Simplified Modular Access to Enantiopure 1,2-Aminoalcohols via Ni-Electrocatalytic Decarboxylative Arylation

Chiral aminoalcohols are omnipresent in bioactive compounds. Conventional strategies to access this motif involve multiple-step reactions to install the requisite functionalities stereoselectively using conventional polar bond analysis. This study reveals that a simple chiral oxazolidine-based carboxylic acid can be readily transformed to substituted chiral aminoalcohols with high stereochemical control by Ni-electrocatalytic decarboxylative arylation. This general, robust, and scalable coupling can be used to synthesize a variety of medicinally important compounds, avoiding protecting and functional group manipulations, thereby dramatically simplifying their preparation.

Visible-Light-Driven Multicomponent Diamination and Oxyamination of Alkene

Herein, we describe an effective method for the synthesis of 2-alkoxyamides and 1,2-diamines through visible-light-mediated difunctionalization of alkenes. N-Aminopyridinium salts were employed as appropriate precursors to generate key amidyl radical intermediates via a photoinduced single-electron transfer (SET) process. The amidyl radicals would react with alkenes, followed by oxidation and nucleophilic addition. Excellent functional group tolerance and good yields demonstrate the synthetic potential of this transformation.

Intramolecular Carboxyamidation of Alkyne-Tethered O-Acylhydroxamates through Formation of Fe(III)-Nitrenoids

We developed intramolecular carboxyamidations of alkyne-tethered O-acylhydroxamates followed by either thermally induced spontaneous or 4-(dimethylamino)pyridine-catalyzed O→O or O→N acyl group migration. Under iron-catalyzed conditions, the carboxyamidation products were generated in high yield from both Z-alkene and arene-tethered substrates. DFT calculations indicate that the iron-catalyzed carboxyamidation proceeds via a stepwise mechanism involving iron-imidyl radical cyclization followed by intramolecular acyloxy transfer from the iron center to the alkenyl radical center to furnish the cis-carboxyamidation product. Upon treatment with 4-(dimethylamino)pyridine, the Z-alkene-tethered carboxyamidation products underwent selective O→O acyl migration to generate 2-acyloxy-5-acyl pyrroles. Thermal O→N acyl migration occurs during carboxyamidation if the Z-alkene linker contains an alkyl or an aryl substituent at the β-position of the carbonyl group. On the other hand, the arene linker-containing compounds selectively undergo O→N acyl migration to generate N-acyl-3-acylisoindolinones, and the corresponding O→O acyl migration forming isoindole derivatives was not observed.

Parallel kinetic resolution of aziridines via chiral phosphoric acid-catalyzed apparent hydrolytic ring-opening

We report a chiral phosphoric acid catalyzed apparent hydrolytic ring-opening reaction of racemic aziridines in a regiodivergent parallel kinetic resolution manner. Harnessing the acyloxy-assisted strategy, the highly stereocontrolled nucleophilic ring-opening of aziridines with water is achieved. Different kinds of aziridines are applicable in the process, giving a variety of enantioenriched aromatic or aliphatic amino alcohols with up to 99% yields and up to >99.5 : 0.5 enantiomeric ratio. Preliminary mechanistic study as well as product elaborations were inducted as well.

The diacetyliminoxyl radical in oxidative functionalization of alkenes

The intermolecular oxime radical addition to CC bonds was observed and studied for the first time. The diacetyliminoxyl radical was proposed as a model radical reagent for the study of oxime radical reactivity towards unsaturated substrates, which is important in the light of the active development of synthetic applications of oxime radicals. In the present work it was found that the diacetyliminoxyl radical reacts with vinylarenes and conjugated dienes to give radical addition products, whereas unconjugated alkenes can undergo radical addition or allylic hydrogen substitution by diacetyliminoxyl depending on the substrate structure. Remarkably, substituted alkenes give high yields of C-O coupling products despite the significant steric hindrance, whereas unsubstituted alkenes give lower yields of the C-O coupling products. The observed atypical C-O coupling yield dependence on the alkene structure was explained by the discovered ability of the diacetyliminoxyl radical to attack alkenes with the formation of a C-N bond instead of a C-O bond giving side products. This side process is not expected for sterically hindered alkenes due to lower steric availability of the N-atom in diacetyliminoxyl than that of the O-atom.

Conceptual advances in nucleophilic organophosphine-promoted transformations

Catalysis by trivalent nucleophilic organophosphines has emerged as an essential tool in organic synthesis. Several new organic transformations promoted by phosphines substantiate and complement the existing synthetic chemistry tools. Mere design of the substrate and reagent combinations has introduced new modes of reactivity patterns, which are otherwise difficult to achieve. These design considerations have led to the rapid build-up of complex molecular entities and laid a solid foundation to synthesise bioactive natural products and pharmaceuticals. This article presents an overview of some of the conceptual advances, including our contributions to nucleophilic organophosphine chemistry. The scope, limitations, mechanistic insights, and applications of these metal-free transformations are discussed elaborately.

Rhodium-Catalyzed Enantioselective 1,4-Oxyamination of Conjugated gem-Difluorodienes via Coupling with Carboxylic Acids and Dioxazolones

The incorporation of fluorine atoms in organics improves their bioactivity and lipophilicity. Catalytic functionalization of gem-difluorodienes represents one of the most straightforward approaches to access fluorinated alkenes. In contrast to the regular 1,3-dienes that undergo diverse asymmetric di/hydrofunctionalizations, the regio- and enantioselective oxyamination of gem-difluorodienes remains untouched. Herein, we report asymmetric 1,4-oxyamination of gem-difluorodiene by chiral rhodium-catalyzed three-component coupling with readily available carboxylic acid and dioxazolone, affording gem-difluorinated 1,4-amino alcohol derivatives. Our asymmetric protocol exhibits high 1,4-regio- and enantioselectivity with utility in the late-stage modification of pharmaceuticals and natural products. Stoichiometric experiments provide evidences for the π-allylrhodium pathway. Related oxyamination was also realized when trifluoroethanol was used as an oxygen nucleophile.

Electrochemical Oxidation Enables Regioselective 1,3-Hydroxyfunctionalization of Cyclopropanes

The direct construction of 1,3-hydroxyfunctionalized molecules is still a significant challenge, as they can currently be obtained through multiple synthetic steps. Herein, we report a general and efficient 1,3-hydroxyfunctionalization of arylcyclopropanes by electrochemical oxidation with a strategic choice of nucleophiles and H2O. 1,3-Amino alcohols, 1,3-alkynyl alcohols, 1,3-hydroxyesters, and 1,3-halo alcohols are achieved with high levels of chemo- and regio-selectivity, opening a new dimension for 1,3-difunctionalization reaction.

Photoinduced copper-catalyzed selective three-component 1,2-amino oxygenation of 1,3-dienes

This study presents a highly effective method for the photoinduced copper-catalyzed 1,2-amino oxygenation of 1,3-dienes. This synthetic strategy involves the dual roles of a single copper catalyst, which can act as a photosensitizer to generate nitrogen radicals and can also react with allyl radicals via single electron transfer (SET) processes. The method produces a range of quaternary carbon-centered allyl carboxylic esters and tertiary ethers with high yields and excellent regioselectivity under mild reaction conditions.

Visible-Light-Driven C-H Imidation of Arenes and Heteroarenes by a Phosphonium Ylide Organophotoredox Catalyst: Application to C-H Functionalization of Alkenes

Phosphonium ylide catalysis through an oxidative quenching cycle has been developed for visible-light-driven C-H imidation of arenes and heteroarenes. The present protocol could be applied not only to trihalomethylative lactonization reactions involving trifluoromethyl, trichloromethyl, and tribromomethyl radicals but also to the first example of an organophotoredox-catalyzed imidative lactonization reaction involving a nitrogen-centered electrophilic radical species.

Cu-Catalyzed Double C(sp3)-H Functionalization of Ethylarenes to Form Arylethanolamines

A double C(sp³)-H functionalization of ethylarenes with alcohols and N-fluorobenzenesulfonimide is reported. The reaction proceeds in three stages. (1) Cu-catalyzed benzylic alkoxylation of ethylarenes gives 1-(1-alkoxyethyl)benzenes. (2) The resulting 1-(1-alkoxyethyl)benzenes are gradually converted into vinylarenes. (3) Cu-catalyzed aminoalkoxylation of the intermediary vinylarenes yields arylethanolamines. Overall, the C-N and C-O bonds are introduced regioselectively at the homobenzylic and benzylic positions of ethylarenes.

Regiospecific Alkene Aminofunctionalization via an Electrogenerated Dielectrophile

Modular strategies to rapidly increase molecular complexity have proven immensely synthetically valuable. In principle, transformation of an alkene into a dielectrophile presents an opportunity to deliver two unique nucleophiles across an alkene. Unfortunately, the selectivity profiles of known dielectrophiles have largely precluded this deceptively simple synthetic approach. Herein, we demonstrate that dicationic adducts generated through electrolysis of alkenes and thianthrene possess a unique selectivity profile relative to more conventional dielectrophiles. Specifically, these species undergo a single and perfectly regioselective substitution reaction with phthalimide salts. This observation unlocks an appealing new platform for aminofunctionalization reactions. As an illustrative example, we implement this new reactivity paradigm to address a longstanding synthetic challenge: alkene diamination with two distinct nitrogen nucleophiles. Studies into the mechanism of this process reveal a key alkenyl thianthrenium salt intermediate that controls the exquisite regioselectivity of the process and highlight the importance of proton sources in controlling the reactivity of alkenyl sulfonium salt electrophiles.

Construction of oxygenated 2-azabicyclo[2.2.1]heptanes via palladium-catalyzed 1,2-aminoacyloxylation of cyclopentenes

Herein, we describe a palladium-catalyzed 1,2-aminoacyloxylation of cyclopentenes to synthesize oxygenated 2-azabicyclo[2.2.1]heptanes. This reaction proceeds efficiently with a broad array of substrates. The products could be further functionalized to build up a library of bridged aza-bicyclic structures.

Iron-Catalyzed Intermolecular Oxyamination of Terminal Alkenes Promoted by HFIP Using Hydroxylamine Derivatives

An atom-economical intermolecular iron-catalyzed oxyamination of alkenes is described herein. The insertion of oxygenated and nitrogenated moieties from the hydroxylamine substrate was observed with full regio- and chemo-selectivity for terminal alkenes in good yields. HFIP as a solvent appeared to have a synergistic effect with the iron catalyst to promote the formation of the oxyaminated products. Preliminary mechanistic studies suggest a pathway going through an aziridination reaction followed by an in situ ring opening.

Covalent Tethers for Precise Amino Alcohol Syntheses: Ring Opening of Epoxides by Pendant Sulfamates and Sulfamides

We describe the development of the first ring opening of epoxides using pendant sulfamates and sulfamides. These reactions are promoted by a base and proceed under mild conditions to afford oxathiazinanes and cyclic sulfamides with excellent diastereoselectivity and regiocontrol. The reactions scale well, and the products serve as synthons for ring-opening reactions.

Cycloisomerization of Alkyne-Tethered N-Acyloxycarbamates to 2-(3H)Oxazolones through Nitrenoid-Mediated Carboxyamidation

The cycloisomerization of alkyne-tethered N-benzoyloxycarbamates to 2-(3H)oxazolones is described. Two catalytic systems are tailored for intramolecular 5-exo-alkyne carboxyamidation and concomitant alkene isomerization. PtCl₂ /CO (5 mol%, toluene, 100 °C) promotes both carboxyamidation and alkene isomerization but has a limited substrate scope. On the other hand, FeCl₃ (5 mol%, CH₃ CN, 100 °C) promotes carboxyamidation effectively but a cocatalyst is required for the exocyclic alkene isomerization. Thus, a two-step one-pot protocol has been developed for a broader reaction scope, which involves FeCl₃ -catalyzed carboxyamidation and base-induced alkene isomerization. Crossover experiments suggest that these reactions proceed mainly through a mechanism involving acylnitrenoid intermediates rather than carbenoid intermediates.

Chemoselective and Enantioselective Fluorescent Recognition of Prolinol

A highly chemoselective and enantioselective fluorescent probe has been discovered for the recognition of prolinol among various primary and secondary amine-based amino alcohols. The mechanistic studies including 1D and 2D ¹H/¹³C NMR and mass spectroscopic analyses and DFT calculations have shown that the aldehyde group of the probe can react with prolinol to generate a bicyclic oxazolidine unit which, through a possible intramolecular hydrogen bond interaction, will lead to highly selective fluorescence enhancement.

Kukhtin-Ramirez-Reaction-Inspired Deprotection of Sulfamidates for the Synthesis of Amino Sugars

Herein, we present a mild strategy for deprotecting cyclic sulfamidates via the Kukhtin-Ramirez reaction to access amino sugars. The method features the removal of the sulfonic group of cyclic sulfamidates, which occurs through an N-H insertion reaction that implicates the Kukhtin-Ramirez adducts, followed by a base-promoted reductive N-S bond cleavage. The mild reaction conditions of the protocol enable the formation of amino alcohols including analogs that bear multiple functional groups.

Highly Selective Radical Relay 1,4-Oxyimination of Two Electronically Differentiated Olefins

Radical addition reactions of olefins have emerged as an attractive tool for the rapid assembly of complex structures, and have plentiful applications in organic synthesis, however, such reactions are often limited to polymerization or 1,2-difunctionalization. Herein, we disclose an unprecedented radical relay 1,4-oxyimination of two electronically differentiated olefins with a class of bifunctional oxime carbonate reagents via an energy transfer strategy. The protocol is highly chemo- and regioselective, and three different chemical bonds (C-O, C-C, and C-N bonds) were formed in a single operation in an orchestrated manner. Notably, this reaction provides rapid access to a large variety of structurally diverse 1,4-oxyimination products, and the obtained products could be easily converted into valuable biologically relevant δ-hydroxyl-α-amino acids. With a combination of experimental and theoretical methods, the mechanism for this 1,4-oxyimination reaction has been investigated. Theoretical calculations reveal that a radical chain mechanism might operate in the reaction.

Regiodivergent Electrophotocatalytic Aminooxygenation of Aryl Olefins

A method for the regiodivergent aminooxygenation of aryl olefins under electrophotocatalytic conditions is described. The procedure employs a trisaminocyclopropenium (TAC) ion catalyst with visible light irradiation under a controlled electrochemical potential to convert aryl olefins to the corresponding oxazolines with high chemo- and diastereoselectivity. With the judicious choice between two inexpensive and abundant reagents, namely water and urethane, either 2-amino-1-ol or 1-amino-2-ol derivatives could be prepared from the same substrate. This method is amenable to multigram synthesis of the oxazoline products with low catalyst loadings.

Ring Opening of Aziridines by Pendant Silanols Allows for Preparations of (±)-Clavaminol H, (±)-Des-Acetyl-Clavaminol H, (±)-Dihydrosphingosine, and (±)-N-Hexanoyldihydrosphingosine

We present a unique strategy for the synthesis of vicinal amino alcohols. Ring opening of aziridines with pendant silanols is compatible with a range of substrates. To engage productively in ring opening, the aziridine must be at least mildly activated, and a variety of such N-substituents are tolerated. The utility of this methodology is highlighted in facile preparations of the natural products (±)-Clavaminol H, (±)-dihydrosphingosine, and (±)-N-hexanoyldihydrosphingosine as well as a natural product analogue (±)-des-acetyl-Clavaminol H.

Rh(III)-catalyzed Intra- and Intermolecular 3,4-Difunctionalization of 1,3-Dienes via Rh(III)-π-allyl Amidation with 1,4,2-Dioxazolones

We herein report a modular strategy, which enables Rh(III)-catalyzed diastereoselective 3,4-amino oxygenation and diamination of 1,3-dienes using different O- and N-nucleophiles in combination with readily available 3-substituted 1,4,2-dioxazolones (78 examples, 37-91% yield). Previous attempts to functionalize the internal double bond rested on the use of plain alcoholic solvents as nucleophilic coupling partners thus dramatically limiting the scope of this transformation. We have now identified hexafluoroisopropanol as a non-nucleophilic solvent which allows the use of diverse nucleophiles and greatly expands the scope, including an unprecedented amino hydroxylation to selectively install valuable, unprotected β-amino alcohols across 1,3-dienes. Moreover, various elaborate alcohols prove to be compatible providing unique access to complex organic molecules. Finally, this method is employed in a series of intramolecular reactions to deliver valuable nitrogen heterocycles as well as γ- and δ-lactones.

Palladium-Catalyzed trans-Hydroalkoxylation: Counterintuitive Use of an Aryl Iodide Additive to Promote C–H Bond Formation

We report an enantioselective palladium-catalyzed trans-hydroalkoxylation of propargylic amines with a trifluoroacetaldehyde-derived tether to build chiral oxazolidines. Diastereoselective hydrogenation using a heterogeneous palladium catalyst then gave access to protected benzylic amino alcohols in 45–87% yields and 84–94% ee values. Hydroalkoxylation of the alkynes required a catalytic amount of aryl iodide, highlighting the counterintuitive key role played by a putative Pd(II)/ArI oxidative addition complex to promote oxypalladation/protodemetalation.

Synthesis of syn- and enantioenriched anti-β-amino alcohols by highly diastereoselective borono-Mannich allylation reactions

A highly diastereoselective method for the synthesis of syn-β-amino alcohols and enantioenriched anti-β-amino alcohols has been developed involving α-hydroxyl aldehydes and chiral α-phenylaminoxyaldehydes or α-benzoyloxyaldehydes, respectively in Petasis borono-Mannich allylation reactions. This study broadens the scope and utility of the Petasis reaction to include pinacol allylboronate and highlights its unique reactivity and stereochemical outcomes.

Diastereoselective Three-Component 3,4-Amino Oxygenation of 1,3-Dienes Catalyzed by a Cationic Heptamethylindenyl Rhodium(III) Complex

The direct oxyamination of olefins is a compelling tool to rapidly access β-amino alcohols-a privileged motif ubiquitous in natural products, pharmaceuticals and agrochemicals. Although a variety of expedient methods are established for simple alkenes, selective amino oxygenation of 1,3-dienes is less explored. Within this context, methods for the oxyamination of 1,3-dienes that are selective for the internal position remain unprecedented. We herein report a modular three-component approach to perform an internal and highly diastereoselective amino oxygenation of 1,3-dienes catalyzed by a cationic heptamethylindenyl (Ind*) Rh(III) complex.

Chiral Hypervalent Iodine Catalysis Enables an Unusual Regiodivergent Intermolecular Olefin Aminooxygenation

A novel iodide-catalyzed intermolecular aminooxygenation strategy is described here. Amide is used as the O- and N- source to probe for regiocontrol strategies. Notably, simple additives can be selectively introduced to achieve regiodivergent oxyamination processes for electronically activated alkenes while being regio-complementary for unactivated alkenes. Our preliminary data demonstrates that this regiocontrol strategy based on nucleophile can also be applied in asymmetric processes using chiral hypervalent iodine catalysis.

Visible-Light-Induced Intermolecular Oxyimination of Alkenes

An intermolecular vicinal O-N difunctionalization reaction of olefins with oxime esters through energy transfer catalysis has been developed.

Heterocyclic group transfer reactions with I(iii) N-HVI reagents: access to N-alkyl(heteroaryl)onium salts via olefin aminolactonization

Pyridinium and related N-alkyl(heteroaryl)onium salts are versatile synthetic intermediates in organic chemistry, with applications ranging from ring functionalizations to provide diverse piperidine scaffolds to their recent emergence as radical precursors in deaminative cross couplings. Despite their ever-expanding applications, methods for their synthesis have seen little innovation, continuing to rely on a limited set of decades old transformations and a limited subset of coupling partners. Herein, we leverage (bis)cationic nitrogen-ligated I(iii) hypervalent iodine reagents, or N-HVIs, as "heterocyclic group transfer reagents" to provide access to a broad scope of N-alkyl(heteroaryl)onium salts via the aminolactonization of alkenoic acids, the first example of engaging an olefin to directly generate these salts. The reactions proceed in excellent yields, under mild conditions, and are capable of incorporating a broad scope of sterically and electronically diverse aromatic heterocycles. The N-HVI reagents can be generated in situ, the products isolated via simple trituration, and subsequent derivatizations demonstrate the power of this platform for diversity-oriented synthesis of 6-membered nitrogen heterocycles.

Aminolactonization of Unactivated Alkenes Catalyzed by Aryl Iodine

A one-step protocol of the aryl iodine-catalyzed aminolactonization of unactivated alkenes under oxidation conditions was first reported to efficiently construct diverse amino lactones in a short time using HNTs₂ as the compatible nitrogen source. In addition, we investigated the influence of the reaction rate based on the structure of the iodoarene precatalyst, which revealed the selective adjustment effect on aminolactonization and oxylactonization. Finally, preliminary experiments verified the feasibility of asymmetric aminolactonization catalyzed by a chiral iodoarene precatalyst.

Organoiodine-Catalyzed Enantioselective Intermolecular Oxyamination of Alkenes

Metal-free, catalytic enantioselective intermolecular oxyamination of alkenes is realized by use of organoiodine(I/III) chemistry. The protocol is applicable toward aryl- and alkyl-substituted alkenes with high enantioselectivity and electronically controlled regioselectivity. The oxyaminated products can be easily deprotected in one step to reveal free amino alcohols in high yields without loss of enantioselectivity. A key to our success is the discovery of a virtually unexplored chemical entity, N-(fluorosulfonyl)carbamate, as a bifunctional N,O-nucleophile.

Beyond osmium: progress in 1,2-amino oxygenation of alkenes, 1,3-dienes, alkynes, and allenes

Olefin 1,2-difunctionalization has emerged as a popular strategy within modern synthetic chemistry for the synthesis of vicinal amino alcohols and derivatives. The advantage of this approach is the single-step simplicity for rapid diversification, feedstock nature of the olefin starting materials, and the possible modularity of the components. Although there is a vast number of possible iterations of 1,2-olefin difunctionalization, 1,2-amino oxygenation is of particular interest due to the prevalence of both oxygen and nitrogen within pharmaceuticals, natural products, agrochemicals, and synthetic ligands. The Sharpless amino hydroxylation provided seminal results in this field and displayed the value in achieving methods of this nature. However, a vast number of new and novel methods have emerged in recent decades. This review provides a comprehensive review of modern advances in accomplishing 1,2-amino oxygenation of alkenes, 1,3-dienes, alkynes, and allenes that move beyond osmium to a range of other transition metals and more modern strategies such as electrochemical, photochemical, and biochemical reactivity.

Ru-Tethered (R,R)-TsDPEN with DMAB as an efficient catalytic system for high enantioselective one-pot synthesis of chiral β-aminol via asymmetric transfer hydrogenation

This work reflects Ru-tethered-TsDPEN as an active chiral catalyst for one pot selective synthesis of optically active α-substituted alcohols and its derivatives from α-bromo ketones in the presence of dimethylamine borane (DMAB) as the hydrogen source.

Iodoarene-Catalyzed Oxyamination of Unactivated Alkenes to Synthesize 5-Imino-2-Tetrahydrofuranyl Methanamine Derivatives

Reported here is the room-temperature metal-free iodoarene-catalyzed oxyamination of unactivated alkenes. In this process, the alkenes are difunctionalized by the oxygen atom of the amide group and the nitrogen in an exogenous HNTs₂ molecule. This mild and open-air reaction provided an efficient synthesis to N-bistosyl-substituted 5-imino-2-tetrahydrofuranyl methanamine derivatives, which are important motifs in drug development and biological studies. Mechanistic study based on experiments and density functional theory calculations showed that this transformation proceeds via activation of the substrate alkene by an in situ generated cationic iodonium(III) intermediate, which is subsequently attacked by an oxygen atom (instead of nitrogen) of amides to form a five-membered ring intermediate. Finally, this intermediate undergoes an S_N2 reaction by NTs₂ as the nucleophile to give the oxygen and nitrogen difunctionalized 5-imino-2-tetrahydrofuranyl methanamine product. An asymmetric variant of the present alkene oxyamination using chiral iodoarenes as catalysts also gave promising results for some of the substrates.

SLAP reagents for the photocatalytic synthesis of C3/C5-substituted, N-unprotected selenomorpholines and 1,4-selenazepanes

Herein, we disclose the first set of unique selenium-containing SLAP (SiLicon Amine Protocol) reagents for the direct synthesis of C3/C5-substituted selenomorpholines and 1,4-selenazepanes from diverse (hetero)aldehydes under mild photocatalytic conditions. Enantiomerically pure 1,2-amino alcohol/α-amino acid versions of these heterocycles were also synthesized. Further, we have shown the late-stage modification of certain biologically active agents using the developed seleno-SLAP reagents.

Enantioselective Carboetherification/Hydrogenation for the Synthesis of Amino Alcohols via a Catalytically Formed Chiral Auxiliary

Chiral auxiliaries and asymmetric catalysis are the workhorses of enantioselective transformations, but they still remain limited in terms of either efficiency or generality. Herein, we present an alternative strategy for controlling the stereoselectivity of chemical reactions. Asymmetric catalysis is used to install a transient chiral auxiliary starting from achiral precursors, which then directs diastereoselective reactions. We apply this strategy to a palladium-catalyzed carboetherification/hydrogenation sequence on propargylic amines, providing fast access to enantioenriched chiral amino alcohols, important building blocks for medicinal chemistry and drug discovery. All stereoisomers of the product could be accessed by the choice of ligand and substituent on the propargylic amine, leading to a stereodivergent process.

Rhodium-catalyzed iminoiodane-mediated oxyamidation studies of 5-vinyluracil derivatives using aryl and alkyl sulfamates

The dirhodium tetraacetate-catalyzed iminoiodane-mediated reaction of 1,3-dimethyl-5-vinyluracil with phenyl sulfamate provided a high yield of 5-(1-acetyl-2-phenylsulfamoyl)ethyluracil via regioselective nucleophilic ring opening by acetate anion of the transiently formed 5-(1,2)-N-phenylsulfonylaziridine intermediate. This 1,2-oxyamidation reaction was found to be general for a variety of aryl- and alkylsulfamates as well as for various 1,3-dialkyl-5-vinyluracil derivatives. Addition of an alcohol to the reaction mixture allowed formation of the corresponding 1-alkoxy products. A selection of the substituted uracil derivatives prepared by this procedure was evaluated for cytotoxic activities in HCT-116 and HepG2 cancer cell lines and showed either no or modest activities. Further evaluation for α-glucosidase inhibition revealed that compounds 15ca and 15da were more active than acarbose, the reference inhibitor. This methodology thus allows efficient preparation of highly functionalized uracil derivatives thereby providing a synthetic route to novel compounds with potentially useful biological activities.