Allylic Amides Research Articles

Enantioselective and Regiodivergent Copper-Catalyzed Electrophilic Arylation of Allylic Amides with Diaryliodonium Salts.

A catalytic enantioselective and regiodivergent arylation of alkenes is described. Chiral copper(II)bisoxazoline complexes catalyze the addition of diaryliodonium salts to allylic amides in excellent ee. Moreover, the arylation can be controlled by the electronic nature of the diaryliodonium salt enabling the preparation of nonracemic diaryloxazines or β,β′-diaryl enamides.

Enantioselective bromocyclization of allylic amides catalyzed by BINAP derivatives.

A highly enantioselective bromocyclization of allylic amides with N-bromosuccinimide (NBS) was developed with DTBM-BINAP as a catalyst, affording chiral oxazolines with a tetrasubstituted carbon center in high yield with up to 99% ee. By utilizing the bromo substituent as a handle, the obtained compounds were converted to synthetically useful chiral building blocks.

ChemInform Abstract: Catalytic Enantioselective Amide Allylation of Isatins and Its Application in the Synthesis of 2‐Oxindole Derivatives Spiro‐Fused to the α‐Methylene‐γ‐Butyrolactone Functionality.

This article is a full account of the work exploring the potential utility of catalytic enantioselective amide allylation of various isatins using indium-based chiral catalysts. A survey of various isatin substrates and NH-containing stannylated reagents revealed that the reaction has a remarkably wide scope to result in extremely high yields and enantioselectivities (up to >99 %, 99 % ee) of variously substituted homoallylic alcohols. Several mechanistic investigations demonstrated that the substrate-reagent hydrogen-bond interaction plays a critical role in the formation of the key transition states to result in enhanced catalytic reaction. The success of this approach allowed convenient access to chiral 2-oxindoles spiro-fused to the α-methylene-γ-butyrolactone functionality and their halogenated derivatives in almost enantiopure forms, thus highlighting the general utility of this synthetic method to deliver a large variety of antineoplastic drug candidates and pharmaceutically meaningful compounds.

Divergent Regioselectivity in Photoredox-Catalyzed Hydrofunctionalization Reactions of Unsaturated Amides and Thioamides.

A direct method to construct 2-oxazolines and 2-thiazolines from corresponding allylic amides and thioamides is reported. The redox-neutral intramolecular hydrofunctionalization is enabled by a dual catalyst system comprised of the 9-mesityl-N-methyl acridinium tetrafluoroborate and phenyl disulphide and exhibits complete selectivity for the anti-Markovnikov regioisomeric products. The cyclization of allylic thioamides is postulated to operate via a modified mechanism in which oxidation of the thioamide, rather than the alkene, is responsible for the observed reactivity.

BF3-Et2O mediated skeletal rearrangements of norbornyl appended cyclopentanediols.

An unusual cascade rearrangement has been noticed as a competitive reaction during the treatment of norbornyl appended cyclopentanediols with a Lewis acid (LA): a BF3-Et2O mediated pinacol-pinacolone rearrangement. Deketalization and pinacolone rearrangement occur at two different sites in the molecule and are responsible for the observed cascade rearrangement product. However, deketalization appears to be triggering the cascade steps. The kinetically more stable pinacolone product with an exo-Me group was observed in the case of the bromo analogue, whereas, the thermodynamically more stable pinacolone product with an endo-Me group was observed in the case of the chloro analogue. Epimerization via tautomerization of one diastereomer to the other diastereomer under Lewis acid reflux conditions is possible. On the contrary, the diol equivalent epoxides provide only the diastereomeric mixture of pinacolone products under similar LA reaction conditions. The lower yields observed in the case of the epoxides are due to unwanted side reactions taking place between the two competitive reactive centers, namely, ketal and epoxide. Further, a sequence of elimination, nucleophilic substitution and Ritter type hydrolysis reactions of the epoxides resulted in unexpected elimination products. This transformation not only facilitates a regioselective epoxide opening, but also provides a new route for the preparation of allylic amides of the norbornyl appended cyclopentane ring system.

ChemInform Abstract: Catalytic Amide Allylation of α‐Ketoesters: Extremely High Enantioselective Synthesis of Ester Functionalized α‐Methylene‐γ‐butyrolactones.

AbstractThe previously reported carbonyl allylation of isatin derivatives with β‐amido‐functionalized allylstannanes is extended towards the challenging utilization of α‐ketoesters as acyclic 1,2‐dicarbonyl substrates.

СИНТЕЗ НОВЫХ БИОЛОГИЧЕСКИ АКТИВНЫХ ПОЛИМЕРНЫХ БИОКОНЪЮГАТОВ НА ОСНОВЕ ЛУПАНОВЫХ АЛЛИЛАМИДОВ

The work is devoted to the synthesis of new copolymers based on allylamides of betulonic and 2 hydroximinobetulonic acids and study of their cytotoxic activity. Allylamides of betulonic and 2 hydroximinobetulonic acids were prepared by the reaction of corresponding acids with allylamine in the presence of oxalyl chloride and triethylamine. It was established that the allylamides obtained do not homopolymerize, but copolymerize with low rates with acrylonitrile and N-vinylpyrrolidone in the presence of radical initiators The investigations of radical copolymerization of allylamides with acrylonitrile and N-vinyl­pyrrolidone showed that the resulting copolymers have a statistical distribution of the comonomer units in the macromolecule, wherein in the entire range of monomer concentrations the copolymers are enriched by the vinyl monomer units. The copolymerization rates are considerably reduced by increasing the content of allylamides in the initial monomer mixture in all copolymerization systems, the copolymerization rate of allylamide with acrylonitrile is higher than with N-vinylpyrrolidone. At the copolymerization in bulk with enhancing degree of conversion there is a gel-effect, which is associated with an increasing of the viscosity in the absence of solvent; at the copolymerization in solution gel-effect is absent. The structure of the copolymers obtained was determined by 1 H NMR spectroscopy. It was established that the products obtained are a mixture of copolymers of allyl amides and oligomers thereof. In the spectra of the reaction products a number of additions of the vinyl monomer with the participating of double bond of isopropylidene group is also observed. The copolymers obtained have a cytotoxic activity: the copolymer of allylamide of betulonic acid with N-vinylpyrrolidone exhibits 4-fold higher activity against MS culture when compared with the initial ally amide and is promising for developing new bioactive polymer bioconjugates.

Palladium-Catalyzed Anti-Markovnikov Oxidation of Allylic Amides to Protected β-Amino Aldehydes.

A general method for the preparation of N-protected β-amino aldehydes from allylic amines or linear allylic alcohols is described. Here the Pd(II)-catalyzed oxidation of N-protected allylic amines with benzoquinone is achieved in tBuOH under ambient conditions with excellent selectivity toward the anti-Markovnikov aldehyde products and full retention of configuration at the allylic carbon. The method shows a wide substrate scope and is tolerant of a range of protecting groups. Furthermore, β-amino aldehydes can be obtained directly from protected allylic alcohols via palladium-catalyzed autotandem reactions, and the application of this method to the synthesis of β-peptide aldehydes is described. From a mechanistic perspective, we demonstrate that tBuOH acts as a nucleophile in the reaction and that the initially formed tert-butyl ether undergoes spontaneous loss of isobutene to yield the aldehyde product. Furthermore, tBuOH can be used stoichiometrically, thereby broadening the solvent scope of the reaction. Primary and secondary alcohols do not undergo elimination, allowing the isolation of acetals, which subsequently can be hydrolyzed to their corresponding aldehyde products.

ChemInform Abstract: Enantioselective Synthesis of 1‐Vinyltetrahydroisoquinolines Through Palladium‐Catalyzed Intramolecular Allylic Amidation with Chiral PhthalaPhos Ligands.

AbstractIt is demonstrated that (S)‐BINOL based PhthalaPhos ligands can be used as catalyst for the intramolecular asymmetric allylic amidation of achiral aminocarbamates such as (I) and (III).

Reduction of N-allylamides by LiAlH4: unexpected attack of the double bond with mechanistic studies of product and byproduct formation.

The reduction of secondary allyl amides with LiAlH4 can lead to a concomitant reduction of the double bond. Previously, an excess of LiAlH4 in hazardous solvents was used for the reduction. This work discusses optimized reaction conditions in tBuOMe as a safe solvent, with only a 1.5-fold excess of LiAlH4, without reduction of the double bond in most cases. (1)H and (2)D NMR spectroscopic studies give evidence for the mechanism of the reduction of the amide as well as the double bond: Amide reduction generally precedes double bond reduction. Sterically hindered allylamides are an exception. They are reduced considerably more slowly at higher temperatures, and double bond reduction is observed before amide reduction has gone to completion.

Catalytic amide allylation of α-ketoesters: extremely high enantioselective synthesis of ester functionalised α-methylene-γ-butyrolactones.

This communication reports a significant breakthrough on the novel catalytic amide allylation to the acyclic α-ketoester systems, achieving satisfactorily high yields and extremely high levels of the asymmetric induction to allow for highly enantioselective synthesis of ester functionalised α-methylene-γ-butyrolactones.

Catalytic enantioselective amide allylation of isatins and its application in the synthesis of 2-oxindole derivatives spiro-fused to the α-methylene-γ-butyrolactone functionality.

This article is a full account of the work exploring the potential utility of catalytic enantioselective amide allylation of various isatins using indium-based chiral catalysts. A survey of various isatin substrates and NH-containing stannylated reagents revealed that the reaction has a remarkably wide scope to result in extremely high yields and enantioselectivities (up to >99 %, 99 % ee) of variously substituted homoallylic alcohols. Several mechanistic investigations demonstrated that the substrate-reagent hydrogen-bond interaction plays a critical role in the formation of the key transition states to result in enhanced catalytic reaction. The success of this approach allowed convenient access to chiral 2-oxindoles spiro-fused to the α-methylene-γ-butyrolactone functionality and their halogenated derivatives in almost enantiopure forms, thus highlighting the general utility of this synthetic method to deliver a large variety of antineoplastic drug candidates and pharmaceutically meaningful compounds.

Asymmetric synthesis of N,O-heterocycles via enantioselective iridium-catalysed intramolecular allylic amidation

Chiral N,O-heterocycles were synthesized in high yields and excellent enantioselectivity up to 97% ee via iridium-catalysed intramolecular allylic substitution with nucleophilic attack by the amide oxygen atom. The resulting benzoxazine derivatives were further transformed into challenging chiral N,O-ketals bearing both a tertiary and a quaternary center with excellent diastereoselectivities.

ChemInform Abstract: Construction of Spiro‐Fused 2‐Oxindole/α‐Methylene‐ γ‐butyrolactone Systems with Extremely High Enantioselectivity via Indium‐Catalyzed Amide Allylation of N‐Methyl Isatin.

A remarkably effective method allowing an extremely high enantioselective synthesis of the spiro-fused 2-oxindole/α-methylene-γ-butyrolactones is described. The key strategy lies in the use of indium-catalyzed asymmetric amide allylation of N-methyl isatin with functionalized allylstannanes, which can lead to the antineoplastic spirocyclic lactones in almost enantiopure forms.

Enantioselective synthesis of 1-vinyltetrahydroisoquinolines through palladium-catalysed intramolecular allylic amidation with chiral PhthalaPhos ligands

The PhthalaPhos ligands, chiral BINOL monophosphites endowed with a phthalamide group, have been screened in the synthesis of 1-vinyltetrahydroisoquinolines by intramolecular palladium-catalysed asymmetric allylic amidation (AAA) of achiral tosylamidocarbonates. Identification of the best ligand followed by optimisation of the reaction conditions allowed the desired product to be obtained with up to 83% ee. Remarkably, the reaction is stereoconvergent, affording the same enantiomer of the desired product regardless of the geometry of the allylic carbonate’s double bond, which allows, in principle, the use of E/Z mixtures.

Palladium‐Catalyzed Stereoselective Intramolecular Oxidative Amidation of Alkenes in the Synthesis of 1,3‐ and 1,4‐Amino Alcohols and 1,3‐Diamines

An efficient and practical Pd-catalyzed intramolecular oxidative allylic amidation provides facile access to derivatives of 1,3- and 1,4-amino alcohols and 1,3-diamines. The method operates under mild reaction conditions (RT) with molecular oxygen (1 atm) as the sole reoxidant of Pd. Excellent diastereoselectivities were attained with substrates bearing a secondary stereogenic center.

ChemInform Abstract: Multifaceted Catalysis Approach to Nitrile Activation: Direct Synthesis of Halogenated Allyl Amides from Allylic Alcohols.

AbstractTitle compounds (III) and (V) are synthesized from the reaction of allylic alcohols (I) and halogenated nitriles (II) and (IV), respectively.

A General Catalytic Hydroamidation of 1,3‐Dienes: Atom‐Efficient Synthesis of N‐Allyl Heterocycles, Amides, and Sulfonamides

AbstractTransition‐metal‐catalyzed hydroamination reactions are sustainable and atom‐economical CN bond‐forming processes. Although remarkable progress has been made in the inter‐ and intramolecular amination of olefins and 1,3‐dienes, related intermolecular reactions of amides are still much less known. Control of the regioselectivity without analogous telomerization is the particular challenge in the catalytic hydroamidation of alkenes and 1,3‐dienes. Herein, we report a general protocol for the hydroamidation of electron‐deficient N‐heterocyclic amides and sulfonamides with 1,3‐dienes and vinyl pyridines in the presence of a catalyst derived from [{Pd(π‐cinnamyl)Cl}2] and ligand L7 or L10. The reactions proceeded in good to excellent yield with high regioselectivity. The practical utility of our method is demonstrated by the hydroamidation of functionalized biologically active substrates. The high regioselectivity for linear amide products makes the procedure useful for the synthesis of a variety of allylic amides.

A General Catalytic Hydroamidation of 1,3‐Dienes: Atom‐Efficient Synthesis of N‐Allyl Heterocycles, Amides, and Sulfonamides

Transition-metal-catalyzed hydroamination reactions are sustainable and atom-economical CN bond-forming processes. Although remarkable progress has been made in the inter- and intramolecular amination of olefins and 1,3-dienes, related intermolecular reactions of amides are still much less known. Control of the regioselectivity without analogous telomerization is the particular challenge in the catalytic hydroamidation of alkenes and 1,3-dienes. Herein, we report a general protocol for the hydroamidation of electron-deficient N-heterocyclic amides and sulfonamides with 1,3-dienes and vinyl pyridines in the presence of a catalyst derived from [{Pd(π-cinnamyl)Cl}2 ] and ligand L7 or L10. The reactions proceeded in good to excellent yield with high regioselectivity. The practical utility of our method is demonstrated by the hydroamidation of functionalized biologically active substrates. The high regioselectivity for linear amide products makes the procedure useful for the synthesis of a variety of allylic amides.

Synthesis of α‐Amino‐γ‐lactams through Pd‐Catalzed Intramolecular Allylic Alkylation of Sarcosine Allyl Amides

AbstractN‐Protected amino acid allyl amides with an allylic leaving group can be used as substrates in palladium‐catalyzed allylic alkylation. Whereas intermolecular allylations proceed with excellent yields under standard conditions for enolate reactions, the intramolecular version is not a trivial issue. N‐Protected glycine amides preferentially form piperidinones through N‐allylation, but the corresponding sarcosine derivatives provide γ‐lactams in acceptable to good yields in dichloromethane, especially when the corresponding titanium enolates are formed.