132723-33-2Relevant academic research and scientific papers
Aromatic organozinc reagents as nucleophiles in the α-arylation of piperidine and tetrahydropyran
Le Gall, Erwan,Gosmini, Corinne,Troupel, Michel
, p. 455 - 458 (2006)
The arylation at the α-position of piperidine derivatives is achieved in good yield using aromatic organozinc reagents and either 2-methoxylated or α-cyanated piperidine. Oxygen-containing heterocycles such as 2-methoxy-tetrahydropyran reacts in a same manner to yield efficiently 2-arylated tetrahydropyran.
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.
Heterocyclization involving benzylic C(sp3)-H functionalization enabled by visible light photoredox catalysis
Pandey, Ganesh,Laha, Ramkrishna,Mondal, Pradip Kumar
supporting information, p. 9689 - 9692 (2019/08/15)
A general and efficient method for heterocyclization involving benzylic C(sp3)-H functionalization enabled by visible light photoredox catalysis to access a wide range of structurally diverse oxygen as well as nitrogen heterocycles up to a gram scale is reported. The potential application of this new methodology is demonstrated by the total synthesis of (-)-codonopsinine and (+)-centrolobine. Herein it is proposed that selectfluor, unlike a fluorinating reagent, acts as an oxidative quencher and a hydrogen radical acceptor.
Aryl Boronic Acid Catalysed Dehydrative Substitution of Benzylic Alcohols for C?O Bond Formation
Estopi?á-Durán, Susana,Donnelly, Liam J.,Mclean, Euan B.,Hockin, Bryony M.,Slawin, Alexandra M. Z.,Taylor, James E.
supporting information, p. 3950 - 3956 (2019/02/16)
A combination of pentafluorophenylboronic acid and oxalic acid catalyses the dehydrative substitution of benzylic alcohols with a second alcohol to form new C?O bonds. This method has been applied to the intermolecular substitution of benzylic alcohols to form symmetrical ethers, intramolecular cyclisations of diols to form aryl-substituted tetrahydrofuran and tetrahydropyran derivatives, and intermolecular crossed-etherification reactions between two different alcohols. Mechanistic control experiments have identified a potential catalytic intermediate formed between the aryl boronic acid and oxalic acid.
Visible-Light-Induced Cyclization of Electron-Enriched Phenyl Benzyl Sulfides: Synthesis of Tetrahydrofurans and Tetrahydropyrans
Li, Wei,Yang, Chao,Gao, Guo-Lin,Xia, Wujiong
, p. 1391 - 1396 (2016/06/01)
A new approach to the preparation of tetrahydrofurans and tetrahydropyrans through a photoredox catalytic process is described. The introduction of a phenylsulfanyl auxiliary group permits the substrates to be readily oxidized to form cationic intermediates for sequential intramolecular cyclization. The method features mild reaction conditions and operational simplicity.
New method for C-H arylation/alkylation at α-position of cyclic aliphatic ethers by iron-oxide mediated reaction
Singh, Parvinder Pal,Gudup, Satish,Aruri, Hariprasad,Singh, Umed,Ambala, Srinivas,Yadav, Mahipal,Sawant, Sanghapal D.,Vishwakarma, Ram A.
experimental part, p. 1587 - 1597 (2012/03/22)
We report a new and efficient iron oxide catalyzed cross-coupling reaction between organometallic species such as alkyl/arylmagnesium halides or organolithium species and α-hydrogen bearing cyclic unbranched and branched aliphatic ethers via activation of C(sp3)-H. In the presence of 1 mol% of iron oxide, five and six membered unbranched cyclic ethers such as tetrahydrofuran and tetrahydropyran gave good to excellent yields of cross-coupled products. Whereas, in case of branched ether such as 2-methyltetrahydrofuran, it was observed that the arylation occurred at both the sides and gave moderate yields of a mixture of regioisomers. Among the organometallic species used, alkyl organometallic reagents gave less yields as compared to aryl organometallics.
Gold-catalysed cyclic ether formation from diols
Jiang, Xiaolu,London, Emma K.,Morris, David J.,Clarkson, Guy J.,Wills, Martin
experimental part, p. 9828 - 9834 (2011/02/23)
Gold(I) and (III) salts have been found to be highly effective at the catalysis of ether formation from alcohols. Intramolecular ether formation of a 1,5-diol was also achieved, with a stereoselectivity that indicates that an SN1 mechanism predominates. In an attempt to form a seven-membered ring, a stable 14-membered dimer product was also formed. Attempts to control the diastereoselectivity of the reaction using a chiral anionic counterion did not give products with a high de.
Photochemical arylation of alkenols: Role of intermediates and synthetic significance
Protti, Stefano,Dondi, Daniele,Fagnoni, Maurizio,Albini, Angelo
scheme or table, p. 2240 - 2247 (2009/04/07)
A one-pot, tandem synthesis of cyclic ethers is obtained by addition of photogenerated phenyl cations to hydroxyalkenes. Thus, 2- (or 3-) phenyl-substituted tetrahydrofurans were prepared by irradiation of 4-chloro-N,N-dimethylaniline, -anisole, and -phenol with β-hydroxyalkenes and 2-benzyltetrahydrofurans with λ-hydroxyalkenes. With nonterminal alkenes [diastereomeric (E)- and (Z)-3-hexen-1-ols] trans-2-ethyl-3- aryltetrahydrofuran derivatives were stereoselectively formed from both isomers. The output of the photoreaction is structure and solvent dependent and is rationalized through the intermediacy of a phenonium ion from the addition of the primarily formed triplet phenyl cation to the alkenol double bond. Intramolecular addition of the OH group to form benzyl (aryl) tetrahydrofurans is favored in polar protic solvents, where hydride shifts to form aryltetrahydropyrans also occur, whereas in ethyl acetate, intermolecular addition of the chloride anion to the phenonium ion takes place. The mechanism of the above reactions is also discussed on the basis of computational data. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Controlling factors determining the regiochemistry of intramolecular alkoxymercuration
Senda, Yasuhisa,Kanto, Hiroko,Itoh, Hiroki
, p. 1143 - 1146 (2007/10/03)
The intramolecular alkoxymercuration of (E)-5-arylpent-4-en-1-ols indicated that the regioselectivity is closely related to the Hammett constants of the para-substituents on the benzene ring. Large solvent effects on the regioselectivity were also observe
Polar and steric substituent effects in 5-exo-trig cyclizations of 1-aryl-4-penten-1-oxyl radicals
Hartung, Jens,Hiller, Margit,Schmidt, Philipp
, p. 1425 - 1436 (2007/10/03)
A series of 1-aryl-substituted 4-penten-1-oxyl radicals 2 were generated from parent N-alkoxypyridinethiones 6. The intermediates 2 undergo 5-exo-trig cyclizations which are sensitive to polar and steric substituent effects. Thus, para groups in the aroma
