70141-82-1Relevant academic research and scientific papers
Photochemical Functionalization of Heterocycles with EBX Reagents: C?H Alkynylation versus Deconstructive Ring Cleavage**
Voutyritsa, Errika,Garreau, Marion,Kokotou, Maroula G.,Triandafillidi, Ierasia,Waser, Jér?me,Kokotos, Christoforos G.
supporting information, p. 14453 - 14460 (2020/10/12)
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.
Site- And enantiodifferentiating C(sp3)-H oxidation enables asymmetric access to structurally and stereochemically diverse saturated cyclic ethers
Liu, Lei,Sun, Shutao,Yang, Yiying,Zhang, Dongju,Zhao, Ran
, p. 19346 - 19353 (2020/12/01)
A manganese-catalyzed site- and enantiodifferentiating oxidation of C(sp3)-H bonds in saturated cyclic ethers has been described. The mild and practical method is applicable to a range of tetrahydrofurans, tetrahydropyrans, and medium-sized cyclic ethers with multiple stereocenters and diverse substituent patterns in high efficiency with extremely efficient site- and enantiodiscrimination. Late-stage application in complex biological active molecules was further demonstrated. Mechanistic studies by combined experiments and computations elucidated the reaction mechanism and origins of stereoselectivity. The ability to employ ether substrates as the limiting reagent, together with a broad substrate scope, and a high level of chiral recognition, represent a valuable demonstration of the utility of asymmetric C(sp3)-H oxidation in complex molecule synthesis.
Graphitic Carbon Nitride Polymer as a Recyclable Photoredox Catalyst for Decarboxylative Alkynylation of Carboxylic Acids
Guo, Jiaqi,Wang, Yating,Li, Yuhang,Lu, Kailin,Liu, Shihui,Wang, Wei,Zhang, Yongqiang
supporting information, p. 3898 - 3904 (2020/08/07)
Visible-light-induced heterogeneous photocatalysis for decarboxylative alkynylation has been performed. The using of cheap, metal-free and recyclable graphitic carbon nitride (g-C3N4) as the photoredox catalyst in the process enables
Visible-Light-Induced Alkynylation of α-C–H Bonds of Ethers with Alkynyl Bromides without External Photocatalyst
Xie, Xiaofei,Liu, Jie,Wang, Lei,Wang, Min
, p. 1534 - 1538 (2019/09/06)
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.
Synthesis of propargylic ethers by gold-mediated reaction of terminal alkynes with acetals
Furuta, Miyu,Sugiyama, Kyoko,Yamaguchi, Minami,Ueda, Hirofumi,Tokuyama, Hidetoshi
, p. 872 - 876 (2019/08/20)
A gold-catalyzed introduction of various terminal alkynes to acetals was investigated. Extensive optimization of the reaction conditions revealed that thermally stable cationic gold catalysts bearing bulky ligands such as 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene 3-1H-benzo[d][1,2,3]triazolyl gold trifluoromethanesulfonate (IPrAu(BTZ-H)OTf) were particularly suitable for the reaction. Additionally, significant solvent effects were observed. Ether solvents such as tetrahydrofuran (THF), cyclo pentyl methyl ether (CPME), and 1,4-dioxane were effective for the reaction. Studies on the scope of substrates and alkynes indicated that various alkynes and acetals were feasible to provide a wide range of propargylic ethers.
Radical C(sp3)-H alkenylation, alkynylation and allylation of ethers and amides enabled by photocatalysis
Paul, Subhasis,Guin, Joyram
supporting information, p. 2530 - 2534 (2017/07/17)
An efficient radical addition/elimination reaction that enables selective incorporation of alkenyl, alkynyl and allyl functional groups into the C(sp3)-H bond under green reaction conditions is developed. The process is based on the catalytic formation of α-alkoxyl/α-amidyl radicals via the homolytic activation of the C(sp3)-H bond of ethers/amides with a catalytic amount of diarylketone in the presence of a household fluorescent light bulb. This simple reaction protocol features good functional group tolerance, scalability, convenient reagents and operating systems. Synthetic application of the method has been demonstrated via the preparation of natural products and different valuable synthones.
Gold-Catalyzed Vinyl Ether Hydroalkynylation: An Alternative Pathway for the Gold-Catalyzed Intermolecular Reaction of Alkenes and Alkynes
Hosseyni, Seyedmorteza,Smith, Courtney A.,Shi, Xiaodong
supporting information, p. 6336 - 6339 (2016/12/23)
In this report, the gold-catalyzed intermolecular reaction of vinyl ethers and terminal alkynes is investigated. Utilizing a triazole gold catalyst lessens gold decomposition in the presence of the vinyl ether and affords an alkynylation product instead of the [2 + 2] product. This protocol has been expanded to include glycal substrates, which undergo a one-pot alkynylation-Ferrier reaction to produce functionalized sugars in moderate to excellent yields with high diastereoselectivity.
Gold(I)/(III)-catalyzed synthesis of cyclic ethers; Valency-controlled cyclization modes
Morita, Nobuyoshi,Yasuda, Arisa,Shibata, Motohiro,Ban, Shintaro,Hashimoto, Yoshimitsu,Okamoto, Iwao,Tamura, Osamu
supporting information, p. 2668 - 2671 (2015/06/16)
Strategic use of oxophilic (hard) gold(III) and π-philic (soft) gold(I) catalysts provides access to two types of cyclic ethers from propargylic alcohols. Thus, heating propargylic alcohols with an oxophilic gold(III) catalyst (AuBr3) results i
Metal-free alkynylation of α-C-H bonds of ethers with ethynylbenziodoxolones
Zhang, Ruo-Yi,Xi, Long-Yi,Zhang, Lei,Liang, Shuai,Chen, Shan-Yong,Yu, Xiao-Qi
, p. 54349 - 54353 (2015/02/02)
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
Practical and highly selective C-H functionalization of structurally diverse ethers
Wan, Miao,Meng, Zhilin,Lou, Hongxiang,Liu, Lei
supporting information, p. 13845 - 13849 (2015/01/16)
A trityl ion mediated C-H functionalization of ethers with a wide range of nucleophiles at ambient temperature has been developed. The reaction displays high chemo-selectivity and good functional group tolerance. The protocol also exhibits excellent regio- and diastereoselectivities for the unsymmetric ethers, thus stereoselectively generating highly functionalized disubstituted 2,5-trans tetrahydrofurans (THF), 2,6-trans tetrahydropyrans (THP), 2,6-trans dihydropyrans (DHP), and 1,3-trans isochromans, and highlighting the capacity of the protocol in complex molecule synthesis.
