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
supporting information, 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.
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.
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.