- Photoredox-Catalyzed Cascade Radical Cyclization of Ester Arylpropiolates with CF3SO2Cl to Construct 3-Trifluoromethyl Coumarin Derivatives
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We report a highly efficient method to construct 3-trifluoromethyl coumarins using CF3SO2Cl as the trifluoromethyl radical source with ester 3-arylpropiolates. The reaction incorporated a cascade cyclization/dearomatization/ester mig
- Chen, Long,Wu, Lianlian,Duan, Weijie,Wang, Tao,Li, Letian,Zhang, Keke,Zhu, Jingmei,Peng, Zhi,Xiong, Fei
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- Chlorinative Cyclization of Aryl Alkynoates Using NCS and 9-Mesityl-10-methylacridinium Perchlorate Photocatalyst
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In a chlorinative cyclization, Mes-Acr-MeClO4 acted as a visible-light photocatalyst to obtain 3-chlorocoumarins from aryl alkynoates and N-chlorosuccinimide (NCS). The radical initiated reaction proceeded in a cascading manner via Cl- addition to alkynoa
- Pramanik, Milan,Mathuri, Ashis,Sau, Sudip,Das, Monojit,Mal, Prasenjit
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supporting information
p. 8088 - 8092
(2021/10/12)
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- Cyclization of aryl 3-aryl propynoates into 4-arylcoumarins catalyzed by cyclometalated Platinum(II) complexes
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Cyclometalated (ppy)PtII complexes (ppy = 2-phenylpyridinato-C2,N) catalyze the intramolecular cyclization of aryl propynoates to form coumarins and benzocoumarins. The complex [(ppy)PtCl(MeCN)] (5 mol %) was the most active and effi
- Zaitceva, Olesia,Bénéteau, Valérie,Ryabukhin, Dmitry S.,Eliseev, Ivan I.,Kinzhalov, Mikhal A.,Louis, Benoit,Vasilyev, Aleksander V.,Pale, Patrick
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supporting information
(2020/03/05)
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- Atom Transfer Oxidative Radical Cascade of Aryl Alkynoates towards 1,1-Dichalcogenide Olefins
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An oxidative trifunctionalization of aryl alkynoates has been devised via the chalcogenide radical triggered intramolecular 1,4-aryl migration/decarboxylation cascade to prepare 1,1-dichalcogenide tetrasubstituted alkenes in high yields (up to 98 %). This operationally simple reaction proceeds under metal-free conditions, can be executed on gram scale, and highlights formal 1,1-difunctionalization of alkynes. Synthetic potential of this protocol was demonstrated through a twofold cascade rearrangement to access highly conjugated tetra-selenylated alkenes along with a cross-dehydrogenative annulation to prepare fluorene derivative.
- Sahoo, Harekrishna,Ramakrishna, Isai,Mandal, Anup,Baidya, Mahiuddin
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p. 4549 - 4552
(2019/07/31)
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- Visible-light photoredox catalyzed cyclization of aryl alkynoates for the synthesis of trifluoromethylated coumarins
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A strategy for the synthesis of coumarin derivatives via visible-light photoredox catalysis has been developed using fac-Ir(ppy)3 as the photocatalyst under mild conditions. Trifluoromethanesulfonyl chloride is utilized as the trifluoromethylat
- Bu, Mei-jie,Lu, Guo-ping,Cai, Chun
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- Visible-light-mediated radical cascade reaction: Synthesis of 3-bromocoumarins from alkynoates
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A visible-light-mediated radical addition of alkynoates to generate 3-bromocoumarins by using N-bromosuccinimide as the bromo source has been accomplished. This procedure provides a bromo radical addition/spirocyclization/ester migration cascade reaction
- Feng, Shangbiao,Li, Jinlai,Liu, Zaimin,Sun, Haiyu,Shi, Hongliang,Wang, Xiaolei,Xie, Xingang,She, Xuegong
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supporting information
p. 8820 - 8826
(2017/11/03)
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- Visible-Light-Promoted Dual C-C Bond Formations of Alkynoates via a Domino Radical Addition/Cyclization Reaction: A Synthesis of Coumarins
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A visible-light-promoted, mild, and direct difunctionalization of alkynoates has been accomplished. This procedure provides a new strategy toward synthesis of the coumarin core structure by photoredox-mediated oxidation to generate the α-oxo radical, whic
- Feng, Shangbiao,Xie, Xingang,Zhang, Weiwei,Liu, Lin,Zhong, Zhuliang,Xu, Dengyu,She, Xuegong
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supporting information
p. 3846 - 3849
(2016/08/16)
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- Synthesis of 3-Sulfenylated Coumarins: BF3·Et2O-Mediated Electrophilic Cyclization of Aryl Alkynoates Using N-Sulfanylsuccinimides
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A simple and efficient metal-free sulfenylation/cyclization of aryl alkynoates has been developed, obtaining various 3-sulfenylated coumarins in moderate to excellent yields. In the presence of BF3·Et2O, the stable and readily access
- Gao, Wen-Chao,Liu, Tao,Zhang, Bing,Li, Xing,Wei, Wen-Long,Liu, Qiang,Tian, Jun,Chang, Hong-Hong
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p. 11297 - 11304
(2016/11/29)
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- Visible-light initiated oxidative cyclization of phenyl propiolates with sulfinic acids to coumarin derivatives under metal-free conditions
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A visible-light initiated oxidative cyclization of phenyl propiolates with sulfinic acids has been developed. The arylsulfonylation of alkynes was performed at room temperature under metal-free conditions to generate coumarin derivatives with wide functio
- Yang, Wenchao,Yang, Shuai,Li, Pinhua,Wang, Lei
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supporting information
p. 7520 - 7523
(2015/05/04)
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- New Method for Preparation of Coumarins and Quinolinones via Pd-Catalyzed Intramolecular Hydroarylation of C-C Triple Bonds
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A new and general method has been developed for preparation of coumarins and quinolinones by intramolecular hydroarylation of alkynes. Various aryl alkynoates and alkynanilides undergo fast intramolecular reaction at room temperature in the presence of a
- Jia, Chengguo,Piao, Dongguo,Kitamura, Tsugio,Fujiwara, Yuzo
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p. 7516 - 7522
(2007/10/03)
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- 6-Endo-Dig vs. 5-Exo-Dig Ring Closure in o-Hydroxyaryl Phenylethynyl Ketones. A New Approach to the Synthesis of Flavones and Aurones
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The aryl phenylpropynoates 3a-c, prepared by esterification of phenylpropynoic acid with the corresponding phenols, by means of N,N'-dicyclohexylcarbodiimide, give upon irradiation the o-hydroxyaryl phenylethynyl ketones 4a-c.The cyclization of these compounds in basic media follows two alternative pathways: 6-endo-dig ring closure, to give the flavones 8a-c, and /or 5-exo-dig ring closure , to give the aurones 9a-c.The predominance of one or the other cyclization mode is strongly influenced by the reaction conditions.Thus, the use of potassium carbonate in acetoneas cyclizing reagent favors the 6-endo-dig process, while the 5-exo-dig process becomes clearly enhanced when using sodium ethoxide or potassium carbonate in ethanol.The mechanistic implications of these facts are discussed within the framework of Baldwin's rules.From the preparative point of view, the above results disclose the synthetic possibilities of the key ketones 4 as precursors of flavones and aurones.
- Garcia, Hermenegildo,Iborra, Sara,Primo, Jaime,Miranda, Miguel A.
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p. 4432 - 4436
(2007/10/02)
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