- Decatungstate as Direct Hydrogen Atom Transfer Photocatalyst for SOMOphilic Alkynylation
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A versatile approach for the alkynylation of a variety of aliphatic hydrogen donors, including alkanes, is reported. We used tetrabutylammonium decatungstate as photocatalyst to generate organoradicals from C-H/Si-H bonds via hydrogen atom transfer. The l
- Capaldo, Luca,Ravelli, Davide
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p. 2243 - 2247
(2021/04/05)
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- Photochemical Functionalization of Heterocycles with EBX Reagents: C?H Alkynylation versus Deconstructive Ring Cleavage**
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The development of novel methodologies for the functionalization of saturated heterocycles is highly desirable. Herein, we report a cheap and efficient photochemical method for the C?H functionalization of saturated O-heterocycles, as well as the deconstructive ring-cleavage of S-heterocycles, employing hypervalent iodine alkynylation reagents (ethynylbenziodoxolones, EBX). This photochemical alkynylation is performed utilizing phenylglyoxylic acid as the photoinitiator, leading to the corresponding products in good to high yields, under household fluorescent light bulb irradiation. When O-heterocycles were employed, the expected α-C?H alkynylation took place. In contrast, oxidative ring-opening to form a thioalkyne and an aldehyde was observed with S-heterocycles. Preliminary mechanistic experiments are presented to give first insights into this puzzling divergent reactivity.
- Voutyritsa, Errika,Garreau, Marion,Kokotou, Maroula G.,Triandafillidi, Ierasia,Waser, Jér?me,Kokotos, Christoforos G.
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p. 14453 - 14460
(2020/10/12)
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- Visible-Light-Induced Alkynylation of α-C–H Bonds of Ethers with Alkynyl Bromides without External Photocatalyst
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A direct alkynylation of C(sp3)–H bonds adjacent to an oxygen atom of ethers under visible light irradiation was developed in the absence of an external photocatalyst. The reaction of ethers and alkynyl bromides underwent smoothly to generate the corresponding products in good yields with excellent functional-group tolerance. Initial mechanistic experimental results indicated that the reaction may involve a free radical pathway.
- Xie, Xiaofei,Liu, Jie,Wang, Lei,Wang, Min
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p. 1534 - 1538
(2019/09/06)
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- Ag/P-Stereogenic Phosphine-Catalyzed Enantioselective 1,3-Dipolar Cycloadditions: A Method to Optically Active Pyrrolidines
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A Ag/P-stereogenic phosphine-complex-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with electron-deficient olefins is reported. In this reaction, highly functionalized pyrrolines with a spiro-quaternary stereogenic center were obtained in good yields (up to 99%) with excellent levels of diastereo-(up to >20:1 dr) and enantioselectivities (up to >99% ee). The chirality of adducts was controlled predominantly by the P-stereogenic phosphines.
- Zhi, Mengna,Gan, Zhenjie,Ma, Rong,Cui, Hao,Li, Er-Qing,Duan, Zheng,Mathey, Fran?ois
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supporting information
(2019/05/07)
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- Synthesis of 1,3-dioxacyclan-2-yl-substituted 1,2,3-triazoles
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A new method for preparing 4-(1,3-dioxacyclan-2-yl)-5-phenyl-1,2,3-triazoles in 30–75% yields has been developed on the basis of azide–alkyne cycloaddition to 2-phenylethinyl-1,3-dioxacyclanes. It has been shown that the best results are achieved when the reaction is carried out at 150–155°C in DMSO.
- Zlotskii,Raskil’dina,Golovanov,Bormotin,Bekin
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- Metal-free alkynylation of α-C-H bonds of ethers with ethynylbenziodoxolones
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A metal-free direct alkylation of C-H bonds adjacent to an oxygen or nitrogen atom was developed. This reaction occurred between saturated heterocycles and ethynylbenziodoxolones under mild conditions. A series of 2-alkynyl cyclic alkanes that contain oxygen or nitrogen atoms were prepared in moderate to good yields. This journal is
- Zhang, Ruo-Yi,Xi, Long-Yi,Zhang, Lei,Liang, Shuai,Chen, Shan-Yong,Yu, Xiao-Qi
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p. 54349 - 54353
(2015/02/02)
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- KOAc-promoted alkynylation of α-C-H bonds of ethers with alkynyl bromides under transition-metal-free conditions
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A novel KOAc-promoted α-position C-H activation and alkynylation of ethers with alkynyl bromides to 2-alkynyl ethers has been developed under transition-metal-free and simple reaction conditions. In addition, this methodology can also be extended to the vinylation of ethers with vinyl bromides in excellent regio- and stereo-selectivity. A wide range of direct C(sp)-C(sp3) and C(sp2)-C(sp3) bonds has been formed through this protocol, which offers a new and alternative route. This journal is the Partner Organisations 2014.
- Zhang, Jiajun,Li, Pinhua,Wang, Lei
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p. 2969 - 2978
(2014/05/06)
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- (-)-8-Amino menthol-derived perhydrobenzoxazines as chiral templates and masked aldehydes in the diastereoselective intermolecular Pauson-Khand reaction
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Perhydro-1,3-benzoxazines derived from (-)-8-amino menthol behave as masked aldehydes and chiral templates in diastereoselective intramolecular Pauson-Khand reactions with norbornene and norbornadiene. The regioselectivity is excellent for unsubstituted o
- Maestro, Alicia,Pedrosa, Rafael,Pérez-Encabo, Alfonso,Pérez-Rueda, Juan J.
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supporting information
p. 9293 - 9300
(2012/11/07)
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- Enhanced Reactivity of Chelating Ortho Esters and Dithio-Ortho Esters Towards Grignard Reagents
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2-Alkoxy-1,3-dithianes, 2-alkoxy-1,3-benzdithioles and bis(2-alkoxy-1,3-dioxolanes) react substantially faster with phenylmagnesium bromide and phenylethynylmagnesium bromide when the 2-alkoxy group can act as a chelating system for magnesium(II).
- Houghton, Roy P.,Dunlop, Jane E.
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p. 2387 - 2400
(2007/10/02)
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