1829-26-1Relevant articles and documents
Site Selective Chlorination of C(sp3)?H Bonds Suitable for Late-Stage Functionalization
Fawcett, Alexander,Keller, M. Josephine,Herrera, Zachary,Hartwig, John F.
, p. 8276 - 8283 (2021/03/15)
C(sp3)?Cl bonds are present in numerous biologically active small molecules, and an ideal route for their preparation is by the chlorination of a C(sp3)?H bond. However, most current methods for the chlorination of C(sp3)?H bonds are insufficiently site selective and tolerant of functional groups to be applicable to the late-stage functionalization of complex molecules. We report a method for the highly selective chlorination of tertiary and benzylic C(sp3)?H bonds to produce the corresponding chlorides, generally in high yields. The reaction occurs with a mixture of an azidoiodinane, which generates a selective H-atom abstractor under mild conditions, and a readily-accessible and inexpensive copper(II) chloride complex, which efficiently transfers a chlorine atom. The reaction's exceptional functional group tolerance is demonstrated by the chlorination of >30 diversely functionalized substrates and the late-stage chlorination of a dozen derivatives of natural products and active pharmaceutical ingredients.
Practical synthesis of 2-iodosobenzoic acid (IBA) without contamination by hazardous 2-iodoxybenzoic acid (IBX) under mild conditions
China, Hideyasu,Dohi, Toshifumi,Kageyama, Nami,Takenaga, Naoko,Yatabe, Hotaka
, (2021/06/18)
We report a convenient and practical method for the preparation of nonexplosive cyclic hypervalent iodine(III) oxidants as efficient organocatalysts and reagents for various reactions using Oxone in aqueous solution under mild conditions at room temperature. The thus obtained 2-iodosobenzoic acids (IBAs) could be used as precursors of other cyclic organoiodine(III) derivatives by the solvolytic derivatization of the hydroxy group under mild conditions of 80 °C or lower temperature. These sequential procedures are highly reliable to selectively afford cyclic hypervalent iodine compounds in excellent yields without contamination by hazardous pentavalent iodine(III) compound.
N-Cyanation of Primary and Secondary Amines with Cyanobenzio-doxolone (CBX) Reagent
Chen, Zimin,Yuan, Weiming
, p. 14836 - 14840 (2021/09/30)
An efficient electrophilic N-cyanation of amines with a stable and less-toxic cyanobenziodoxole reagent towards the synthesis of cyanamides is disclosed. This synthetically practicable strategy allows the construction of a wide variety of cyanamides under very mild and simple conditions with a broad functional group compatibility, and showcases a huge potential in late-stage modification of complex molecules.
Direct Photoexcitation of Ethynylbenziodoxolones: An Alternative to Photocatalysis for Alkynylation Reactions**
Amos, Stephanie G. E.,Cavalli, Diana,Le Vaillant, Franck,Waser, Jerome
, 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.
Tosyloxybenziodoxolone: A Platform for Performing the Umpolung of Alkynes in One-Pot Transformations
Borrel, Julien,Waser, Jerome
, (2021/12/27)
Ethynylbenziodoxolones (EBXs) are commonly encountered reagents for the electrophilic alkynylation of nucleophiles. Herein, we report a one-pot, two-step process for EBX generation and their direct application in substrate functionalization. Our approach enables us to bypass the originally mandatory isolation and purification of the reagents, resulting in a more efficient synthesis. We could apply this process to seven different transformations involving both two- and one-electron nucleophiles to obtain a large variety of alkynylated products.
Hypervalent Iodine(III)-Promoted Radical Oxidative C-H Annulation of Arylamines with α-Keto Acids
Long, Lipeng,Wang, Jieyan,Gu, Liuqing,Yang, Shiguang,Qiao, Liang,Luo, Guotian,Chen, Zhengwang
, p. 12084 - 12092 (2021/08/24)
A novel catalyst-free radical oxidative C-H annulation reaction of arylamines with α-keto acids toward benzoxazin-2-ones synthesis under mild conditions was developed. This hypervalent iodine(III)-promoted process eliminated the use of a metal catalyst or additive with high levels of functional group tolerance. Hypervalent iodine(III) was both an oxidant and a radical initiator for this reaction. The synthetic utility of this method was confirmed by the synthesis of the natural product cephalandole A.
Synthesis of Diverse Aryliodine(III) Reagents by Anodic Oxidation?
Zu, Bing,Ke, Jie,Guo, Yonghong,He, Chuan
supporting information, p. 627 - 632 (2021/02/12)
An anodic oxidation enabled synthesis of hypervalent iodine(III) reagents from aryl iodides is demonstrated. Under mild electrochemical conditions, a range of aryliodine(III) reagents including iodosylarenes, (difunctionaliodo)arenes, benziodoxoles and diaryliodonium salts can be efficiently synthesized and derivatized in good to excellent yields with high selectivity. As only electrons serve as the oxidation reagents, this method offers a more straightforward and sustainable manner avoiding the use of expensive or hazardous chemical oxidants.
Oxidative cyanation of 2-oxindoles: formal total synthesis of (±)-gliocladin C
Bisai, Alakesh,Das, Mrinal Kanti,De, Subhadip,Maity, Arindam,Naskar, Malay,Roy, Avishek
, p. 1679 - 1684 (2020/03/05)
Efficient oxidative direct cyanations of 3-alkyl/aryl 2-oxindoles using Cyano-1,2-BenziodoXol-3(1H)-one (CBX) (2a) have been reported under 'transition metal-free' conditions to synthesize a wide variety of 3-cyano 3-alkyl/aryl 2-oxindoles sharing an all-carbon quaternary center under additive-free conditions. The application of this process is shown by the formal total synthesis of (±)-gliocladin C (11c) in a few steps.
Copper-catalyzed oxyvinylation of diazo compounds
Pisella, Guillaume,Gagnebin, Alec,Waser, Jerome
, p. 3884 - 3889 (2020/05/14)
A copper(I)-catalyzed vinylation of diazo compounds with vinylbenziodoxolone reagents (VBX) as partners is reported. The transformation tolerates diverse functionalities on both reagents delivering polyfunctionalized vinylated products. The strategy was successfully extended to a three-component/intermolecular version with alcohols. The obtained products contain synthetically versatile functional groups, such as an aryl iodide, an ester, and an allylic leaving group, enabling further modification.
Site-Selective Copper-Catalyzed Azidation of Benzylic C-H Bonds
Suh, Sung-Eun,Chen, Si-Jie,Mandal, Mukunda,Guzei, Ilia A.,Cramer, Christopher J.,Stahl, Shannon S.
, p. 11388 - 11393 (2020/07/21)
Site selectivity represents a key challenge for non-directed C-H functionalization, even when the C-H bond is intrinsically reactive. Here, we report a copper-catalyzed method for benzylic C-H azidation of diverse molecules. Experimental and density functional theory studies suggest the benzyl radical reacts with a CuII-azide species via a radical-polar crossover pathway. Comparison of this method with other C-H azidation methods highlights its unique site selectivity, and conversions of the benzyl azide products into amine, triazole, tetrazole, and pyrrole functional groups highlight the broad utility of this method for target molecule synthesis and medicinal chemistry.