- Synthesis of Vinylnaphthofurans and NMR Analysis of their Photoswitching
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An easy synthesis of photochromic vinylnaphthofurans by the acid-catalyzed one-pot reaction of naphthols with but-2-yne-1,4-diols is described. These uncolored polyaromatic compounds are activated by UV light, at room temperature, and converted through a stilbene-type electrocyclization into a thermally stable orange species, which can be switched back using visible light. The behavior of these photoswitches was elucidated using NMR, which allowed to identify the photoisomers and some side-products, formed after prolonged UV irradiation.
- Gra?a, Vania,Berthet, Jér?me,Sousa, Céu M.,Delbaere, Stephanie,Coelho, Paulo J.
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- Rhodium-Catalyzed Arylative Transformations of Propargylic Diols: Dual Role of the Rhodium Catalyst
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Controllable synthesis of a variety of allenic alcohols and 2,5-dihydrofurans by rhodium(I)-catalyzed arylative transformations of propargylic diols is reported. The hydroxorhodium catalyst was found to play dual role: it catalyzed the arylation/dehydroxylation reaction of propargylic diols to afford allenic alcohols, and besides, it could convert to a cationic rhodium species in situ, which catalyzed the intramolecular hydroalkoxylation of allenic alcohols to form dihydrofurans. Remarkably, generation of the cationic rhodium species is dependent on the arylboron reagent used. Thus, the controllable synthesis is achieved by simply changing the arylboron reagent. (Figure presented.).
- Xing, Junhao,Zhu, Yong,Lin, Xiao,Liu, Na,Shen, Yue,Lu, Tao,Dou, Xiaowei
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supporting information
p. 1595 - 1599
(2018/03/01)
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- Regioselective rapid synthesis of fully substituted 1,2,3-triazoles mediated by propargyl cations
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Regioselective rapid triazole syntheses at low temperature are described. Organic azides and propargyl cations generated by acids gave fully substituted 1H-1,2,3-triazoles. Most reactions could be performed in 5 min at not only rt but also -90 C. Both terminal and internal alkynes were acceptable, and the sterically bulky substituents could afford the products smoothly. Various types of three-component coupling reactions were demonstrated, and the presence of allenylaminodiazonium intermediates was indicated.
- Zhang, Huan,Tanimoto, Hiroki,Morimoto, Tsumoru,Nishiyama, Yasuhiro,Kakiuchi, Kiyomi
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supporting information
p. 5222 - 5225
(2013/11/06)
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- Synthesis of five- and six-membered dihalogenated heterocyclic compounds by electrophile-triggered cyclization
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Highly substituted dihalogenated dihydrofurans, dihydropyrroles, and dihydro-2H-pyrans bearing alkyl, vinyl, aryl, and heteroaryl moieties can be prepared in good to excellent yields (up to 99%) by allowing 1,4-butyne-diol, 4-aminobut-2-yn-1-ol, and pent-2-yne-1,5-diol derivatives to react with different electrophiles (I2, IBr, and ICl) at room temperature. Both halogen atoms generated from electrophiles were used effectively. The resulting halides can be further exploited by using palladium-catalyzed coupling reactions. The presence of trace amount of water is essential for this electrophilic cyclization.
- Ji, Ke-Gong,Zhu, Hai-Tao,Yang, Fang,Shaukat, Ali,Xia, Xiao-Feng,Yang, Yan-Fang,Liu, Xue-Yuan,Liang, Yong-Min
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supporting information; experimental part
p. 5670 - 5678
(2010/11/05)
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