3219-55-4

A rhodium(III)-catalyzed aerobic oxidative cross-coupling of acrylamides with unactivated alkenes via vinylic C-H activation has been developed. The present cross-coupling reaction was examined with a variety of differently functionalized acrylamides and unactivated olefins. In these reactions, highly valuable amide-functionalized butadienes were prepared in good to excellent yields. This protocol was also compatible with Weinreb amides. A possible reaction mechanism involving the chelation-assisted vinylic C-H activation via a carboxylate-assisted deprotonation pathway is proposed.

A novel chemodivergent cross-coupling of acrylamides and vinyl acetates has been realized via metal-catalyzed vinylic C-H activation. The selective olefinic C-H vinylation and alkenylation reaction was examined with a variety of differently functionalized acrylamides. The reaction efficiently generates a range of highly synthetically valuable butadienes with good functional group tolerance in good to moderate yields. A possible catalytic reaction mechanism involving the chelation-assisted olefinic C-H activation via an acetate-assisted deprotonation pathway is proposed.

Isoselenazolone derivatives have attracted significant research interest because of their potent therapeutic activities and indispensable applications in organic synthesis. Efficient construction of functionalized isoselenazolone scaffolds is still challenging, and thus new synthetic approaches with improved operational simplicity have been of particular interest. In this manuscript, we introduce a rhodium-catalyzed direct selenium annulation by using stable and tractable elemental selenium. A series of benzamides as well as acrylamides were successfully coupled with selenium under mild reaction conditions, and the obtained isoselenazolones could be pivotal synthetic precursors for several organoselenium compounds. Based on the designed control experiments and X-ray absorption spectroscopy measurements, we propose an unprecedented selenation mechanism involving a highly electrophilic Se(IV) species as the reactive selenium donor. The reaction mechanism was further verified by a computational study.

Targeted covalent inhibitors are an important class of drugs and chemical probes. However, relatively few electrophiles meet the criteria for successful covalent inhibitor design. Here we describe α-substituted methacrylamides as a new class of electrophiles suitable for targeted covalent inhibitors. While typically α-substitutions inactivate acrylamides, we show that hetero α-substituted methacrylamides have higher thiol reactivity and undergo a conjugated addition-elimination reaction ultimately releasing the substituent. Their reactivity toward thiols is tunable and correlates with the pKa/pKb of the leaving group. In the context of the BTK inhibitor ibrutinib, these electrophiles showed lower intrinsic thiol reactivity than the unsubstituted ibrutinib acrylamide. This translated to comparable potency in protein labeling, in vitro kinase assays, and functional cellular assays, with improved selectivity. The conjugate addition-elimination reaction upon covalent binding to their target cysteine allows functionalizing α-substituted methacrylamides as turn-on probes. To demonstrate this, we prepared covalent ligand directed release (CoLDR) turn-on fluorescent probes for BTK, EGFR, and K-RasG12C. We further demonstrate a BTK CoLDR chemiluminescent probe that enabled a high-throughput screen for BTK inhibitors. Altogether we show that α-substituted methacrylamides represent a new and versatile addition to the toolbox of targeted covalent inhibitor design.

The first cobalt-catalyzed cross-couplings between olefins has been demonstrated to provide C(alkenyl)-H alkenylation and alkylation products, using complex [Cp?Co(CO)I2]. While coupling partner acrylates afforded conjugated dienoates, α,β-unsaturated ketones led to γ-alkenyl ketones completely, representing a switchable C-H functionalization controlled by different carbonyl groups.

Mechanistic insights into trithiocarbonate degradation during the RAFT polymerization of N-arylmethacrylamides are reported. Previous work by our group showed significant RAFT agent degradation during the polymerization of N-arylmethacryloyl sulfonamides at 70 °C. Herein we report the influence of methacrylamide structure on trithiocarbonate degradation during the RAFT polymerizations of N-phenylmethacrylamide (PhMA) and N-benzylmethacrylamide (BnMA) in DMF at 70 and 30 °C. UV-vis spectroscopy revealed trithiocarbonate degradation occurs exclusively after covalent addition of monomer to the RAFT agent, with 60% trithiocarbonate degradation occurring after 12 h during the polymerization of PhMA at 70 °C compared to only 3% degradation measured during the polymerization of BnMA under identical conditions. Small molecule analogues of trithiocarbonate-functional poly(PhMA) and poly(BnMA) were synthesized by single monomer unit insertion and the kinetics and byproducts of degradation investigated by in situ 1H NMR analysis at 70 °C. Trithiocarbonate degradation was ultimately shown to occur by N-phenyl-promoted, N-5 nucleophilic attack on the terminal thiocarbonyl by the ultimate methacrylamide unit.

An oxy-palladation, formal Wagner-Meerwein rearrangement and fluorination cascade has been established for generating fluorinated oxazolidine-2,4-diones and oxazolidin-2-ones. The reaction has a broad substrate scope in which both aryl and alkyl groups can be utilized as efficient migrating groups. Experimental evidence suggests that the reaction is initiated by anti-oxy-palladation of the olefin, followed by oxidative generation of an alkyl PdIV intermediate and a concerted migration-fluorination.

Chemoselective synthesis of N-protected β-amino esters involving lipase-catalyzed aza-Michael additions and α,β-unsaturated precursors is mainly hampered by the two electrophilic sites present on these compounds. In order to control the chemoselectivity a solvent engineering strategy based on the thermodynamic behaviour of products in media of different polarity was designed. This strategy allowed to obtain aza-Michael adducts from benzylamine and different acrylates with high selectivity. In almost all reactions carried out in n-hexane, a non-polar solvent, aminolysis was avoided while the corresponding Michael adducts were exclusively synthesized in 53-78% yields. On the contrary, in reactions carried out in a polar solvent such as 2-methyl-2-butanol the aminolysis products were favoured. Thermodynamic analyses of these processes using the COSMO-RS method helped to understand some of the key factors affecting chemoselectivity and confirmed that a reliable estimation of the thermodynamic interactions of solutes and solvents allows an adequate selection of a reaction media that may lead to chemoselectivity.

Various substituted homotaurines (=3-aminopropane-1-sulfonic acids) 6 were readily synthesized in satisfactory to good yields via the Michael addition of thioacetic acid to alk-2-enamides 3 (→4), followed by LiAlH4 reduction (→5) and performic acid oxidation (Scheme 1). The configuration of 'anti'-disubstituted homotaurine 'anti'-6h was deduced from the 3-(acetylthio)alkanamide (=S-(3-amino-1,2-dimethyl-3-oxopropyl) ethanethioate)'anti'-4h formed in the Michael addition, which was identified via the Karplus equation analysis, and confirmed by X-ray diffraction analysis. The current route is an efficient method to synthesize diverse substituted homotaurines, including 1-, 2-, and N-monosubstituted, as well as 1,2-, 1,N-, 2,N-, and N,N-disubstituted homotaurines (Table). Copyright

Reported herein is the development of the Ir(III)-catalyzed direct C-H amidation of arenes and alkenes using acyl azides as the nitrogen source. This procedure utilizes an in situ generated cationic half-sandwich iridium complex as a catalyst. The reaction takes place under very mild conditions, and a broad range of sp2 C-H bonds of chelate group-containing arenes and olefins are smoothly amidated with acyl azides without the intervention of the Curtius rearrangement. Significantly, a wide range of reactants of aryl-, aliphatic-, and olefinic acyl azides were all efficiently amidated with high functional group tolerance. Using the developed approach, Z-enamides were readily accessed with a complete control of regio- and stereoselectivity. The developed direct amidation proceeds in the absence of external oxidants and releases molecular nitrogen as a single byproduct, thus offering an environmentally benign process with wide potential applications in organic synthesis and medicinal chemistry.

A methodology has been developed for an efficient and selective lipase-catalyzed aza-Michael reaction of various amines (primary and secondary) with a series of acrylates and alkylacrylates. Reaction parameters were tuned, and under the optimal conditions it was found that Pseudomonas stutzeri lipase and Chromobacterium viscosum lipase showed the highest selectivity for the aza-Michael addition to substituted alkyl acrylates. For the first time also, some CLEAs were examined that showed a comparable or higher selectivity and yield than the free enzymes and other formulations.

Ruthenium- and rhodium-catalyzed direct oxidative cross-coupling reactions of acrylamides with alkenes were developed. These methods provide an efficient route for the synthesis of (Z,E)-dienamides in excellent yields with good stereoselectivity. The catalytic systems allowed oxidative olefination of a wide range of alkenes bearing different functional groups, such as CO2R, COMe, SO2Ph, aryl, CONHBn, CN, PO(OEt)2, as well as Weinreb amide.

It has been repor ted that the length of the molecular chain and the rigidity of molecules influence the structure of the polymer network in PDLC films and hence the electro-optical proper ties of the composites. Herein, a series of new aromatic monomeric monomethacrylates, bismethacrylates and monovinylbenzene derivatives with a mesogenic core were successfully synthesized under microwave irradiation. The microwave assisted synthesis resulted in decreased reaction times, reduced solvent requirement, increased operational simplicity, and in most cases, improved yields and selectivity. Versita Sp. z o.o.

Silver oxide used in stoichiometric amounts promoted the direct functionalization of tert-alkyl bromides and provided the desired adducts in 39-96% isolated yield. Reaction of tert-bromides with carboxylic acids yielded esters, with alcohols and phenols yielded alkyl and aryl ethers, with amines and anilines yielded selectively mono-alkylated amines and anilines, and with a C-nucleophile yielded an all-carbon quaternary hydrocarbon. The method was applied to a sequential alkylation of a primary amine with two different alkyl bromides yielding selectively a tertiary amine with three different substituents in one-pot.

The radical reactions of N-(2-halogenoalkanoyl)-substituted anilines (anilides) of type 1 have been investigated under various conditions. Treatment of compounds 1a-1o with Bu3SnH in the presence of (2,2′-azobis(isobutyronitrile) (AIBN) afforded a mixture of the indolones (oxindoles) 2a-2o and the reduction products 5a-5o (Table 1). In contrast, the N-unsubstituted anilides 1p-1s, 1u, and 1v gave the corresponding reduction products exclusively (Table 1). Similar results were obtained by treatment of 1 with Ni powder (Table 2) or wth Et3B (Table 3). Anilides with longer N-(phenylalkyl) chains such as 6 and 7 were inert towards radical cyclization, with the exception of N-benzyl-2-bromo-N,2-dimethylpropanamide (6b), which, upon treatment with Ni powder in i-PrOH, afforded the cyclized product 9b in low yield (Table 4). Upon irradiation, the extended anilides 6, 7, 10, and 11 yielded the corresponding dehydrobromination products exclusively (Table 5).

Hydridopalladium(II) species generated in situ by oxidative addition of Pd(0) to acetic acid or acidic hydroxyl substrates (phenols, oximes) catalyse the termolecular assembly of allenes, CO and amines (primary, secondary) or oxygen nucleophiles to give methacrylamides or methacrylate esters and derivatives thereof in good to excellent yield.

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Electrogenerated bases promote the carboxylation of NH-protic carboxamides bearing a leaving group at the position 2 to give oxazolidine-2,4-diones.The process is believed to involve acid-base reaction with the substrate, carboxylation of its conjugate base to corresponding carbamate and ring-closure following intramolecular SN2 reaction.A variety of oxazolidine-2,4-diones, including clinically used trimethadione and malidone, have been prepared in high to excellent yield, which established the scope and generality of this new ring-forming process.

Silver oxide promotes substitution of the bromine at position 2 of α- bromocarboxamides, with a hydroxyl or an alkoxyl group.

Candida cylindracea lipase is a useful catalyst for the preparation of propiolamides. Candida antarctica lipase efficiently catalyzes the aminolysis of different acrylic esters and aliphatic amines; if racemic amines are used, the corresponding optically active acrylic amide is obtained in moderate-high enantiomeric excess.

N-Substituted 2,3-dibromo-2-alkylacrylamides obtained by the bromination of 2-alkylacrylamides were converted to 1,3-disubstituted 3-bromo-2-azetidinones in excellent yields upon treatment with potassium carbonate in acetone under refluxing.

Glycoylamides were obtained in high yields in the presence of silver oxide at room temperature from 2-bromoisobutyramides and the partially protected monosaccharides, 1,2:3,4-di-O-isopropylidene-D-galactopyranose, 5, 1,2:5,6-di-O-isopropylidene-D-glucofuranose, 6, and 2,3,4,6-tetra-O-benzyl-D-glucopyranose, 7.Full characterization through 1H and 13C NMR spectra has been achieved.

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The base-promoted reaction of 2-bromo-2-methylpropanamides (1) with 5-, 6-, and 7-membered lactams (2) affords spiro-oxazolidinones (3).The latter compounds are hydrolysed under acidic conditions to yield the ω-aminoester amides (7).The solvolytic behaviour of some monocyclic oxazolidinones obtained upon reaction of common amides with 2-bromoamides (1) is also reported.

The electrochemical reduction of series of secondary and tertiary α-bromoisobutyramides has been studied in dipolar aprotic solvents.A carbanion is formed at the mercury electrode as a consequence of two-electron C-Br bond cleavage.Voltammetry and macroelectrolysis point to a self-protonation mechanism, the carbanion undergoing protonation by a parent molecule to yield the isobutyramide.Concurrently, tertiary 2-bromoamides undergo 1,2-elimination to yield an αβ-unsaturated amide, while secondary 2-bromoamides are deprotonated at the nitrogen atom, affording a bromo-containing anion.The decay of the latter is strongly dependent on the solvent and the substituent at nitrogen.In acetonitrile, elimination and fragmentation products are identified in the electrolysed solution.On the other hand, in N,N-dimethylformamide or N,N-dimethylacetamide, the bromo-containing anion is eventually cyclocondensed onto the carbonyl group of the amide solvent, to yield an oxazolidin-4-one derivative.Preliminary data suggest that an analogous cyclocoupling reaction takes place when the reduction is carried out in 1-methyl-2-pyrrolidone.

Electrochemical reduction of 2-bromo-carboxamides involves self-protonation of the electrogenerated bases and affords, among other products, cyclo-adducts incorporating a dimethylformamide unit.

A process is described for producing N-substituted acrylamide or methacrylamide comprising reacting an acrylic or methacrylic acid ester with an aliphatic or aromatic amine in liquid medium in the presence of a catalytic amount of alkyltin alkoxide.