An Electrochemical Cinnamyl C—H Amination Reaction Using Carbonyl Sulfamate

An electrochemical cinnamyl C—H amination reaction in the absence of transition metal catalyst and oxidant was reported. The choice of carbonyl sulfamate as nitrogen source is the key to achieve desired chemoselectivity. A series of terminal amine derivatives are prepared using this protocol and the sulfonyl group can be removed with basic hydrolysis. The reaction is suggested to proceed via a continuous anodic oxidation, deprotonation, anodic oxidation, and intermolecular nucleophilic addition pathway, demonstrating the first example of electrochemical cinnamyl C—H amination.     

Oxidative Pd(II)-catalyzed C-H bond amination to carbazole at ambient temperature

We report a new Pd(II)-catalyzed C-H bond amination reaction to form carbazoles, an important motif that is prevalent in a range of systems. The catalytic amination process operates under extremely mild conditions and produces carbazole products in good to excellent yields. Carbazoles possessing complex molecular architecture can also be formed using this reaction, highlighting its potential in natural product synthesis applications. Preliminary mechanistic investigations reveal the reaction proceeds through a Pd(II)/Pd(IV) manifold and that reductive elimination from a high oxidation state Pd(IV) complex facilitates the mild conditions of this transformation.     

Practical Approach for Synthesis of 2-Amino-benzoxazole in Water

A practical copper-catalyzed amination of benzoxazole with secondary amine in water has been developed. This reaction has proved to be effective to some cyclic amines, and the substituted group of nitrogen has a great impact on the amination reaction. A copper-catalyzed/ amine-induced ring opening of the benzoxazole and recyclization/oxidation mechanism was also proposed.     

Asymmetric Catalytic Preparation of Polysubstituted Cyclopropanol and Cyclopropylamine Derivatives

The catalytic asymmetric carbometalation of cyclopropenes followed by either an electrophilic oxidation or amination reaction provides a unique approach to the formation of diastereomerically pure and enantiomerically enriched cyclopropanol and cyclopropylamine derivatives, respectively.     

Towards Uniform Iodine Catalysis: Intramolecular C−H Amination of Arenes under Visible Light

A photochemical catalytic amination of arenes is presented. The reaction proceeds under benign iodine catalysis in the presence of visible light as the initiator and provides access to a range of differently substituted arylamines. A total of 29 examples demonstrate the broad applicability of this mild oxidation method. The scope of the reaction could further be expanded to silyl‐tethered derivatives, which undergo intramolecular amination upon formation of seven‐membered heterocycles. Cleavage of the silicon tether provides access to the corresponding 3‐substituted anilines.     

Metal-free one-pot oxidative amination of aldehydes to amides

Metal-free oxidative amination of aromatic aldehydes in the presence of TBHP provides convenient access to amides in 85-99% under mild reaction conditions within 5 h. This method avoids free carboxylic acid intermediates and integrates aldehyde oxidation and amide bond formation, which are usually accomplished separately, into a single operation. Proline-derived amides can be prepared in excellent yields without noticeable racemization.     

Synthesis and characterization of p-phenylenediamine derivatives bearing an electron-acceptor unit

[reaction: see text] Two series of aniline oligomers bearing fused heterocycles as an electron-acceptor unit were synthesized. They consist of aniline or its derivatives as an electron donor and benzothiadiazole (BT) or quinoxaline (QX) as an electron-acceptor unit. Benzothiadiazoles 1-3 were synthesized by palladium-catalyzed amination. Quinoxalines 4-6 were prepared by palladium-catalyzed amination or transformation from the benzothiadiazoles. These compounds showed a HOMO-LUMO gap smaller than those of their analogues such as thiophene-substituted BT/QXs. Cyclic voltammetry revealed that the electrochemical behavior is dependent on the position of the acceptor heterocycle. Chemical oxidation with Ag2O afforded the corresponding 1,4-quinonediimine derivatives as an E,E-isomer, stereoselectively. As for the BT pentamer analogues 2 and 3, the first oxidation selectively occurred at the amino group adjacent to the benzothiadiazole unit, giving the regiospecific half-oxidized derivatives. Furthermore, the fully oxidized derivative 24 was isolated and characterized.     

Direct amination of isobutylene over zeolite catalysts with various topologies and acidities

The atomically economic and green chemical reaction of direct amination of isobutylene to tertbutylamine, particularly under the relative mild reaction conditions available for future industrial use,was carried out over zeolite catalysts possessing different topological structures, from one dimensional to three dimensional pore system, and from small 8-member ring pore(MRP) to medium 10 MRP and further to large 12 MRP zeolites, to disclose the relationship between the zeolite properties/topologies and their amination performance systematically under the mild reaction conditions. It was discovered that the pore structure and the acidities of zeolite catalysts played crucial roles in the isobutylene amination process, and suitable pore diameter(larger than 0.5 nm or with large side pockets/cups in the outside surface) and a certain number of mid-strong acid sites are indispensable to catalyze the amination reaction,while too strong acid strength was not conducive to the process of isobutylene amination. Among them,zeolites with topologies of BEA, MFI, MEL, MWW and EUO exhibited good amination performance, with which the isobutylene conversion was higher than 12.61%(46.42% of the equilibrium conversion) under the studied mild reaction conditions. Due to the good amination performance and the large adjustable Si/Al_2 ratio range, ZSM-5 was selected to further study the effect of acidity on the amination performance systematically under the mild reaction conditions, and the activity-acidity relationship in the amination process was disclosed: the amination activity(isobutylene conversion) had a linear correlation with the amount of mid-strong B acidity under the studied conditions over ZSM-5 catalyst, which can provide guidance for further developing high-efficient amination catalyst under mild reaction conditions available for future industrial use.     

Mild and efficient copper-catalyzed amination of aryl bromides with primary alkylamines

[reaction: see text] An efficient copper-catalyzed amination of aryl bromides with primary alkylamines was developed that uses commercially available diethylsalicylamide as the ligand. This amination reaction can be performed at 90 degrees C in good yield. A variety of functional groups are compatible with these reaction conditions. Preliminary results show that this reaction can be carried out under solvent-free conditions with comparable yields.     

Intermolecular Ritter-type C-H amination of unactivated sp3 carbons

Intermolecular Ritter-type C-H amination of unactivated sp(3) carbons has been developed. This new reaction proceeds under mild conditions using readily available reagents and an inexpensive source of nitrogen (acetonitrile). A broad scope of substrates can be aminated with this method since many functional groups are tolerated. This reaction also allows for the direct, innate C-H amination of a variety of hydrocarbons such as cyclohexane without the need of prefunctionalization or installation of a directing group.     

Copper-Catalyzed Aerobic Oxidation for the Amination of Benzoxazole Under Air

A practical copper-catalyzed aerobic oxidation for the amination of benzoxazole with secondary amine has been discovered. This reaction has proved to be effective to a variety of amines with lower catalyst loading amount, and only oxygen in air is required to facilitate this transformation. A copper-catalyzed/amine-induced ring opening of the benzoxazole and recyclization mechanism was also proposed.     

Electrophilic amination of 4-fluorophenol with diazenes: a complete removal of the fluorine atom

The electrophilic amination of 2-fluorophenol, 4-fluorophenol, and 2-chlorophenol was observed to occur as a result of their treatment with diazenes 1-4 under mild reaction conditions in the presence of ZrCl(4). The products originating from the 2-fluorophenol or 2-chlorophenol can be considered as "normal" products of amination. On the other hand, the 2-chloro-4-amino-substituted phenols obtained from the 4-fluorophenol seem to be formed in a process that involves an ipso amination, the complete removal of the fluorine atom, and the introduction of the chlorine atom.     

Rhodium(II)-Catalyzed Selective C(sp3)−H Amination of Alkanes

The development of an efficient catalytic system enabling the conversion of alkanes to valuable nitrogen-containing building blocks is reported. Light alkanes can be selectively functionalized by an intermolecular C(sp³)−H amination reaction that proceeds at room temperature in the presence of only 1 mol % of a dirhodium(II) complex. Selective amination of tertiary C(sp³)−H within acyclic or cyclic alkanes used as limiting components leads to the corresponding amides isolated with yields in the 51–96 % range. The reaction, that can be performed on a gram-scale, applies with equal levels of efficiency and selectivity to more complex hydrocarbons.     

α-Amination of Aldehydes Catalyzed by In Situ Generated Hypoiodite

The metal-free amination of different aldehydes is catalyzed by hypoiodite, which is generated by employing commercially available sodium percarbonate as the co-oxidant. This approach has several advantages: it is a metal-free oxidation that works under mild reaction conditions; furthermore, it has a wide substrate scope and does not give toxic by-products from the co-oxidant that is used.     

Heterogeneously Porous γ‐MnO2‐Catalyzed Direct Oxidative Amination of Benzoxazole through CH Activation in the Presence of O2

Oxidative amination of azoles through catalytic C? H bond activation is a very important reaction due to the presence of 2‐aminoazoles in several biologically active compounds. However, most of the reported methods are performed under homogeneous reaction conditions using excess reagents and additives. Herein, we report the heterogeneous, porous γ‐MnO₂‐catalyzed direct amination of benzoxazole with wide range of primary and secondary amines. The amination was carried under mild reaction conditions and using molecular oxygen as a green oxidant, without any additives. The catalyst can easily be separated by filtration and reused several times without a significant loss of its catalytic performance. Of note, the reaction tolerates a functional group such as alcohol, thus indicating the broad applicability of this reaction.     

Chemical transformations of betulonic aldehyde

Chemical transformations of 3-oxolup-20(29)-en-28-al in oxidation, reduction, reductive amination, aldol crotonic condensation, cyclopropanation, Grignard, and Wittig reactions were investigated. The structure of reaction products was established by X-ray diffraction (XRD) analysis.     

Diporphyrinylamines: synthesis and electrochemistry

The synthesis of three possible diporphyrinylamines is described. All compounds were obtained by using the Buchwald-Hartwig aromatic amination reaction. The electronic spectra of the three porphyrin dimers showed characteristic features found in highly delocalized systems. The first oxidation of these compounds took place on the connecting amine function.     

脯氨酸催化的不对称有机反应

脯氨酸作为一种结构简单、商品化的、廉价小分子手性催化剂,在多种不对称催化反应中表现出非常好的催化性能,本文综述了近年来脯氨酸直接催化的不对称有机反应涉及Aldol反应,Mannich反应,Michael反应,Diels-Alder反应,直接α-胺化反应,α-氧胺化反应,Baylis-Hillman反应,还原反应和氧化反应的进展并展望了其应用前景。     

Metal‐ and Base‐Free Room‐Temperature Amination of Organoboronic Acids with N‐Alkyl Hydroxylamines

We have found that readily available N‐alkyl hydroxylamines are effective reagents for the amination of organoboronic acids in the presence of trichloroacetonitrile. This amination reaction proceeds rapidly at room temperature and in the absence of added metal or base, it tolerates a remarkable range of functional groups, and it can be used in the late‐stage assembly of two complex units.     

Use of polymer-supported dialkylphosphinobiphenyl ligands for palladium-catalyzed amination and Suzuki reactions

The preparations of polymer-supported dialkylphosphinobiphenyl ligands (3) are reported. A palladium catalyst based on ligand 3a is active for amination and Suzuki reactions using unactivated aryl iodides, bromides, or chlorides. Filtration of the catalyst from the reaction mixture allows for simplified product isolation via an aqueous workup. The resin-bound catalyst can be recycled without additional palladium in both the amination and Suzuki reactions.