69352-04-1Relevant articles and documents
Iron-Catalyzed Enantioselective Radical Carboazidation and Diazidation of α,β-Unsaturated Carbonyl Compounds
Liu, Wen,Pu, Maoping,He, Jun,Zhang, Tinghui,Dong, Shunxi,Liu, Xiaohua,Wu, Yun-Dong,Feng, Xiaoming
, p. 11856 - 11863 (2021/08/16)
Azidation of alkenes is an efficient protocol to synthesize organic azides which are important structural motifs in organic synthesis. Enantioselective radical azidation, as a useful strategy to install a C-N3 bond, remains challenging due to the inherently instability and unique structure of radicals. Here, we disclose an efficient enantioselective radical carboazidation and diazidation of α,β-unsaturated ketones and amides catalyzed by chiral N,N′-dioxide/Fe(OTf)2 complexes. An array of substituted alkenes was transformed to the corresponding α-azido carbonyl derivatives in good to excellent enantioselectivities, benefiting the preparation of chiral α-amino ketones, vicinal amino alcohols, and vicinal diamines. Control experiments and mechanistic studies proved the radical pathway in the reaction process. The DFT calculations showed that the azido transferred to the radical intermediate via an intramolecular five-membered transition state with the internal nitrogen of the Fe-N3 species.
One-Pot Synthesis of Primary and Secondary Aliphatic Amines via Mild and Selective sp3 C?H Imination
Comito, Robert J.,Ghosh, Subrata K.,Hu, Mengnan
, p. 17601 - 17608 (2021/11/03)
The direct replacement of sp3 C?H bonds with simple amine units (?NH2) remains synthetically challenging, although primary aliphatic amines are ubiquitous in medicinal chemistry and natural product synthesis. We report a mild and selective protocol for preparing primary and secondary aliphatic amines in a single pot, based on intermolecular sp3 C?H imination. The first C?H imination of diverse alkanes, this method shows useful site-selectivity within substrates bearing multiple sp3 C?H bonds. Furthermore, this reaction tolerates polar functional groups relevant for complex molecule synthesis, highlighted in the synthesis of amine pharmaceuticals and amination of natural products. We characterize a unique C?H imination mechanism based on radical rebound to an iminyl radical, supported by kinetic isotope effects, stereoablation, resubmission, and computational modeling. This work constitutes a selective method for complex amine synthesis and a new mechanistic platform for C?H amination.
Oxidative cyanation of 2-oxindoles: formal total synthesis of (±)-gliocladin C
Bisai, Alakesh,Das, Mrinal Kanti,De, Subhadip,Maity, Arindam,Naskar, Malay,Roy, Avishek
supporting information, 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.
Metal-Free Oxidative Cross Coupling of Indoles with Electron-Rich (Hetero)arenes
Caramenti, Paola,Nandi, Raj Kumar,Waser, Jerome
supporting information, p. 10049 - 10053 (2018/07/29)
A new method for the synthesis of bi-heteroaryls is reported, based on the umpolung of indoles with benziodoxol(on)e hypervalent iodine reagents (IndoleBX). The oxidative coupling of IndoleBX with an equimolar amount of electron-rich benzenes, indoles, pyrroles, and thiophenes proceeded under mild transition-metal-free conditions. Functionalized non-symmetrical bi-indolyl heterocycles were accessed efficiently. Introduction of a new type of C2-substituted indole benziodoxole reagents further allowed extending the scope of the reaction to NH unprotected and C3-alkylated indoles. The obtained bi-heterocycles are important building blocks in synthetic and medicinal chemistry, and could be easily transformed into more complex heterocyclic systems.
Radical C?H-Amination of Heteroarenes using Dual Initiation by Visible Light and Iodine
Lucchetti, Nicola,Tkacheva, Anastasia,Fantasia, Serena,Mu?iz, Kilian
, p. 3889 - 3893 (2018/09/21)
A novel light-induced C?H amination of heteroarenes can be accomplished with preformed iodine(III) reagents as the combined oxidant and nitrogen source. The reaction requires the use of a small amount of molecular iodine, which under photochemical activation generates in situ an iodine(I) reagent as the initiator of the radical amination reaction. A total of 32 examples exemplify the broad scope of the transformation. (Figure presented.).
Determining the predominant tautomeric structure of iodine-based group-transfer reagents by 17O NMR spectroscopy
Santschi, Nico,Pitts, Cody Ross,Jelier, Benson J.,Verel, René
, p. 2289 - 2294 (2018/09/14)
Cyclic benziodoxole systems have become a premier scaffold for the design of electrophilic transfer reagents. A particularly intriguing aspect is the fundamental II–IIII tautomerism about the hypervalent bond, which has led in certain cases to a surprising re-evaluation of the classic hypervalent structure. Thus, through a combination of 17O NMR spectroscopy at natural abundance with DFT calculations, we establish a convenient method to provide solution-phase structural insights for this class of ubiquitous reagents. In particular, we confirm that Shen’s revised, electrophilic SCF3-transfer reagent also adopts an "acyclic" thioperoxide tautomeric form in solution. After calibration, the approach described herein likely provides a more general and direct method to distinguish between cyclic and acyclic structural features based on a single experimental 17O NMR spectrum and a computationally-derived isotropic shift value. Furthermore, we apply this structural elucidation technique to predict the constitution of an electrophilic iodine-based cyano-transfer reagent as an NC–I–O motif and study the acid-mediated activation of Togni's trifluoromethylation reagent.
Divergent Access to (1,1) and (1,2)-Azidolactones from Alkenes using Hypervalent Iodine Reagents
Alazet, Sébastien,Le Vaillant, Franck,Nicolai, Stefano,Courant, Thibaut,Waser, Jerome
, p. 9501 - 9504 (2017/07/22)
A versatile synthesis of azidolactones through azidation and cyclization of carboxylic acids onto alkenes has been developed. Based on either photoredox or palladium catalysis, (1,1) and (1,2) azido lactones can be selectively synthesized. The choice of catalyst and benziodoxol(on)e reagent serving as azide source was essential to initiate either a radical or Lewis acid mediated process with divergent outcome. These transformations were carried out under mild conditions using a low catalyst loading and gave access to a large scope of azido lactones.
Synthesis and Structure of Hypervalent Iodine(III) Reagents Containing Phthalimidate and Application to Oxidative Amination Reactions
Kiyokawa, Kensuke,Kosaka, Tomoki,Kojima, Takumi,Minakata, Satoshi
, p. 13719 - 13723 (2015/11/11)
A new class of hypervalent iodine reagents containing phthalimidate was synthesized, and structurally characterized by X-ray analysis. The benziodoxole-based reagent displays satisfactory solubility in common organic solvents and is reasonably stable in solution as well as in the solid state. The reagent was used for the oxidative amination of the C(sp3)-H bond of N,N-dimethylanilines. In addition, the reagent was also applicable to oxidative amination with rearrangement of trialkylamines as well as enamines that were prepared in situ from secondary amines and aldehydes.
Enantioselective Synthesis of Homoallylic Azides and Nitriles via Palladium-Catalyzed Decarboxylative Allylation
Vita, Maria Victoria,Caramenti, Paola,Waser, Jerome
supporting information, p. 5832 - 5835 (2015/12/11)
Azides and nitriles are important building blocks for the synthesis of nitrogen-containing bioactive compounds. The first example of enantioselective palladium-catalyzed decarboxylative allylation of α-azido and cyano β-ketoesters is reported. Indanone derivatives were obtained in 50-88% yield/77-97% ee and 46-98% yield/78-93% ee for azide and nitrile substituents, respectively. The required starting materials were synthesized in one step from ketoesters via electrophilic azidation and cyanation using benziodoxole hypervalent iodine reagents. The products could be easily converted into useful nitrogen-containing building blocks, such as triazoles, amides, or α- and β- amino ketones.
One-pot synthesis of hypervalent iodine reagents for electrophilic trifluoromethylation
Matousek, Vaclav,Pietrasiak, Ewa,Schwenk, Rino,Togni, Antonio
, p. 6763 - 6768 (2013/07/26)
Simplified syntheses suited for large scale preparations of the two hypervalent iodine reagents 1 and 2 for electrophilic trifluoromethylation are reported. In both cases, the stoichiometric oxidants sodium metaperiodate and tert-butyl hypochlorite have been replaced by trichloroisocyanuric acid. Reagent 1 is accessible in a one-pot procedure from 2-iodobenzoic acid in 72% yield. Reagent 2 was prepared via fluoroiodane 11 in a considerably shorter reaction time and with no need of an accurate temperature control.
