- Practical synthesis of photochromic diarylethenes in integrated flow microreactor systems
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An effective method for the synthesis of photochromic diarylethenes through the generation of heteroaryllithiums and subsequent reaction with octafluorocyclopentene has been developed by using integrated flow microreactor systems. Reactions can be conducted without using cryogenic conditions by virtue of effective temperature and residence time control, although much lower temperatures (-1. Therefore, the present integrated flow microreactor method serves as a practical way of synthesizing various photochromic diarylethene derivatives. Too successful to be cool: An effective method for the synthesis of photochromic diarylethenes has been developed by using integrated flow microreactor systems. Reactions can be conducted without the need for cryogenic conditions by using these systems (see picture). The synthesis of unsymmetrical diarylethenes, which is difficult to achieve by using conventional macro batch systems, has also been accomplished. Copyright
- Asai, Tatsuro,Takata, Atsushi,Nagaki, Aiichiro,Yoshida, Jun-Ichi
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experimental part
p. 339 - 350
(2012/06/30)
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- Practical iron-catalyzed dehalogenation of aryl halides
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An operationally simple iron-catalyzed hydrodehalogenation of aryl halides has been developed with 1 mol% Fe(acac)3 and commercial t-BuMgCl as reductant. The mild reaction conditions (THF, 0 °C, 1.5 h) effect rapid chemoselective dehalogenation of (hetero)aryl halides (I, Br, Cl) and tolerate F, Cl, OR, SR, CN, CO2R, and vinyl groups.
- Czaplik, Waldemar Maximilian,Grupe, Sabine,Mayer, Matthias,Wangelin, Axel Jacobi Von
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experimental part
p. 6350 - 6352
(2010/10/03)
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- Thermally Irreversible Photochromic Systems. Reversible Photocyclization of 2-(1-Benzothiophen-3-yl)-3-(2 or 3-thienyl)maleimide Derivatives
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Non-symmetric diarylethenes that have a 1-benzothiophene ring on one end and a 2-thienyl or 3-thienyl group on the other end of the double bond of maleimide were synthesized in order to study the effects of the substitution position of the thiophene ring on the absorption bands and the reactivities. The open-and closed-ring forms of N-cyanomethyl-2-(2, 4-dimethyl-5-phenyl-3-thienyl)-3-(2-methoxy-1-benzothiophen-3-yl)maleimide showed absorption bands at 420 and 563 nm in hexane, respectively. When 3-thienyl was changed to 2-thienyl, the absorption bands of N-cyanomethyl-2-(3,4-dimethyl-5-phenyl-2-thienyl)-3-(2-methoxy-1-benzothiophen- 3-yl)maleimide shifted to 448 nm (the open-ring form) and 487 nm (the closed-ring form), respectively. The cyclization and ring-opening quantum yields were also dependent on the substitution position. The cyclization yield decreased from 0.30 to 0.03 by changing the position from 3- to 2-thienyl, while the ring-opening yield increased from 0.03 to 0.13. No absorption spectral change by photoirradiation was observed for N-cyanomethyl-2,3-bis(3,4-dimethyl-5-phenyl-2-thienyl)maleimide, which has two 2-thienyl groups.
- Uchida, Kingo,Kido, Yuichi,Yamaguchi, Tadatsugu,Irie, Masahiro
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p. 1101 - 1108
(2007/10/03)
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- Photochromism of Dithienylethenes with Electron-Donating Substituents
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Bis(2,4-dimethyl-5-phenylthiophene-3-yl)perfluorocyclopentenes having hydrogen, methoxy, diethylamino, or cyano substituents at para-positions of the phenyl groups were synthesized to reveal the effect of the substitution on the absorption coefficient ε of the closed-ring forms and the photochemical reactivity.Electron-donating substituents, such as methoxy or diethylamino groups, were found to be effective to increase the absorption coefficient and to decrease the ring-opening quantum yield.The cyclization quantum yield was scarely affected by the substitution.The conversion from the open- to the closed-ring forms of the diethylamino-substituted compound in the photostationary state under irradiation with 313 nm light was close to 100percent.
- Irie, Masahiro,Sakemura, Kazuyuki,Okinaka, Masakazu,Uchida, Kingo
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p. 8305 - 8309
(2007/10/03)
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