242484-65-7Relevant articles and documents
p-Toluenesulfonic acid catalysed fluorination of α-branched ketones for the construction of fluorinated quaternary carbon centres
Tang, Shi-Zhong,Bian, Hong-Li,Zhan, Zong-Song,Chen, Meng-En,Lv, Jian-Wei,Xie, Shaolei,Zhang, Fu-Min
supporting information, p. 12377 - 12380 (2018/11/30)
A p-toluenesulfonic acid catalyzed fluorination of α-branched ketones for the construction of fluorinated quaternary carbon centers has been developed, featuring a broad substrate scope, environmentally benign reaction conditions, and operational simplicity.
Catalyst-Free Decarboxylative Fluorination of Tertiary β-Keto Carboxylic Acids
Katada, Misaki,Kitahara, Kazumasa,Iwasa, Seiji,Shibatomi, Kazutaka
supporting information, p. 2408 - 2411 (2018/11/23)
Decarboxylative fluorination of tertiary β-keto carboxylic acids was performed using an electrophilic fluorinating reagent. The reaction proceeded in the absence of a catalyst or base to yield the corresponding α-fluoroketones with tertiary fluorocarbons in good to high yields. Considering that the α-fluorination of asymmetrical ketones often causes problems with the regioselectivity between the α- and α′-positions, this method could be a good alternative to the α-fluorination of simple ketones for the synthesis of tertiary fluoroketones.
Asymmetric fluorination of enamides: Access to α-fluoroimines using an anionic chiral phase-transfer catalyst
Phipps, Robert J.,Hiramatsu, Kenichi,Toste, F. Dean
, p. 8376 - 8379 (2012/06/30)
The use of a BINOL-derived phosphate as a chiral anionic phase-transfer catalyst in a nonpolar solvent allows the enantioselective fluorination of enamides using Selectfluor as the fluorinating reagent. We demonstrate that a wide range of stable and synthetically versatile α-(fluoro)benzoylimines can be readily accessed with high enantioselectivity. These compounds have the potential to be readily elaborated into a range of highly stereodefined β-fluoroamines, compounds that constitute highly valuable building blocks of particular importance in the synthesis of pharmaceuticals.
N-Fluoro-(3,5-di-tert-butyl-4-methoxy)benzenesulfonimide (NFBSI): A sterically demanding electrophilic fluorinating reagent for enantioselective fluorination
Yasui, Hiroyuki,Yamamoto, Takeshi,Ishimaru, Takehisa,Fukuzumi, Takeo,Tokunaga, Etsuko,Akikazu, Kakehi,Shiro, Motoo,Shibata, Norio
experimental part, p. 222 - 225 (2011/04/26)
We disclose here a novel electrophilic fluorinating reagent, N-fluoro-(3,5-di-tert-butyl-4-methoxy)benzenesulfonimide (NFBSI) as a sterically demanding analogue of popular fluorinating reagent, N-fluorobenzenesulfonmide (NFSI). NFBSI improves the enantios
Intramolecular palladium-catalyzed alkane C-H arylation from aryl chlorides
Rousseaux, Sophie,Davi, Michael,Sofack-Kreutzer, Julien,Pierre, Cathleen,Kefalidis, Christos E.,Clot, Eric,Fagnou, Keith,Baudoin, Olivier
supporting information; experimental part, p. 10706 - 10716 (2010/09/17)
The first examples of efficient and general palladium-catalyzed intramolecular C(sp3)-H arylation of (hetero)aryl chlorides, giving rise to a variety of valuable cyclobutarenes, indanes, indolines, dihydrobenzofurans, and indanones, are described. The use of aryl and heteroaryl chlorides significantly improves the scope of C(sp3)-H arylation by facilitating the preparation of reaction substrates. Careful optimization studies have shown that the palladium ligand and the base/solvent combination are crucial to obtaining the desired class of product in high yields. Overall, three sets of reaction conditions employing PtBu3, PCyp3, or PCy3 as the palladium ligand and K 2CO3/DMF or Cs2CO3/pivalic acid/mesitylene as the base/solvent combination allowed five different classes of products to be accessed using this methodology. In total, more than 40 examples of C-H arylation have been performed successfully. When several types of C(sp3)-H bond were present in the substrate, the arylation was found to occur regioselectively at primary C-H bonds vs secondary or tertiary positions. In addition, in the presence of several primary C-H bonds, selectivity trends correlate with the size of the palladacyclic intermediate, with five-membered rings being favored over six- and seven-membered rings. Regio- and diastereoselectivity issues were studied computationally in the prototypal case of indane formation. DFT(B3PW91) calculations demonstrated that C-H activation is the rate-determining step and that the creation of a C-H agostic interaction, increasing the acidity of a geminal C-H bond, is a critical factor for the regiochemistry control.
Enantioselective electrophilic fluorinations: A study of the fluorine-transfer from achiral N-F reagents to cinchona alkaloids
Baudequin, Christine,Loubassou, Jean-Fran?ois,Plaquevent, Jean-Christophe,Cahard, Dominique
, p. 189 - 193 (2007/10/03)
A transfer fluorination on cinchona alkaloids with the aid of achiral N-F fluorine-transfer reagents is described. Ten commercially available reagents were evaluated. Selectfluors 9 and 10, Accufluor 11,N-fluorobenzenesulfonimide (NFSi) 13, and N-fluoro-2,6-dichloropyridinium tetrafluoroborate 17 are effective fluorine-transfer reagents. The N-fluoroammonium salts of cinchona alkaloids thus prepared were employed in the construction of stereogenic fluorinated carbon centers with enantioselectivity as high as 85%. We also demonstrated that ionic liquids are effective green solvents for the development of this methodology.
An efficient enantioselective fluorination of various β-ketoesters catalyzed by chiral palladium complexes
Hamashima, Yoshitaka,Yagi, Kenji,Takano, Hisashi,Tamas, Laszlo,Sodeoka, Mikiko
, p. 14530 - 14531 (2007/10/03)
Reflecting the importance of fluorinated organic compounds in medicinal chemistry, development of an efficient method for catalytic enantioselective fluorination is increasingly desirable. Using a novel palladium complex 2 (1-2.5 mol %), various β-ketoest
N-Fluoro-3-ethyl-3-methyl-1,1-dioxo-2,3-dihydro-1H-1λ 6-benzo[e]1,2-thiazin-4-one, a new and efficient agent for electrophilic fluorination of carbanions
Takeuchi, Yoshio,Liu, Zhaopeng,Suzuki, Emiko,Shibata, Norio,Kirk, Kenneth L.
, p. 65 - 67 (2007/10/03)
N-Fluoro-3-ethyl-3-methyl-1,1-dioxo-2,3-dihydro-1H-1λ 6-benzo[e]1,2-thiazin-4-one (1) was prepared in good yield by fluorination of the corresponding sultam (3) with FClO3. The sultam (3) was prepared from saccharin (2) in 3 steps. T
Expeditious synthesis of 3,4-dihydro-2H-1λ6-benzo[e] [1,2]thiazine 1,1-dioxides
Takeuchi, Yoshio,Liu, Zhaopeng,Satoh, Akira,Shiragami, Tomoki,Shibata, Norio
, p. 1730 - 1733 (2007/10/03)
A novel pathway for the preparation of 3,4-dihydro-2H-1λ6- benzo[e][1,2lthiazine 1,1-dioxides 3 via an orthomethyl lithiation/cyclization reaction of N-acyl-o-toluenesulfonamides 5 is reported. Readily available N-acyl-o-toluenesulfonamides 5 were treated with 2 eq of n-BuLi at -78°C - 0δC to give the corresponding sultams 6 in moderate to good yields. The resulting sultams 6 were converted to saturated sultams 3, which can be considered as one carbon-extended homologues of the Oppolzer suitams 1, in high yields by hydrogenation. Studies on the scope and limitation of this annulation for the preparation of sultams are discussed. Demonstration of the feasibility of using the sultams 3 templates for an electorophilic fluorinating agent is also described.
