattern is observed which reflects an attenuated perturbation from nitrogen substitution in the six–membered ring.     

Ringerweiterungsreaktionen von N-(2-Aminoäthyl)-, N-(4-Aminobutyl)-, N-(6-Amino-4-aza-hexyl)- und N-(8-Amino-4-aza-octyl)-lactamen. 7. Mitteilung über Umamidierungsreaktionen

Ring Enlargement Reactions of N -(2-Aminoethyl)- , N -(4-Aminobutyl)- , N -(6-Amino-4-aza-hexyl)- and N -(8-Amino-4-aza-octyl)-lactames The N-aminoalkyl-lactams 1 , 3 , 4 , 10 (Scheme 2) and 13 (Scheme 3) have been synthesized. In the presence of KAPA (potassium 3-aminopropylamide in 1,3-propanediamine) 1 is stable, whereas 3 , 4 and 10 rearrange under ring enlargement to 5 , 8 and 11 , respectively. The 4-aminobutyl derivate 13 rearranges in a fast reaction to 14 ; after a longer reaction time the 22membered ring 16 and the ring opened product 18 are formed. Hence it may be concluded that the 7membered lactam ring is more stable than the 10membered one, and the 11membered lactam ring is more stable than the 8 membered one. Moreover, the 5- and 6 membered ring intermediates of these transamidation reactions are prefered to the 7membered ring intermediates (cf. [10]).     

Construction of Nitrogen‐Containing 9‐Membered Ring Epoxy Vinyl Ethers via Gold(I)‐Catalyzed Intramolecular Cyclization Reactions of Acyclic 5‐Aza‐2,3‐epoxy‐7‐yn‐1‐ols

A series of substituted nitrogen‐containing 9‐membered epoxy vinyl ethers has been constructed from easily available 5‐aza‐2,3‐epoxy‐7‐yn‐1‐ols. Attack of the hydroxyl group onto the gold(I)‐activated alkyne gave the postulated 9‐membered allylic vinyl ether gold intermediate which underwent protodeauration affording the 9‐membered epoxy vinyl ethers.     

Total Synthesis of Talatisamine

Talatisamine ( 1 ) is a member of the C₁₉‐diterpenoid alkaloid family, and exhibits K⁺ channel inhibitory and antiarrhythmic activities. The formidable synthetic challenge that 1 presents is due to its highly oxidized and intricately fused hexacyclic 6/7/5/6/6/5‐membered‐ring structure (ABCDEF‐ring) with 12 contiguous stereocenters. Here we report an efficient synthetic route to 1 by the assembly of two structurally simple fragments, chiral 6/6‐membered AE‐ring 7 and aromatic 6‐membered D‐ring 6 . AE‐ring 7 was constructed from 2‐cyclohexenone ( 8 ) through fusing an N‐ethylpiperidine ring by a double Mannich reaction. After coupling 6 with 7 , an oxidative dearomatization/Diels–Alder reaction sequence generated fused pentacycle 4 b . The newly formed 6/6‐membered ring system was then stereospecifically reorganized into the 7/5‐membered BC‐ring of 3 via a Wagner–Meerwein rearrangement. Finally, Hg(OAc)₂ induced an oxidative aza‐Prins cyclization of 2 , thereby forging the remaining 5‐membered F‐ring. The total synthesis of 1 was thus accomplished by optimizing and orchestrating 33 transformations from 8 .     

[N‐(Carboxyl­ato­methyl)­aspartato(3–)](ethyl­enedi­amine)­cobalt(III) trihydrate

The mononuclear title complex, [Co(C₆H₆NO₆)(C₂H₈N₂)]·3H₂O, contains an octahedrally coordinated Co^III atom. The N‐(carboxy­methyl)­aspartate moiety is coordinated as a tetradentate ligand, providing an OONO‐donor set and forming two trans five‐membered chelate rings and one six‐membered chelate ring. A seven‐membered chelate ring is also formed, which consists of part of the six‐membered chelate ring and part of one of the five‐membered chelate rings. The crystal structure of the complex is stabilized by hydrogen bonds with three water mol­ecules.     

Hydrolysis of cyclic phosphoramides. Evidence for syn lone pair catalysis

Hydrolysis between 1.5 < pH < 4 of five and six membered cyclic phosphoramides has been followed by UV and 3'PNMR spectroscopy. The observed rates fit the equation: k(obs) = k(H2O) [H+]/([H+] + Ka) + k'(H2O), where k(H2O) and k'(H2O) are the pseudo first-order rate constants of water attack on the protonated phosphoramide and its unprotonated form, respectively, and Ka is the phosphoramide acidity equilibrium constant. Although, faster hydrolysis rates on the five membered ring are expected due to the energy released in going from a strained cyclic to a "strained free" trigonal-bipyramidal-pentacoordinated intermediate, with one of the cyclic nitrogens occupying the apical position. these compounds react slightly faster (k(H2O) values) but slower regarding the k'(H2O) values than the six membered analogs. The balance in reactivity is attributed to the additional stability obtained in the six membered cyclic compounds by a syn orientation of the two lone pairs of the cyclic nitrogen to the water attack. This stabilization does not exist in the five membered phospholidines since the water attack is perpendicular to the electron pairs of the cyclic nitrogen. In agreement with the incoming water orientation, the product ratios from the hydrolysis show that in the five membered rings the main product is the one produced by endocyclic cleavage; meanwhile, in the six membered cyclic phospholines the kinetic product is the one produced by exocyclic cleavage. The syn orientation of two electron pairs on nitrogen stabilizes the transition state of water approach to the phosphoramides by ca. 3 kcal mol(-1) when compared to the orthogonal attack.