69352-05-2Relevant articles and documents
Iron-Catalyzed Enantioselective Radical Carboazidation and Diazidation of α,β-Unsaturated Carbonyl Compounds
Dong, Shunxi,Feng, Xiaoming,He, Jun,Liu, Wen,Liu, Xiaohua,Pu, Maoping,Wu, Yun-Dong,Zhang, Tinghui
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.
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
supporting information, 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.
Synthesis, Characterization, and Reactivity of a Hypervalent-Iodine-Based Nitrooxylating Reagent
Calvo, Roxan,Katayev, Dmitry,Le Tellier, Antoine,Nater, Darryl,Nauser, Thomas,Rombach, David
supporting information, p. 17162 - 17168 (2020/07/31)
Herein, the synthesis and characterization of a hypervalent-iodine-based reagent that enables a direct and selective nitrooxylation of enolizable C?H bonds to access a broad array of organic nitrate esters is reported. This compound is bench stable, easy-
Radical C?H-Amination of Heteroarenes using Dual Initiation by Visible Light and Iodine
Lucchetti, Nicola,Tkacheva, Anastasia,Fantasia, Serena,Mu?iz, Kilian
supporting information, 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.).
Synthesis, Characterization, and Reaction of a Both Inter- and Intramolecularly Coordinated Pseudocyclic Iodosylbenzene–Trifluoroacetic Acid Complexes
Yudasaka, Masaharu,Maruyama, Toshifumi,Yamaguchi, Eiji,Tada, Norihiro,Itoh, Akichika
, p. 550 - 556 (2018/02/09)
An ortho-substituted ether-oxygen-coordinated pseudocyclic iodosylbenzene-trifluoroacetic acid (pcISB-TFA) complex was synthesized and characterized by X-ray crystallographic analysis. TFA suppresses the disproportionation by both coordination of the oxygen atom to the iodine(III) center through secondary bonding and by hydrogen bonding to the oxygen anion. This bench-stable reagent is highly soluble in common organic solvents and reacts with various organic substrates under mild reaction conditions to give the corresponding products in good yields.
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
supporting information, 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.
Silver-promoted (radio)fluorination of unsaturated carbamates via a radical process
Yang, Bin,Chansaenpak, Kantapat,Wu, Hongmiao,Zhu, Lin,Wang, Mengzhe,Li, Zibo,Lu, Hongjian
supporting information, p. 3497 - 3500 (2017/03/30)
The intramolecular fluorocyclization of unsaturated carbamates is described here using a hypervalent iodine reagent in the presence of a silver catalyst. Both (hetero)aryl-substituted olefins and acrylamides can be utilized as effective substrates. Preliminary mechanistic investigations suggest that the reaction proceeds via a cyclization/1,2-(hetero)aryl migration/fluorination cascade involving an unusual radical process. Furthermore, starting from no-carrier-added [18F]TBAF, a simple one-pot, two-step cascade method was developed for the generation of 18F-labeled heterocycles with high radiochemical purity.
Synthesis of Multisubstituted Triphenylenes and Phenanthrenes by Cascade Reaction of o-Iodobiphenyls or (Z)-β-Halostyrenes with o-Bromobenzyl Alcohols through Two Sequential C-C Bond Formations Catalyzed by a Palladium Complex
Iwasaki, Masayuki,Araki, Yasuhiro,Iino, Shohei,Nishihara, Yasushi
, p. 9247 - 9263 (2015/09/28)
o-Bromobenzyl alcohol has been developed as a novel annulating reagent, bearing both nucleophilic and electrophilic substituents, for the facile synthesis of polycyclic aromatic hydrocarbons. A palladium/electron-deficient phosphine catalyst efficiently coupled o-iodobiphenyls or (Z)-β-halostyrenes with o-bromobenzyl alcohols to afford triphenylenes and phenanthrenes, respectively. The present cascade reaction proceeded through deacetonative cross-coupling and sequential intramolecular cyclization. An array of experimental data suggest that the reaction mechanism involves the equilibrium of 1,4-palladium migration.
Intramolecular fluorocyclizations of unsaturated carboxylic acids with a stable hypervalent fluoroiodane reagent
Geary, Gemma C.,Hope, Eric G.,Stuart, Alison M.
supporting information, p. 14911 - 14914 (2016/02/05)
A new class of fluorinated lactones was prepared by the intramolecular fluorocyclizations of unsaturated carboxylic acids by using the stable fluoroiodane reagent in combination with AgBF4. This unique reaction incorporates a cyclization, an aryl migration, and a fluorination all in one step. The fluoroiodane reagent, prepared easily from fluoride, can also be used without a metal catalyst to give moderate yields within just 1 hour, thus demonstrating that it is a suitable reagent for developing new 18F-labelled radiotracers for PET imaging. All in one: A new class of lactones containing a tertiary alkyl fluoride was prepared in high yields by using a stable fluoroiodane reagent. This unique reaction incorporates a cyclization, an aryl migration, and a fluorination all in one step.
General and practical formation of thiocyanates from thiols
Frei, Reto,Courant, Thibaut,Wodrich, Matthew D.,Waser, Jerome
supporting information, p. 2662 - 2668 (2015/02/05)
A new method for the cyanation of thiols and disulfides using cyanobenziodoxol(on)e hypervalent iodine reagents is described. Both aliphatic and aromatic thiocyanates can be accessed in good yields in a few minutes at room temperature starting from a broad range of thiols with high chemioselectivity. The complete conversion of disulfides to thiocyanates was also possible. Preliminary computational studies indicated a low energy concerted transition state for the cyanation of the thiolate anion or radical. The developed thiocyanate synthesis has broad potential for various applications in synthetic chemistry, chemical biology and materials science.
