38636-02-1Relevant academic research and scientific papers
Catalytic asymmetric diaziridination
Lykke, Lennart,Halskov, Kim Soholm,Carlsen, Bjorn Dreio,Chen, Victor X.,Jorgensen, Karl Anker
, p. 4692 - 4695 (2013)
The first catalytic enantio- and diastereoselective synthesis of diaziridines is presented. Aziridination of N-tosyl aldimines applying modified hydroxylamine under asymmetric phase-transfer catalysis furnished optically active diaziridines. The diaziridines are formed as a single diastereomer in up to 96% ee, containing two orthogonal N-protecting groups, which can be deprotected selectively.
Nucleophilic Addition to Nitrones Using a Flow Microreactor
Arakawa, Yukihiro,Imada, Yasushi,Minagawa, Keiji,Okamoto, Takuma,Ueta, Shun
supporting information, p. 866 - 870 (2020/05/28)
Nucleophilic addition reactions of soft carbon nucleophiles to nitrones in a flow microreactor are reported for the first time. Under microflow conditions at 30 to 0 °C, a range of nitrones can be efficiently transformed into the corresponding oxyiminium ions by reaction with either acyl halides or trialkylsilyl triflates. These can subsequently undergo the addition of nucleophiles including allyltributylstannane, ketene methyl tert-butyldimethylsilyl acetal, and N-silyl ketene imines to afford the corresponding adducts in high yields; such reactions at a similar temperature under batch conditions resulted in lower yields because of undesired side reactions.
Direct N-O bond formation via oxidation of amines with benzoyl peroxide
Banerjee, Amit,Yamamoto, Hisashi
, p. 2124 - 2129 (2019/02/20)
Herein, we report a general and efficient method for direct N-O bond formation without undesirable C-N bond (amide) formation starting from commercially available amines and benzoyl peroxide. The oxidation of 1,2-diamines to furnish bis-(benzoyloxy)-1,2-diamines is reported for the first time. We found that a significant amount of water (BPO?:?water = 3?:?1) in combination with Cs2CO3 is necessary to achieve high selectivity and yield. The reaction conditions are applicable to a wide range of 1,2-diamine and 1,2-disubstituted-1,2-diamine substrates. Additionally this method is highly applicable to primary and secondary amines. Further, the present method can access chiral bis-hydroxamic acids and bis-hydroxyl amines in just two steps from 1,2-diamines. The reaction conditions are simple, mild and inert atmosphere free. The synthetic potential of this methodology is further demonstrated in the short synthesis of a chiral BHA ligand.
Design of modified amine transfer reagents allows the synthesis of α-chiral secondary amines via CuH-catalyzed hydroamination
Niu, Dawen,Buchwald, Stephen L.
, p. 9716 - 9721 (2015/08/18)
The CuH-catalyzed hydroamination of alkenes and alkynes using a silane and an amine transfer reagent represents a simple strategy to access chiral amine products. We have recently reported methods to prepare chiral amines with high efficiency and stereoselectivity using this approach. However, the current technology is limited to the synthesis of trialkylamines from dialkylamine transfer reagents (R2NOBz). When monoalkylamine transfer reagents [RN(H)OBz] were used for the synthesis of chiral secondary amines, competitive, nonproductive consumption of these reagents by the CuH species resulted in poor yields. In this paper, we report the design of a modified type of amine transfer reagent that addresses this limitation. This effort has enabled us to develop a CuH-catalyzed synthesis of chiral secondary amines using a variety of amine coupling partners, including those derived from amino acid esters, carbohydrates, and steroids. Mechanistic investigations indicated that the modified amine transfer reagents are less susceptible to direct reaction with CuH.
Synthesis of secondary amines via N-(benzoyloxy)amines and organoboranes
Phanstiel IV,Wang,Powell,Ospina,Leeson
, p. 803 - 806 (2007/10/03)
A variety of primary amines (R-NH2) were converted to their corresponding N-(benzoyloxy)amines (i.e., R-NHOCOPh) under biphasic conditions in excellent yields (63-90%). The intermediate N- (benzoyloxy)amines were converted to their N-ethylamine derivatives upon reaction with triethylborane in THF in good yield (54-89%). These experiments demonstrated the similar chemistry of N-chloro- and N-(benzoyloxy)amines with organoboranes.
A Study of Essentially Free Carbocations Derived via Diazonium and Oxo Diazonium Ions in the Liquid Phase
Darbeau, Ron W.,White, Emu H.,Song, Fenhong,Darbeau, Nyla R.,Chou, James
, p. 5966 - 5978 (2007/10/03)
Nitrogen- and nitrous oxide-separated ion pairs containing 4-substituted benzyl cations and carboxylate or tosylate anions were prepared by thermolysis of N-nitroso- and N-nitroamides, acidification of phenyldiazomethane, and nitrosation of N-benzyl-O-benzoylhydroxylamine. The cations were generated in benzene/toluene and benzene/anisole mixtures and were found to partition between the counterion and the solvent and between the aromatic cosolvent and benzene. A familial relationship among the methods was observed. As the cation became more reactive, the yield of solvent-derived products (SDPs) rose and the ratio of rate constants for its reaction with toluene versus benzene, kT/kB, fell. The yield of SDP also rose as the temperature was decreased and as N2 was replaced by N2O; however, kT/kB remained unchanged. Inert diluents had no effect on kT/kB but decreased hydrocarbon yield by 40% on 2-fold dilution. In the presence of reactive diluents that are converted into secondary alkylating agents, both the % hydrocarbon and kT/kB rose. These results are interpreted in terms of the intermediacy of inert-molecule-separated ion pairs (IMSIPs) in deamination. The cation reacted with benzoates and tosylates not only at the oxygens but also at the ipso carbon; subsequent decarboxylation and desulfonylation, respectively, led to diphenylmethanes. The ester/SDP ratio is introduced as a new measure of carbocation reactivity.
Nitrosation of the N-Alkyl-O-acylhydroxylamines. A New Deamination Method.
White, Emil H.,Ribi, Max,Cho, Lee K.,Egger, Notker,Dzadzic, Petar M.,Todd, Michael J.
, p. 4866 - 4871 (2007/10/02)
The nitrosation of N-alkyl-O-acylhydroxylamines leads to immediate decomposition at dry ice temperatures; the corresponding ester and nitrous oxide are formed.An 18O study has shown that the nitroso-O-acylhydroxylamines fragment directly rather than undergo a rearrangement reaction (as observed with the nitrosoamides).The product yields are respectable, especially at low tempreatures, and the method has promise for the generation of high energy carbonium ions.
