带取代基硝酮化合物光环化反应的研究

本工作合成了一系列取代的硝酮类化合物。其中部分化合物仅一侧的苯环上带有取代基,而另部分化合物则两个苯环上均带有取代基。研究工作表明:取代基处于一侧的硝酮类化合物,不论取代基是给出电子或接受电子的,均有利于化合物光环化反应的进行。而当两个苯环分别带有给电子及接受电子的取代基形成推拉结构时,则大大减弱了化合物光环化反应的发生。文章对上述结果进行了初步讨论。     

From Overcrowded Polycyclic Aromatic Enes to Semifullerenes

Abstract

Overcrowded polycyclic aromatic enes (1), e.g., bi-9H-fluoren-9-ylidene (2) and bi-4H-cyclopenta[def]-phenanthren-4-ylidene (3) are potential starting materials for the preparation of bowl-shaped fragments of fullerenes. Semiempirical MNDO-PM3 calculations of C₂₆ H_n and C₃₀ H_n (n = 12,14,16) species 2–14 are used to analyze energetic and steric effects on the dehydrocyclization and isomerization reactions of these molecules. the out-of-plane bending and pyramidalization in these species are ascribed to intramolecular overcrowding in the fjord and cove regions and to strain introduced by C5 rings in the PAH skeleton. Oxidative photocyclization reactions on Z-2,2′-bridged derivatives of 2 and 3 are briefly outlined.     

（4－N，N－二甲氨基）－苯基－N－苯基硝酮在高聚物薄膜中光化学反应特性的研究

本工作测定了（４－Ｎ，Ｎ－二甲氨基）－苯基－Ｎ－苯基硝酮（ＤＭＡＰＮ）在不同介质中光照后折射率的变化，发现其折射卒随光照时间的增长而明显降低。工作研究了ＤＭＡＰＮ在高分子薄膜内的光化学反应与高聚物分子量的关系，在分子量较低的区域，高分子介质对小分子反应的影响是不规则的，而在高分子量区，则随着分子量的增大，反应速率下降，对所得的结果进行了初步讨论．     

From Overcrowded Polycyclic Aromatic Enes to Semifullerenes

Bi-9H-fluoren-9-ylidene (2) and bi-4H-cyclopenta[def]phenanthren-4-ylidene (5) are potential starting materials for the preparation of bowl-shaped fragments of fullerenes. Semiempirical MNDO-PM3 calculations of C₂₆H_n and C₃₀H_n (n = 12, 14, 16) species 2-12 are used to analyze energetic effects on the dehydrocyclization and isomerization reactions of these species. Oxidative photocyclizations on Z-2,2′-bridged derivatives of 2 and 5 are briefly outlined.     

A Hexahelicene,Racemization-resistant below 300°C. Synthesis,Conformation and Racemization Parameters of 1, 3-Di-tert-Butylhexahelicene

1,3-Di-tert-butylhexahelicene 1 was synthesized in 95% yield by irradiation of 2-(3,5-di-tert-butylstyryl)-benzo[c]phenanthrene in hexane in the presence of iodine under anaerobic conditions. NMR-spectroscopy, X-ray analysis and force-field calculations give a consistent picture of the spatial structure of 1 in solution and in the solid phase. Partial resolution of the mixture of enantiomers was performed by chromatography over silicagel, coated with TAPA. The enantiomers of 1 are very resistant to racemization, which occurs only with a detectable rate at temperatures above 300°C. Racemization parameters reveal a high enthalpy and in contrast to other helicenes a positive entropy of activation. The mechanism of the racemization is discussed.     

4,11-BISANTHENEQUINONE AND 10,10′-BIANTHRONE: SIMPLE ONE-STEP SYNTHESES FROM ANTHRONE

Irradiation of a dichloromethane/benzene solution of anthrone and molecular bromine promotes a cascade of events that continues all the way to 4,11-bisanthenequinone, which precipitates as a yellow solid from the solution as it is formed. Alternatively, treatment of anthrone in the dark with molecular iodine and diazabicyclo[5.4.0]undecene (DBU) at room temperature in dichloromethane gives 10,10′-bianthrone. These new procedures represent particularly convenient methods for preparing the title compounds, each in just one step from commercially available anthrone. Diprotonation of 4,11-bisanthenequinone with triflic acid in CDCl₃ generates a red solution of the dication, the ¹H NMR spectrum of which is reported here for the first time: δ (ppm) 10.00 (d, J = 8.0 Hz, 4 H), 9.82 (d, J = 8.0 Hz, 4 H), 8.76 (t, J = 8.0 Hz, 4 H).     

A Tandem Photochemical Approach for the Synthesis of Biologically Important Metabolites of Benzo[b]fluoranthene

A new photochemical approach for the synthesis of various metabolites of benzo[b]fluoranthene has been investigated, involving an oxidative photocyclization reaction of substituted cis-stilbenes to form the phenanthrene moiety, and an intramolecular photoarylation to generate the five-membered ring system. This methodology allowed a highly convergent synthesis of various benzo[b]-fluoranthene metabolites including those with an additional phenol group in the peninsular ring.     

基于meso-位置含有S原子的醌式Bisanthene衍生物的合成与性质表征

在醌式Bisanthene的meso-位置嵌入杂原子S,然后对其光电性质进行研究。原料9-噻吨酮和劳森试剂反应得到硫酮(Ⅲ),接着和水合肼缩合成酮腙(Ⅳ),其后被氧化得到相应的重氮化合物,该产品直接和Ⅲ通过Barton-Kellogg反应制备环硫化合物Ⅴ,接着被Cu粉还原生成烯烃前体Ⅵ。最后对Ⅵ进行Katz-modified Mallory光关环来合成Ⅰ。由于单边关环产物Ⅶ不具有均苯乙烯类结构骨架,不能进一步发生光关环得到目标产物Ⅰ。化合物Ⅶ和Ⅵ相比,表现出扩展的π体系,自身的最大吸收波长红移105 nm,发射波长红移90 nm。另外,电化学测试表明Ⅶ可以被可逆的氧化为阳离子,且被扩展的π体系所稳定。由此推测,目标产物I具有更大的π体系,更长范围的吸收及发射波长,较低的Eg、更多级的可逆氧化电位。     

Synthesis,Photochemistry, Computational Study and Potential Application of New Styryl-Thiophene and Naphtho-Thiophene Benzylamines

In this research, the synthesis, photochemistry, and computational study of new cis- and trans-isomers of amino-thienostilbenes is performed to test the efficiency of their production and acid resistance, and to investigate their electronic structure, photoreactivity, photophysical characteristics, and potential biological activity. The electronic structure and conformations of synthesized thienostilbene amines and their photocyclization products are examined computationally, along with molecular modeling of amines possessing two thiophene rings that showed inhibitory potential toward cholinesterases. New amino-styryl thiophenes, with favorable photophysical properties and proven acid resistance, represent model compounds for their water-soluble ammonium salts as potential styryl optical dyes. The comparison with organic dyes possessing a trans-aminostilbene subunit as the scaffold shows that the newly synthesized trans-aminostilbenes have very similar absorbance wavelengths. Furthermore, their functionalized cis-isomers and photocyclization products are good candidates for cholinesterase inhibitors because of the structural similarity of the molecular skeleton to some already proven bioactive derivatives.     

2,9-Dimethylpicene: Synthesis,Mutagenic Activity,and Identification in Natural Samples

2,9-Dimethylpicene (2,9-DMPic) has been conveniently synthesized via a new route involving oxidative photocyclization of suitable substituted diarylethylenes and has been characterized by high-resolution 400-MHz ¹H-NMR spectroscopy. Furthermore, 2,9-DMPic exhibits a typical line narrowed emission spectrum in n-decane matrix frozen at 15 K (Shpol'skii effect). Its unambiguous identification in a natural sample has been performed by this technique, providing strong evidence for the formation of this compound through aromatization of triterpenoid natural precursors. The mutagenicity of this naturally occurring methylated polycyclic aromatic hydrocarbon (PAH) has been examined in six his ^? strains of Salmonella typhimurium (TA 97, TA 98, TA 100, TA 102, TA 104, TA 1537) in the presence of a hepatic xenobiotic-metabolizing system. While carcinogenic PAH, used as positive controls, showed potent effects in this system, 2,9-DMPic proved completely inactive.