Iridium-Catalyzed Allylic Amination Research Articles

ChemInform Abstract: Enantioselective Construction of C‐Chiral Allylic Sulfilimines via the Iridium‐Catalyzed Allylic Amination with S,S‐Diphenylsulfilimine: Asymmetric Synthesis of Primary Allylic Amines.

We have devised a highly regio- and enantioselective iridium-catalyzed allylic amination reaction with the sulfur-stabilized aza-ylide, S,S-diphenylsulfilimine. This process provides a robust and scalable method for the construction of aryl-, alkyl- and alkenyl-substituted C-chiral allylic sulfilimines, which are important functional groups for organic synthesis. Additionally, the combination of the allylic amination with an in situ deprotection of the sulfilimine constitutes a convenient one-pot protocol for the construction of chiral nonracemic primary allylic amines.

Enantioselective construction of C-chiral allylic sulfilimines via the iridium-catalyzed allylic amination with S,S-diphenylsulfilimine: asymmetric synthesis of primary allylic amines.

We have devised a highly regio- and enantioselective iridium-catalyzed allylic amination reaction with the sulfur-stabilized aza-ylide, S,S-diphenylsulfilimine. This process provides a robust and scalable method for the construction of aryl-, alkyl- and alkenyl-substituted C-chiral allylic sulfilimines, which are important functional groups for organic synthesis. Additionally, the combination of the allylic amination with an in situ deprotection of the sulfilimine constitutes a convenient one-pot protocol for the construction of chiral nonracemic primary allylic amines.

Asymmetric synthesis of 2,5-disubstituted 3-hydroxypyrrolidines based on stereodivergent intramolecular iridium-catalyzed allylic aminations

Intramolecular iridium-catalyzed allylic aminations of homochiral (E)-6-N-nosylaminohept-2-en-1-yl methyl carbonates were investigated. The relative position of the 2,5-substituents of the resulting pyrrolidines was found to be controlled by using both enantiomers (4 and 5) of the appropriate chiral ligand, demonstrating a simple and highly stereodivergent synthetic protocol. Selected trans- and cis-2,5-disubstituted 3-hydroxypyrrolidines (2a and 18a) were converted to (+)-bulgecinine (6) and (+)-preussin (7), respectively.

Boron Medicinal Chemistry and Synthetic Aspects

Future Medicinal ChemistryVol. 5, No. 6 EditorialBoron medicinal chemistry and synthetic aspectsJonathan T Ahmet & John SpencerJonathan T AhmetDepartment of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton, East Sussex, BN1 9QJ, UKSearch for more papers by this author & John Spencer* Author for correspondenceDepartment of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton, East Sussex, BN1 9QJ, UK. Search for more papers by this authorEmail the corresponding author at j.spencer@sussex.ac.ukPublished Online:25 Apr 2013https://doi.org/10.4155/fmc.13.40AboutSectionsView ArticleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinkedInReddit View article"Boron medicinal chemistry and synthetic aspects." , 5(6), pp. 621–622Keywords: anticancer agentsbiosensorsC-C bond couplingenzyme inhibitorsReferences1 Hall DG, Ishiyama T, Miyaura N et al. 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John Wiley and Sons, Inc., NY, USA (1975).Google ScholarFiguresReferencesRelatedDetailsCited BySynthesis and antimicrobial properties of cyclic fluorodiamines containing boronate esters20 November 2017 | Heteroatom Chemistry, Vol. 28, No. 6Synthesis, characterization, and anticancer properties of iminophosphineplatinum(II) complexes containing boronate estersCanadian Journal of Chemistry, Vol. 95, No. 2Synthesis, Characterization, and Anticancer Activities of Pyrogallol-Based Arylspiroborates27 July 2015 | Journal of Heterocyclic Chemistry, Vol. 53, No. 6ChemInform Abstract: Boron Medicinal Chemistry and Synthetic Aspects1 July 2013 | ChemInform, Vol. 44, No. 29Focusing on boron in medicinal chemistryP Veeraraghavan Ramachandran25 April 2013 | Future Medicinal Chemistry, Vol. 5, No. 6 Vol. 5, No. 6 Follow us on social media for the latest updates Metrics Downloaded 170 times History Published online 25 April 2013 Published in print April 2013 Information© Future Science LtdKeywordsanticancer agentsbiosensorsC-C bond couplingenzyme inhibitorsFinancial & competing interests disclosureThe authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.No writing assistance was utilized in the production of this manuscript.PDF download

Enantioselective Syntheses of the Alkaloids cis-195A (Pumiliotoxin C) and trans-195A Based on Multiple Applications of Asymmetric Catalysis

Short enantio- and diastereoselective syntheses of the decahydroquinoline alkaloids cis- (pumiliotoxin C) and trans-195A are presented. Key steps are an enantioselective iridium-catalyzed allylic amination, a Suzuki-Miyaura coupling, a catalyst-controlled copper-catalyzed 1,4-addition, and a reductive amination.

Iridium-Catalyzed Allylic Amination Route to α-Aminoboronates: Illustration of the Decisive Role of Boron Substituents.

The development of a new route to α-aminoboronates using an iridium-catalyzed allylic amination on boronated substrates is described. Unlike the boronate group, the trifluoroborato substituent was found to govern the regioselectivity exclusively in favor of branched products. The transformation of an allylic substitution product into an α-aminoboronic ester in an efficient way validated the implementation of this approach.

Enantioselective Syntheses of 2,5‐Disubstituted Pyrrolidines Based on Iridium‐Catalyzed Allylic Aminations—Total Syntheses of Alkaloids from Amphibian Skins

A broadly applicable route to trans-2,5-disubstituted pyrrolidines has been developed. Key steps are an asymmetric iridium-catalyzed allylic amination, a Suzuki-Miyaura coupling, and an intramolecular aza-Michael addition. Enantiomeric excesses in the range of 93-99 % ee have been achieved. Total syntheses of the alkaloids (-)-225 C, (+)- and (-)-223 H (xenovenine), (+)-223 AB, (+)-195 B, and (+)-223 R have been carried out as applications.

Stereoselective Synthesis of syn- and anti-1,2-Aminoalcohols Using Iridium-Catalyzed Allylic Amination Reactions

A methodology for the stereoselective synthesis of syn- and anti-1,2-aminoalcohols, employing iridium-catalyzed amination reactions of allylic carbonates, was developed.

Enantioselective, Iridium-Catalyzed Monoallylation of Ammonia

Highly enantioselective, iridium-catalyzed monoallylations of ammonia are reported. These reactions occur with electron-neutral, -rich, and -poor cinnamyl carbonates, alkyl and trityloxy-substituted allylic carbonates, and dienyl carbonates in moderate to good yields and excellent enantioselectivities. This process is enabled by the use of an iridium catalyst that does not require a Lewis acid for activation and that is stable toward a large excess of ammonia. This selective formation of primary allylic amines allows for one-pot syntheses of heterodiallylamines and allylic amides that are not otherwise accessible via iridium-catalyzed allylic amination without the use of blocking groups and protective group manipulations.

Asymmetric Allylic Amination with Ammonia Equivalents

Building on their extensive studies of asymmetric iridium-catalyzed allylic aminations, the authors reported a practical method to synthesize primary allylic amine precursors 3 and 6. The reaction makes use of easily handled amine salts and low catalyst loadings to obtain the products in high ee. Further, a direct enantioselective allylation with ammonia was reported for the first time with a metal catalyst. The reaction yielded the secondary amine 7, which is a useful precursor for the synthesis of C 2-symmetric pyrrolidines.

Enantioselective Iridium-Catalyzed Allylic Amination of Ammonia and Convenient Ammonia Surrogates

Iridium-catalyzed, asymmetric allylation of ammonia as a nucleophile occurs with stereoselectivity to form a symmetric diallylamine, and related allylation of the inexpensive ammonia equivalent potassium trifluoroacetamide or the highly reactive ammonia equivalent lithium di-tert-butyliminodicarboxylate forms a range of conveniently protected, primary, alpha-branched allylic amines in high yields, high branched-to-linear regioselectivities, and high enantiomeric excess. The reactions of ammonia equivalents were conducted with a catalyst generated from a phosphoramidite containing a single stereochemical element.

Iridium‐Catalyzed Selective N‐Allylation of Hydrazines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Iridium-catalyzed selective N-allylation of hydrazines

A highly chemo- and regioselective iridium-catalyzed allylic amination is described. The reaction of various hydrazones and hydrazides with allylic carbonates proceeds at ambient temperature in the presence of an [Ir(COD)Cl] 2/pyridine catalyst, ammonium iodide, and diethylzinc to afford the corresponding N-allylation products in high yields with excellent chemo- and regioselectivities. Only the more nucleophilic nitrogen of a given hydrazine derivative undergoes the C–N bond formation to yield a branched allylic isomer as the exclusive product.

Identification of an activated catalyst in the iridium-catalyzed allylic amination and etherification. Increased rates, scope, and selectivity.

Studies were conducted to determine possible intermediates in the highly enantioselective, iridium-catalyzed amination and etherification of allylic carbonates, and these studies revealed that cyclometalation of the phosphoramidite ligand is likely to generate the active catalyst. The square-planar [Ir(COD)(L1)Cl] (L1 = P(BINOL)(bisphenethylamine)) did not react with cinnamyl carbonate, but did react with amine to generate an Ir(I) trigonal bipyramidal complex coordinated by COD, a cyclometalated kappa2-phosphoramidite, and a kappa1-phosphoramidite. This complex reacted with phosphines to generate products from replacement of the kappa1-phosphoramidite. These cyclometalated complexes were highly active catalysts for allylic amination and etherification and retained the high selectivity of the original catalyst system. In addition, these complexes combined with [Ir(cod)Cl]2 catalyzed reactions of amines with lower loadings, catalyzed reactions of alkylamines and aromatic amines that did not react with the original catalyst system, and catalyzed reactions of phenoxides under milder conditions.

Synthesis of Azacycles Basedon Iridium-Catalyzed Sequential Allylic Amination

The iridium-catalyzed sequential allylic amination of substrates having two allylic carbonate moieties proceeded smoothly, providing the novel method for synthesis of azacycles.