Synthesis Of Allylic Amines Research Articles

Integrated Approach for Allyl Amine Synthesis Combining the Decarboxylative Coupling of Arylacrylic Acids with the Petasis Reaction.

A metal-free multicomponent reaction strategy for synthesizing allyl amines through decarboxylative coupling combined with the Petasis reaction is described. Utilizing (E)-3-(2,4,6-trimethoxyphenyl)acrylic acid, various boronic acids, a formaldehyde solution, and primary amines, the method operates efficiently without metal catalysts. Investigations reveal that electron-donating substituents in cinnamic acid derivatives significantly enhance reactivity, which is crucial for effective transformations. Under the optimized conditions, yields of ≤78% were obtained across a diverse range of 30 allyl amines.

Tungsten-Catalyzed Regioselective Allylic Amination

AbstractA highly regioselective synthesis of allylic amines based on a tungsten-catalyzed allylic amination has been developed. This protocol, which is catalyzed by commercially available W(CO)3(MeCN)3 and 4,4′-di-tert-butyl-2,2′-bipyridine, permits the formation of synthetically useful branched allylic N-aryl- and N-alkylamines in moderate to good yields with a >20:1 branched/linear ratio under mild conditions. The noble-metal-free catalytic system complements conventional allylic aminations catalyzed by an Ir or Rh complex.

Merging of Light/Dark Palladium Catalytic Cycles Enables Multicomponent Tandem Alkyl Heck/Tsuji-Trost Homologative Amination Reaction toward Allylic Amines.

A visible light-induced palladium-catalyzed homologative three-component synthesis of allylic amines has been developed. This protocol proceeds via a unique mechanism involving two distinct cycles enabled by the same Pd(0) catalyst: a visible light-induced hybrid radical alkyl Heck reaction between 1,1-dielectrophile and styrene, followed by the "in dark" classical Tsuji-Trost-type allylic substitution reaction. This method works well with a broad range of primary and secondary amines, aryl alkenes, dielectrophiles, and in complex settings. The regiochemistry of the obtained products is primarily governed by the structure of 1,1-dielectrophile. Involvement of π-allyl palladium intermediates allowed for the control of stereoselectivity, which has been demonstrated with up to 95:5 er.

Synthesis of allylamines from Baylis–Hillman acetates using DBU under solvent free condition

Synthesis of allylamines from Baylis–Hillman acetates using DBU under solvent free condition

Pd‐Catalyzed Dehydrative Synthesis of Allylic Amines in Water

AbstractA mild Pd‐catalyzed Tsuji‐Trost reaction of allylic alcohols with an amine nucleophile in water media was developed, leading to the green synthesis of the valuable allylic amines. This new method requires no chemical activators and sophisticated soluble ligands, and can be easily scaled up in gram scale and be readily extended to the gram scale synthesis of Naftifine, one of the best‐selling antifungal drugs, showing the practical value of this new method.

Practical synthesis of allylic amines via nickel-catalysed multicomponent coupling of alkenes, aldehydes, and amides.

Molecules with an allylic amine motif provide access to important building blocks and versatile applications of biologically relevant chemical space. The need for diverse allylic amines requires the development of increasingly general and modular multicomponent reactions for allylic amine synthesis. Herein, we report an efficient catalytic multicomponent coupling reaction of simple alkenes, aldehydes, and amides by combining nickel catalysis and Lewis acid catalysis, thus providing a practical, environmentally friendly, and modular protocol to build architecturally complex and functionally diverse allylic amines in a single step. The method is remarkably simple, shows broad functional-group tolerance, and facilitates the synthesis of drug-like allylic amines that are not readily accessible by other methods. The utilization of accessible starting materials and inexpensive Ni(ii) salt as the alternative precatalyst offers a significant practical advantage. In addition, the practicality of the process was also demonstrated in an efficient, gram-scale preparation of the prostaglandin agonist.

Transition-metal-free, visible-light-induced multicomponent synthesis of allylic amines and tetrahydroquinolines

A visible-light-induced, 1,2,3,5-tetrakis-(carbazolyl)-4,6-dicyanobenzene (4CzIPN) catalyzed synthesis of allylic amines andtetrahydroquinolines through ‘all-alkyl’ α-amino radicals and anilinoalkyl radicals has been developed.

Electrochemical Synthesis of Allylic Amines from Terminal Alkenes and Secondary Amines

Allylic amines are valuable synthetic targets en route to diverse biologically active amine products. Current allylic C-H amination strategies remain limited with respect to the viable N-substituents. Herein, we disclose a new electrochemical process to prepare aliphatic allylic amines by coupling two abundant starting materials: secondary amines and unactivated alkenes. This oxidative transformation proceeds via electrochemical generation of an electrophilic adduct between thianthrene and the alkene substrates. Treatment of these adducts with aliphatic amine nucleophiles and base provides allylic amine products in high yield. This synthetic strategy is also amenable to functionalization of feedstock gaseous alkenes at 1 atm. In the case of 1-butene, high Z-selective crotylation is observed. This strategy, however, is not limited to the synthesis of simple building blocks; complex biologically active molecules are suitable as both alkene and amine coupling partners. Preliminary mechanistic studies implicate vinylthianthrenium salts as key reactive intermediates.

Palladium-Catalyzed [1,3]-O-to-N Rearrangement of Allylic ­Imidates

AbstractThe rearrangement of allylic imidates is a powerful transformation for the synthesis of allylic amines. Whereas the [3,3]-rearrangement has long been established as the Overman rearrangement, the corresponding [1,3]-rearrangement is rare. Here, we report a novel strategy for the [1,3]-rearrangement of imidates based on the oxidative addition of a palladium(0) catalyst to an allylic imidate. Structurally distinct allylic amides could be synthesized under mild and base-free conditions.

A Diastereodivergent and Enantioselective Approach to syn- and anti-Diamines: Development of 2-Azatrienes for Cu-Catalyzed Reductive Couplings with Imines That Furnish Allylic Amines.

We introduce a new reagent class, 2-azatrienes, as a platform for catalytic enantioselective synthesis of allylic amines. Herein, we demonstrate their promise by a diastereodivergent synthesis of syn- and anti-1,2-diamines through their Cu-bis(phosphine)-catalyzed reductive couplings with imines. With Ph-BPE as the supporting ligand, anti-diamines are obtained (up to 91% yield, >20:1 dr, and >99:1 er), and with the rarely utilized t-Bu-BDPP, syn-diamines are generated (up to 76% yield, 1:>20 dr, and 97:3 er).

Direct Synthesis of Allyl Amines with 2-Nitrosulfonamide Derivatives via the Tsuji-Trost Reaction.

The Tsuji‐Trost Reaction is a palladium‐catalysed allylation of nucleophiles that consists in the reaction of a nitrogen, carbon or oxygen‐based nucleophiles with an allylic substrate bearing a leaving group. Here we present the use of 2‐nitrosulfonamide derivatives as nucleophile, which are reactive under mild conditions. 2‐nitrosulfonyl groups are well‐known dual protective activator groups easy to introduce in any type of amine substrates. The resulting 2‐nitrosulfonamide derivatives are ideal substrates for the Tsuji‐Trost reaction to afford a convenient and flexible access to primary and dissymmetric secondary allyl amines. The optimised procedure is flexible (for solvent, temperature, functional groups) and has been applied with good to excellent yield to access to a wide range of allyl amine derivatives.

NbCl5-Mg Reagent System in Regio- and Stereoselective Synthesis of (2Z)-Alkenylamines and (3Z)-Alkenylols from Substituted 2-Alkynylamines and 3-Alkynylols.

The reduction of N,N-disubstituted 2-alkynylamines and substituted 3-alkynylols using the NbCl5–Mg reagent system affords the corresponding dideuterated (2Z)-alkenylamine and (3Z)-alkenylol derivatives in high yields in a regio- and stereoselective manner through the deuterolysis (or hydrolysis). The reaction of substituted propargylamines and homopropargylic alcohols with the in situ generated low-valent niobium complex (based on the reaction of NbCl5 with magnesium metal) is an efficient tool for the synthesis of allylamines and homoallylic alcohols bearing a 1,2-disubstituted double bond. It was found that the well-known approach for the reduction of alkynes based on the use of the TaCl5-Mg reagent system does not work for 2-alkynylamines and 3-alkynylols. Thus, this article reveals a difference in the behavior of two reagent systems—NbCl5-Mg and TaCl5-Mg, in relation to oxygen- and nitrogen-containing alkynes. A regio- and stereoselective method was developed for the synthesis of nitrogen-containing E-β-chlorovinyl sulfides based on the reaction of 2-alkynylamines with three equivalents of methanesulfonyl chloride in the presence of stoichiometric amounts of niobium(V) chloride and magnesium metal in toluene.

Zirconium-Catalyzed Hydroaminoalkylation of Alkynes for the Synthesis of Allylic Amines.

A zirconium-catalyzed hydroaminoalkylation of alkynes to access α,β,γ-substituted allylic amines in an atom-economic fashion is reported. The reaction is compatible with N-(trimethylsilyl)benzylamine and a variety of N-benzylaniline substrates, with the latter giving the allylic amine as the sole organic product. Various internal alkynes with electron-withdrawing and electron-donating substituents were tolerated. Model intermediates of the reaction were synthesized and structurally characterized. Stoichiometric studies on key intermediates revealed that the open coordination sphere at zirconium, imparted by the tethered bis(ureate) ligand, is crucial for the coordination of neutral donors. These complexes may serve as models for the inner-sphere protonolysis reactions required for catalytic turnover.

Alkenyl Exchange of Allylamines via Nickel(0)-Catalyzed C-C Bond Cleavage.

A functional group exchange reaction between allylamines and alkenes via nickel-catalyzed C-C bond cleavage and formation was developed. This reaction provides a novel protocol, which does not require the use of unstable imine substrates, for the synthesis of allylamines, which are widely used in the production of fine chemicals, pharmaceuticals, and agrochemicals.

Iron‐Catalyzed Synthesis of Amines and Thioethers Directly from Allylic Alcohols

AbstractA straightforward and efficient approach for the synthesis of allylic amines and thioethers has been developed by an iron‐catalyzed cross‐coupling reaction using diphosphite ligand. The reaction between allylic alcohols and amines/thiols gave allylic amine and thioester. The method is compatible with various functional groups, affording products with high yield and monoallylation selectivity.

Synthesis of Allylic Amines by Asymmetric Transfer Hydrogenation of α,β-Unsaturated N-(tert-Butylsulfinyl)imines.

Primary allylic amines with enantiomeric excesses from 97 to >99% were prepared by asymmetric transfer hydrogenation of α,β-unsaturated N-(tert-butylsulfinyl)ketimines followed by removal of the sulfinyl group. The effect caused by different substituents at the C═C bond and at the iminic carbon atom on the chemoselectivity of the reduction was studied. The desired enantiomer of the final allylic amine can be synthesized by choosing the sulfinyl group with the appropriate absolute configuration.

Stereoselective Synthesis of Allylamines from Trichloroacetimidates

Stereoselective Synthesis of Allylamines from Trichloroacetimidates

A metagenomics approach for new biocatalyst discovery: application to transaminases and the synthesis of allylic amines

A metagenomics mining strategy was used to identify new transaminases that were utilised in the synthesis of allylic amines.

Stereoselective and Versatile Preparation of Tri- and Tetrasubstituted Allylic Amine Scaffolds under Mild Conditions.

Significant progress has been observed in recent years in the synthesis of allylic amines, which are important building blocks in synthetic chemistry. Most of these processes are effective toward the preparation of allylic amines, with limited potential to introduce three or four different substituents on the olefinic unit in a stereocontrolled fashion. Therefore, the discovery of a mild and operationally simple protocol allowing such challenging stereoselective synthesis of multisubstituted allylic amines remains an inspiring target. Herein, we report the first general and practical methodology for the stereoselective synthesis of tri- and tetrasubstituted allylic amines based on Pd-catalyzed conversion of allyl surrogates readily obtained from cyclic vinyl carbonates. These rare conversions are characterized by excellent stereoselectivity, operational simplicity, mild reaction conditions, and wide scope in reaction partners. DFT studies were performed to rationalize the stereocontrol in these allylic amine formation reactions, and evidence is provided that the formation of a six-membered palladacyclic intermediate leads toward the formation of (Z)-configured allylic amine products.

Recent Developments in Asymmetric Allylic Amination Reactions

The asymmetric synthesis of allylic amines is an important research area in modern synthetic organic chemistry, primarily due to the inherent utility and ubiquity of this functional group in various synthetic intermediates and bioactive agents. For instance, a plethora of methods for the stereocontrolled construction of allylic amines now provides a vibrant array of strategies for the installation of this important functionality. This review highlights developments in the field since 1998 through the provision of the most important methods and their mechanistic aspects in order to provide insight into their current scope and limitations. Hence, we envisage it will be an essential guide to the current state-of-the-art for this important area, which highlights potential new opportunities for further developments. 1 Introduction 2 Allylic Substitution 2.1 Transition Metal Catalyzed via a π-Allyl Intermediate 2.2 Lewis Base Catalyzed 2.3 Azametallation/Elimination 2.4 Miscellaneous 3 Sigmatropic Rearrangements 3.1 [3,3]-Rearrangement 3.2 [2,3]-Rearrangement 3.3 Curtius Rearrangement 4 Amination of Alkenes 4.1 Hydroamination 4.2 Carboamination 4.3 Diamination 5 Wacker-Type Oxidative Amination 6 C–H Functionalization 7 Electrophilic Amination 8 Conclusions