Photochemical properties and the structure of 6-methyl-2,4-diphenyl-1-(p-tolyl)pyrimidinium perchlorate and the product of its photocyclization

The structure and photochemical properties of 6-methyl-2,4-diphenyl-1-(p-tolyl)pyrimidinium perchlorate (1) and 4,8-dimethyl-2-phenylpyrimido[1,2-f]phenanthridinium (2) formed as a result of photocyclization of1 have been studied. The crystal structure of compound1 has been studied at –140 °C and 25 °C. In cation1, theN-tolyl substituent and -Ph ring are noncoplanar with the pyrimidinium fragment (the angles are 67.9° and 41.1°, respectively), while the angle between the -Ph ring and the pyrimidinium moiety is only 7.1° (–140 °C). The photocyclization product2 has a flattened structure.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1731–1735, September, 1995.This work was partly (studies performed at Scientific Research Institute of Physical and Organic Chemistry at Rostov State University) supported by the Science Foundation Russian Universities.     

Vilsmeier—Haack reaction of methyl lambertianate and non-sensitized photocyclization of the resulting product

Vilsmeier—Haack formylation of methyl lambertianate results in its 16-formyl derivative as the predominant product, which readily enters the intramolecular reaction of photochemical [2+2]-cycloaddition in the absence of a sensitizer.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2514–2517, December, 1995.     

Photocyclodehydrofluorination

Mallory‐type photocyclization involves a series of photoreactions of stilbenes, o‐terphenyls and related derivatives, which undergo intramolecular cyclization via dihydrophenanthrene intermediates. In typical Mallory photocyclizations, oxidants are usually needed to produce the final phenanthrene‐containing product. In the research described here, appropriately fluorinated stilbenes and o‐terphenyls undergo ring closure and HF is eliminated. This photocyclodehydrofluorination (PCDHF) reaction is very useful to produce a wide range of selectively fluorinated polynuclear aromatic hydrocarbons that possess a phenanthrene (or heterocyclic analogue of phenanthrene) substructure. These fluorinated products are of great interest in various aspects of the materials science.     

Synthesis of chrysenosiloles via Mallory photocyclization

Development of synthetic methods for silole-containing or –fused polycyclic aromatic compounds has been in great demand. Described in this paper is an easy synthetic method for the high-efficient synthesis of chrysenosilole derivatives from silatricyclic compounds via the Mallory photocyclization reaction. It is noteworthy that those conventional transition-metal and Lewis acid catalyzed or mediated CC bond coupling reactions did not work well for this aryl-aryl coupling reaction.     

Synthesis,Electronic Properties,and Reactivity of Phospholes and 1,1′‐Biphospholes Bearing 2‐ or 3‐Thienyl C‐Substituents

PS, I love you! Novel mixed phosphole/thiophene π‐conjugated systems were synthesized and their electronic properties have been studied both experimentally by UV/Vis spectroscopy and electrochemistry and by theoretical calculations. Exploiting the chemistry of both P‐ and S‐heteroles allows the generation of a diverse range of novel ring‐fused benzophosphole–thiophene derivatives.

     

非共轭双发色团体系的光化学（Ⅱ）──长链双香豆素的光环化反应和荧光光谱研究

报道双（４－甲基－７－香豆素基）氧乙酸多亚甲基二醇酯的合成、光环化反应和荧光光谱研究。结果表明，双（４－甲基－７－香豆素基）氧乙酸多亚甲基二醇酯在氯仿溶液中于光照下生成分子内环化产物，环化产物的产率随着链长的增加而逐渐降低，这与荧光光谱中观察到的相对荧光强度随链长增加而增大的整体趋势一致。     

Characterization and photophysical properties of sulfur-oxidized diarylethenes

Controlled oxidation of sulfur atoms in benzothiophene rings of a photochromic diarylethene, 1,2-bis(2-methyl-1-benzothiophene-3-yl)perfluorocyclopentene (BTF6) by 3-chloroperbenzoic acid afforded various oxidation products such as BTFO1, BTFO2, and BTFO4. Upon irradiation with UV light, colorless o-BTFO1 and o-BTFO2 turned to red color, whereas colorless o-BTFO4 turned to yellow color. Theoretical calculation was performed to understand the absorption spectra of closed-ring isomers. All of those compounds returned back to their open-ring isomers upon irradiation with visible light. The cyclization conversions of BTFOn (n=1, 2, and 4) at the photostationary state are higher than that of BTF6. Interestingly, in the case of BTFO1, because of the unsymmetrical environment around the sulfoxide subunit in the molecule, the diastereoselective photocyclization was observed in 25% de. In addition, c-BTFO2 and c-BTFO4 also exhibited a marked fatigue resistance and strong fluorescence, respectively. Oxidation state of sulfur atom in a diarylethene can play an important role in determining its photophysical and photochromic properties.     

One-quantum process of formation oftrans-1,2-di(2-naphthyl)ethylene under photolysis of 4a, 4b-dihydrodibenzphenanthrene

Thetrans-isomer of 1,2-di(2-naphthyl)ethylene is formed along with thecis-isomer in the one-quantum process under irradiation at the wavelength corresponding to the long-wave absorption band of 4a,4b-dihydrodibenzphenanthrene. The quantum yields of the photoinitiated processes were measured. The adiabatic mechanism was suggested for the photoinitiated ring opening in 4a, 4b-dihydrodibenzphenanthrene. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2366–2368, November, 1998.     

First total syntheses of the 1,2,3,4-tetrahydronaphtho[2,1-f]isoquinolines annoretine and litebamine

We describe here the first total synthesis of the two natural 1,2,3,4-tetrahydronaphtho[2,1-f]isoquinolines, annoretine and litebamine, from [2-(2-styrylphenyl)ethyl]methylcarbamic acid ethyl esters. The key steps were the Bischler-Napieralski cyclization to form the isoquinoline unit and photocyclization of the resulting 2-methyl-5-styryl-3,4-dihydro-2H-isoquinolin-1-ones to 2-methyl-3,4-dihydro-2H-naphtho[2,1-f]isoquinolin-1-ones.     

Photochromic dihetarylethenes

1,2-Bis[2-methyl-5-(benzoxazol-2-yl)thien-3-yl]hexafluorocyclopentene was synthesized, and its photochronic properties were studied For Part 2, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1011–1014, May, 1999.