120749-62-4Relevant academic research and scientific papers
Visible Light-Induced Direct S0→ TnTransition of Benzophenone Promotes C(sp3)-H Alkynylation of Ethers and Amides
Matsumoto, Koki,Nakajima, Masaya,Nemoto, Tetsuhiro
, p. 11802 - 11811 (2020)
Benzophenone has an S0 → S1 absorption band at 365 nm. However, the rarely reported S0 → Tn transition occurs upon irradiation at longer wavelengths. Herein, we employed benzophenone as a catalyst and exploited its S0 → Tn transition in C(sp3)-H alkynylations with hypervalent iodine reagents. The selective benzophenone excitation prevented alkynylating reagent decomposition, enabling the reaction to proceed under mild conditions. The reaction mechanism was investigated by spectroscopic and computational studies.
Decatungstate as Direct Hydrogen Atom Transfer Photocatalyst for SOMOphilic Alkynylation
Capaldo, Luca,Ravelli, Davide
, p. 2243 - 2247 (2021/04/05)
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
Copper-Catalyzed Intermolecular Alkynylation and Allylation of Unactivated C(sp3)-H Bonds via Hydrogen Atom Transfer
Liang, Lei,Guo, Ge,Li, Chen,Wang, Song-Lin,Wang, Yue-Hui,Guo, Hai-Ming,Niu, Hong-Ying
, p. 8575 - 8579 (2021/11/13)
We describe Cu-catalyzed intermolecular alkynylation and allylation of unactivated C(sp3)-H bonds with singly occupied molecular orbital-philes (SOMO-philes) via hydrogen atom transfer (HAT). Employing N-fluoro-sulfonamide as a HAT reagent, a set of subst
Direct Photoexcitation of Ethynylbenziodoxolones: An Alternative to Photocatalysis for Alkynylation Reactions**
Amos, Stephanie G. E.,Cavalli, Diana,Le Vaillant, Franck,Waser, Jerome
supporting information, p. 23827 - 23834 (2021/09/25)
Ethynylbenziodoxolones (EBXs) are commonly used as radical traps in photocatalytic alkynylations. Herein, we report that aryl-substituted EBX reagents can be directly activated by visible light irradiation. They act as both oxidants and radical traps, alleviating the need for a photocatalyst in several reported EBX-mediated processes, including decarboxylative and deboronative alkynylations, the oxyalkynylation of enamides and the C?H alkynylation of THF. Furthermore, the method could be applied to the synthesis of alkynylated quaternary centers from tertiary alcohols via stable oxalate salts and from tertiary amines via aryl imines. A photocatalytic process using 4CzIPN as an organic dye was also developed for the deoxyalkynylation of oxalates.
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
supporting information, 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.
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.
, 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.
Phenylglyoxylic Acid: An Efficient Initiator for the Photochemical Hydrogen Atom Transfer C?H Functionalization of Heterocycles
Papadopoulos, Giorgos N.,Kokotou, Maroula G.,Spiliopoulou, Nikoleta,Nikitas, Nikolaos F.,Voutyritsa, Errika,Tzaras, Dimitrios I.,Kaplaneris, Nikolaos,Kokotos, Christoforos G.
, p. 5934 - 5944 (2020/09/09)
C?H functionalization at the α-position of heterocycles has become a rapidly growing area of research. Herein, a cheap and efficient photochemical method was developed for the C?H functionalization of heterocycles. Phenylglyoxylic acid (PhCOCOOH) could behave as an alternative to metal-based catalysts and organic dyes and provided a very general and wide array of photochemical C?H alkylation, alkenylation, and alkynylation, as well as C?N bond forming reaction methodologies. This novel, mild, and metal-free protocol was successfully employed in the functionalization of a wide range of C?H bonds, utilizing not only O- or N-heterocycles, but also the less studied S-heterocycles.
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.
Method for synthesizing alpha-alkynyl substituted ether compounds
-
Paragraph 0025-0027, (2018/04/01)
The invention discloses a method for preparing alpha-alkynyl substituted ether compounds. The method comprises the following steps: taking propiolic acid as a raw material, and synthesizing substituted phenylpropiolic acid under conditions of substituted iodobenzene, 1,8-diazabicyclo[5.4.0]undec-7-ene, (beta-4)-platinu and dimethyl sulfoxide; taking substituted phenylpropiolic acid and p-bromophenol as raw materials, and synthesizing p-bromophenyl substituted phenylpropiolic acid ester under the conditions of 4-dimethylaminopyridine and N,N'-Dicyclohexylcarbodiimide; and performing an alkynylation reaction on the p-bromophenyl substituted phenylpropiolic acid ester in participation of tert-butyl hydroperoxide, cesium carbonate and tetrahydrofuran, and finally synthesizing alpha-alkynyl substituted ether products. According to the method disclosed by the invention, simple and readily available acetylene esters serve as an alkynylation reagent, and the target products, namely alpha-alkynyl substituted ether compounds, are synthesized in a green and environmental-friendly manner under mild conditions. The compounds play an important role in construction of multiple medical intermediates and bio-active structures.
Radical C(sp3)-H alkenylation, alkynylation and allylation of ethers and amides enabled by photocatalysis
Paul, Subhasis,Guin, Joyram
, 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.
