4509-91-5Relevant academic research and scientific papers
Synthesis of chiral branched allylamines through dual photoredox/nickel catalysis
Garbacz, Mateusz,Stecko, Sebastian
supporting information, p. 8578 - 8585 (2021/10/20)
Allylamines are versatile building blocks in the synthesis of various naturally occurring products and pharmaceuticals. In contrast to terminal allylamines, the methods of synthesis of their branched congeners with internal, stereodefined double bonds are less explored. This work describes a new approach for the preparation of allylaminesviacross-coupling of alkyl bromides with simple 3-bromoallylamines by merging the photoredox approach and Ni catalysis. The reaction proceeds under mild conditions, under blue light irradiation, and in the presence of an organic dye, 4CzIPN, as a photocatalyst. The scope of suitable reaction partners is broad, including alkyl bromides bearing reactive functionalities (e.g., esters, nitriles, aldehydes, ketones, epoxides) andN-protected allylamines, as well asN-allylated secondary and tertiary amines and heterocycles. The employment of non-racemic starting materials allows for rapid and easy construction of complex multifunctional allylamine derivatives without the loss of enantiomeric purity.
Electrophotochemical Ring-Opening Bromination oftert-Cycloalkanols
Yamamoto, Kosuke,Toguchi, Hiroyuki,Kuriyama, Masami,Watanabe, Shin,Iwasaki, Fumiaki,Onomura, Osamu
, p. 16177 - 16186 (2021/09/13)
An electrophotochemical ring-opening bromination of unstrainedtert-cycloalkanols has been developed. This electrophotochemical method enables the oxidative transformation of cycloalkanols with 5- to 7-membered rings into synthetically useful ω-bromoketones without the use of chemical oxidants or transition-metal catalysts. Alkoxy radical species would be key intermediates in the present transformation, which generate through homolysis of the O-Br bond in hypobromite intermediates under visible light irradiation.
In-situ-generation of alkylsilyl peroxides from alkyl hydroperoxides and their subsequent copper-catalyzed functionalization with organosilicon compounds
Xu, Weiping,Zhong, Wenfeng,Yang, Qin,Kato, Terumasa,Liu, Yan,Maruoka, Keiji
supporting information, (2021/06/16)
Alkylsilyl peroxides were generated in situ from the corresponding alkyl hydroperoxides using organosilicon compounds of the type Me3SiX (X = CN, N3, and halogens) and an amine base. Subsequent in situ copper-catalyzed homolytic cleavage of the alkylsilyl peroxides afforded alkyl radicals, which were then trapped with X (X = CN, N3, and halogens) to furnish products with new carbon-carbon, carbon-nitrogen, or carbon-halogen bonds in good to high yields.
Far-end halogenated alkyl ketone taking HX as halogen source and synthesis method of far-end halogenated alkyl ketone
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Paragraph 0032; 0061-0068, (2021/08/21)
The invention relates to a far-end halogenated alkyl ketone taking HX as a halogen source and a synthesis method of the far-end halogenated alkyl ketone. The method comprises the following steps that: cycloalkyl peroxy alcohol and a copper acetate catalyst are added in a nitrogen atmosphere, then HCl, HBr and an HI solution are added as halogens, and stirring is carried out at normal temperature; after a reaction is finished, sufficient water is added to extract a reaction solvent N-methyl pyrrolidone, performing washing with saturated saline solution, an organic phase is dried with anhydrous sodium sulfate, the organic phase is concentrated under reduced pressure, so that the solvent can be removed; and column chromatography is performed on the organic phase to obtain a target product. According to the far-end halogenated alkyl ketone taking the HX as the halogen source and the synthesis method of the far-end halogenated alkyl ketoneinvention, industrial bulk raw materials HCl, HBr and an HI solution are used as the halogen source, free radical halogenation of C-C bond cracking is realized, and the far-end halogenated alkyl alkyl ketone compound is obtained with high yield; the byproduct of the reaction is water, so that the environmental pollution is reduced, and the industrial production benefit is greatly improved.
Copper-catalyzed radical ring-opening halogenation with HX
Bai, Ming,Duan, Xin-Hua,Guo, Li-Na,Liu, Shuai,Sun, Qing-Xin,Xu, Peng-Fei
supporting information, p. 8652 - 8655 (2021/09/04)
An efficient copper-catalyzed radical ring-opening halogenation with HX (aq) is described. This protocol features redox-neutral conditions, green halogen sources, and a broad substrate scope, providing practical access to distally chlorinated, brominated and iodinated alkyl ketones and alkyl nitriles with moderate to good yields. This journal is
Decarboxylative Bromination of Sterically Hindered Carboxylic Acids with Hypervalent Iodine(III) Reagents
Kanazawa, Junichiro,Koyamada, Kenta,Miyamoto, Kazunori,Uchiyama, Masanobu,Watanabe, Ayumi
supporting information, p. 1328 - 1334 (2020/08/14)
Sterically hindered three-dimensional (3D) alkyl halides are promising precursors for various reactions; however, they are difficult to synthesize via conventional reactions. We present an efficient and practical method for decarboxylative bromination of sterically hindered 3D aliphatic carboxylic acids using commercially available (diacetoxyiodo)benzene and potassium bromide, one of the most stable and cheapest bromine sources in nature. The present method features a metal-free/Br2-free system, mild reaction conditions, one-pot operation under air at room temperature, wide functional group compatibility, and gram-scale synthetic capability. This highly efficient reaction cleanly converts a broad range of carboxylic acids, the most inexpensive and readily available sources of highly strained/naturally occurring/drug-related scaffolds, into the corresponding alkyl bromides in good to high yields.
Intramolecular Cyclization of Brominated Oxime Ether Promoted with Ytterbium(0) to the Synthesis of Cyclic Imines
Wang, Yiqiong,Huang, Fei,Zhang, Songlin
, p. 5178 - 5181 (2020/08/13)
The first utility of ytterbium(0) as a mediating-metal in the intramolecular cyclization of brominated oxime ether was reported in this paper. In contrast to the prior methods, the N–O bond was used as a receptor of nucleophilic reagent, rather than as a source of N-centered radicals. Cyclic imines were obtained in this one-pot reaction with a broad scope of substrates and feasible reaction conditions.
Ring-opening iodination and bromination of unstrained cycloalkanols through ?-scission of alkoxy radicals
Shi, Jiang-Ling,Wang, Yuankai,Wang, Zixuan,Dou, Bowen,Wang, Jianbo
supporting information, p. 5002 - 5005 (2020/05/18)
Ring-opening iodination or bromination of unstrained cycloalkanols with NaI or NaBr and PhI(OAc)2 under visible light irradiation is developed. In this protocol the concentration of I2is modulated through the generation of triiodide (I3-), thus significantly avoiding undesired side reactions. The reaction is under mild conditions and has a wide substrate scope, thus providing a practically useful method for accessing ω-iodo or ω-bromoketones.
Iminyl Radicals by Reductive Cleavage of N-O Bond in Oxime Ether Promoted by SmI2: A Straightforward Synthesis of Five-Membered Cyclic Imines
Huang, Fei,Zhang, Songlin
, p. 7430 - 7434 (2019/10/11)
A new generation method of N-centered radicals from the reductive cleavage of the N-O bond in oxime ether promoted by SmI2 is reported for the first time. The in-situ-generated N-centered radicals underwent intramolecular cyclization to afford five-membered cyclic imines in two manners: N-centered radical addition and N-centered anion nucleophilic substitution. From a synthetic point of view, an efficient synthetic method of five-membered cyclic imines was developed. A mechanism of the transformation was proposed.
Diazepane Carboxylates as Organocatalysts in the Diels–Alder Reaction of α-Substituted Enals
H?ggman, Nicklas O.,Zank, Benjamin,Jun, HyunJune,Kaldre, Dainis,Gleason, James L.
supporting information, p. 5412 - 5416 (2018/10/20)
Ethyl diazepane carboxylate efficiently catalyzes the Diels–Alder cycloaddition of α-substituted-α,β-unsaturated aldehydes via iminium ion organocatalysis. The reaction is applicable to a range of dienes and dienophiles and generally proceeds at room temperature in the presence of 5 mol-% catalyst and 2.5 mol-% triflic acid co-catalyst. The incorporation of a stereogenic center on the diazepane backbone in combination with a menthyl carbamate produces a catalyst which affords enantioselectivities of 70–95 % ee for the cycloaddition of cyclopentadiene with a range of dienophiles. The enantioselectivity is rationalized via a transition state in which electrostatic stabilization by the carboxylate directs the diene to the more hindered face of the dienophile.
