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Search for "amide" in Full Text gives 973 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts
Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243
- -arylation of N-alkoxybenzamides 81 in absence of metal catalsyt at low temperatures [85]. The reaction resulted in the two products O-arylated 83 and N-arylated 84 amides (Scheme 33). By reacting various substituted diaryliodonium salts and the amide it was concluded that the chemoselectivity between O- and
- N-arylation could be controlled by adjusting the steric and/or electronic properties of the diaryliodonium salt and the amide. This approach was helpful in the formation of O-arylimidates previously unattainable using metal-catalyzed methods. S-Arylation The aryl sulfide moiety is widely present in
N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity
Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240
- trichloroacetimidate failed, due to competing formation of orthoester-like amide acetals during the reaction with 1b. We then focused our work on an alternative synthetic approach (vide infra). In 2021, Pfretzschner and Unverzagt reported the application of our methodology to the synthesis of indigo-N-glucoside 7c
- (Scheme 4) [20]. The reaction of 1b with 3,4,6-tri-O-acetyl-2-O-benzoyl-α-ᴅ-glucosyl trichloroacetimidate (6a) afforded indigo-N-glycoside 7a. The benzoyl group located at OH-2 seemed to be unreactive enough to avoid formation of orthoester-like amide acetals during the N-glycosylation with 1b. Oxidative
- -mannose (14) afforded indigo-N-mannoside α-15a, albeit, in low yield (Scheme 11) [21]. Deacetylation afforded product α-15b. Indirubin-N-glycosides (red sugars) In contrast to indigo, indirubin is a non-symmetrical compound containing an amine- and an amide-type nitrogen atom. In our group, we developed a
Synthesis of tricarbonylated propargylamine and conversion to 2,5-disubstituted oxazole-4-carboxylates
Beilstein J. Org. Chem. 2024, 20, 2827–2833, doi:10.3762/bjoc.20.238
- reacts with butyllithium, ring closure occurs between the ethynyl and carbamoyl groups, yielding 2,5-disubstituted oxazole-4-carboxylates. This cyclization also occurs when the propargylamine is heated with ammonium acetate, resulting in double activation. Keywords: acid amide; diethyl mesoxalate; N
- anhydride, the intermediately formed hemiacetal underwent acetylation, leading to N,O-acetals 1. In this method, an acid amide can be used as an amine masked with an acyl group. Subsequent elimination of acetic acid occurred to afford 2 in situ upon treatment with a base, enabling nucleophilic addition with
- various nucleophiles. This is because the imino carbon atom of 2 is also highly electrophilic, similar to DEMO [23][24][25]. This method offers an advantage over conventional methods as the N-acyl group can be modified by altering the acid amide. In this study, lithium acetylides were employed as
Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines
Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236
- spectra of the imidazopyrimidine 4d there are cross peaks of the methine proton at C-5 with the amide proton of the acetamide fragment (Figure 3), which are not possible in the case of the hypothetical imidazoimidazoles 10 and 12. Also the observed cross peak of the same methine proton with the proton at
- C-3 of the imidazole core, would not be possible for the alternative imidazopyrimidine system. These results allowed us to reject the structure 11. The lack of correlation in the HMBC spectra between the protons of the amide fragment and the C-5 carbon atom, as well as the presence of cross-peaks of
Access to optically active tetrafluoroethylenated amines based on [1,3]-proton shift reaction
Beilstein J. Org. Chem. 2024, 20, 2776–2783, doi:10.3762/bjoc.20.233
- amide (S)-23b in 27% isolated yield over three-steps. The measurement of HPLC equipped with a chiral column, CHIRALPAK AD-H for (S)-23b, showed that the amide had an optical purity of 95% ee (Scheme 4). On the next stage, the substrate scope for the present reaction was explored by using various imines
Synthesis of fluoroalkenes and fluoroenynes via cross-coupling reactions using novel multihalogenated vinyl ethers
Beilstein J. Org. Chem. 2024, 20, 2691–2703, doi:10.3762/bjoc.20.226
- Fluoroalkenes are one of the important frameworks for a wide range of industrial fields. For example, they are used as a bioisostere of amide bonds in medicines and agrochemicals, and contribute to the synthesis of peptide medicines that are stable to enzymatic metabolism and possess high lipophilicity [1]. In
Base-promoted cascade recyclization of allomaltol derivatives containing an amide fragment into substituted 3-(1-hydroxyethylidene)tetronic acids
Beilstein J. Org. Chem. 2024, 20, 2585–2591, doi:10.3762/bjoc.20.217
- Andrey N. Komogortsev Constantine V. Milyutin Boris V. Lichitsky N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Pr., 47, Moscow, 119991, Russian Federation 10.3762/bjoc.20.217 Abstract For the first time, recyclization of allomaltol derivatives with an amide
- present communication we have studied the recyclization of amide-containing allomaltol derivatives 3 under action of CDI (Scheme 1B). In this case, the interaction also leads to substituted tetronic acids 4. Wherein, in contrast to related hydrazide derivatives 1 the considered process can be realized
- only in the presence of a strong base (DBU). Results and Discussion The starting allomaltols 3 bearing an amide fragment in the side chain were prepared by reaction of dihydropyranones 5 with appropriate amines 6 applying the previously described method [33][34] (Scheme 2). At first, amide 3a was
A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis
Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214
- oxidized to [Co(III)]+ at the anode, while MeOH undergoes cathodic reduction to form MeO− and H2. The MeO− then deprotonates the carbamate, and the resulting conjugated base is oxidized by the cobalt–salen complex [Co(III)]+, generating an amide radical. This amide radical initiates radical cyclization to
- electrolyte, and carbon felt and platinum plate as electrodes, the intramolecular hydroamination proceeded smoothly, yielding azetidines in moderate to good yields. This method was applied to the LSF of celecoxib, zonisamide, and dansyl amide (Scheme 33a). Additionally, the allylation of aldehydes also
- late-stage functionalizations. In 2020, Ackermann and coworkers reported the challenging C–H alkoxylation of (hetero)arenes with sterically encumbered secondary alcohols via a nickel electrocatalyzed protocol [49]. A traceless removable quinoline amide in the meta position was employed as a directing
Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams
Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210
- -amidyl radicals uses activated N–O amide derivatives capable of generating amidyl radicals through fragmentation [18][19]. The direct formation of amidyl radicals in the presence of a carbon alkyl chain could lead to a competitive 1,5-hydrogen atom transfer (1,5-HAT) [20][21][22], limiting the direct
- functionalization of amides with alkenes under photoredox conditions. Another viable approach for amide functionalization through photoredox catalysis involves the nucleophilic addition, in the presence of base, of an amide to a radical cation obtained by oxidation of an unfunctionalized alkene moiety (Figure 1A
- their investigation of the hydrofunctionalization reaction of unsaturated amides and thioamides [28]. They have found that the oxygen atom of the amide group, rather than the nitrogen atom, acted as a nucleophile, leading to the formation of 2-oxazolines and 2-thiazolines. Another recent example of
Hypervalent iodine-mediated cyclization of bishomoallylamides to prolinols
Beilstein J. Org. Chem. 2024, 20, 2455–2460, doi:10.3762/bjoc.20.209
- the alkene and the amide increased from two to three atoms. In the latter case, cyclization at the amide nitrogen to form the pyrrolidine ring was favored over cyclization at the amide oxygen. A DFT study was undertaken to rationalize the change in mechanism of this cyclization process. In addition
- amide at both the oxygen and the nitrogen, however, the ΔG‡ value for the latter was lower by 2.5 kcal·mol−1. This demonstrates a clear kinetic preference for formation of the five-membered ring over the seven-membered one [19]. Subsequent deprotonation of 11 leads to tertiary amide 12. Upon cyclization
- , the iodane moiety in 12 is eliminated by an intramolecular attack by the amide nitrogen to form the aziridinium 13. Finally, ring-opening by SN2 attack of trifluoroacetate leads to the final product 14 [20]. In this case, the kinetic pyrrolidine product is obtained due to the electron-withdrawing
Evaluating the halogen bonding strength of a iodoloisoxazolium(III) salt
Beilstein J. Org. Chem. 2024, 20, 2401–2407, doi:10.3762/bjoc.20.204
- . Finally, the potential as halogen-bonding activator was benchmarked in solution in the gold-catalyzed cyclization of a propargyl amide. Keywords: diaryliodonium; gold catalysis; halogen bonding; hypervalent iodine; non-covalent interactions; Introduction The compound class of diaryliodonium (DAI) salts
- applied as catalyst for the cyclization of propargylic amide 11, a typical benchmark reaction in gold catalysis (Scheme 2) [24][25][26][27], which had previously already been activated by iodine(I) and iodine(III)-based XB donors [15][18]. To evaluate the activity of the new iodoloisoxazolium 7BArF, it
- preactivation process between the XB donor, the gold complex, or the amide can be assumed. Such a sigmoidal curve for this reaction has also been observed in one of the previous studies on the XB activation of gold complexes [15]. The prototypic iodolium 1BArF showed significantly better results reaching ≈85
Asymmetric organocatalytic synthesis of chiral homoallylic amines
Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201
- employing chiral Brønsted acid catalyst (S)-TRIP (118) (Scheme 25). In this approach, the racemic β-formyl amide forms the iminium intermediate that undergoes fast equilibration via the enamine tautomer to form preferentially one enantiomer which then undergoes the acid-catalysed aza-Cope rearrangement
- , creating the desired syn-(2R,3S)-homoallylic amine 120 in high diastereo- and enantioselectivity. The reaction was tested with various aryl, benzyl, allyl, and alkyl-functionalised β-formyl N-morpholinyl amides 119; the amide function was also varied. Yields were scattered across the 31–90% range, with the
- diastereoselectivities varying from 1.1:1 to >20:1 (Scheme 25). Interestingly, almost all isolated products, except for the amine resulting from methyl β-formyl N-morpholinyl amide (119, R = Me), showed dr > 20:1. Enantioselectivity followed the trend and varied between 64–94%, the lowest being obtained for the methyl
Tandem diazotization/cyclization approach for the synthesis of a fused 1,2,3-triazinone-furazan/furoxan heterocyclic system
Beilstein J. Org. Chem. 2024, 20, 2342–2348, doi:10.3762/bjoc.20.200
- candidates are also unveiled. Results and Discussion We started our investigations toward the development of the desired synthetic approach to [1,2,5]oxadiazolo[3,4-d][1,2,3]triazin-7(6H)-one 2-oxides 1 using functionalized furoxans 2 and 3 as suitable substrates. The starting amide precursors 2 were
- , whether isolated or generated in situ, may undergo various controlled transformations [42]. However, previously, we failed to introduce amino-1,2,5-oxadiazoles bearing an amide functionality into the diazotization protocol, arguably due to an increased electron-withdrawing effect and elevated instability
- of thus generated diazonium salts. In this regard, amide 2a and mesitylene were selected as model objects to optimize the reaction conditions, since azo coupling of (1,2,5-oxadiazolyl)diazonium salts with electron-donating arenes is known to proceed quantitatively [42]. We varied the diazotization
Deuterated reagents in multicomponent reactions to afford deuterium-labeled products
Beilstein J. Org. Chem. 2024, 20, 2270–2279, doi:10.3762/bjoc.20.195
- isocyanide component to afford α-aminoacyl amide derivatives 1a–g in good yield (Scheme 3). A [D1]-aldehyde and [D1]-isocyanide were independently used in conjunction with supporting reagents to afford 1b–d and 1e and 1f, respectively, with no observation of deuterium scrambling. A post-condensation
Selective hydrolysis of α-oxo ketene N,S-acetals in water: switchable aqueous synthesis of β-keto thioesters and β-keto amides
Beilstein J. Org. Chem. 2024, 20, 2225–2233, doi:10.3762/bjoc.20.190
- N,S-acetals; β-keto amide; β-keto thioester; dodecylbenzenesulfonic acid; hydrolysis; Introduction In the past decades, the application of easily available and stable α-oxo ketene N,S-acetals as significant synthons has received more and more attention in organic synthesis due to their unique
- form adduct I', which is then transformed into intermediate II' by elimination of ethanethiolate. Subsequently, β-keto amide 3a is obtained when II' releases H+. Conclusion In summary, we have successfully developed an environmentally friendly method for the selective aqueous synthesis of β-keto
Natural resorcylic lactones derived from alternariol
Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187
Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis
Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182
- radical, which induces 5-exo cyclization. The following hydrogen abstraction, intramolecular ionic cyclization, and hydrolysis during chromatography on silica gel affords the cyclic amide in good yield. They further applied this radical cyclization reaction as a key step in the synthesis of (±)-α-kainic
Solvent-dependent chemoselective synthesis of different isoquinolinones mediated by the hypervalent iodine(III) reagent PISA
Beilstein J. Org. Chem. 2024, 20, 1914–1921, doi:10.3762/bjoc.20.167
- deprotonation with sulfamate, gives the 4-substituted isoquinolinone derivative 2a (Scheme 6). Looking into the formation of 2c' from 1c (Scheme 2), two other resonance structures for the initially formed intermediate 1CC, namely 1CC' and 1CC'', are shown in Scheme 7. The oxygen atom in the amide motif of the
- substrate 1c may act as an electrophilic center, forming a C–O bond with the alkenyl group to give the isochromen-1-one oxime product 2c'. When wet HFIP was used as the solvent, the reaction followed a different pathway. HFIP, a strong hydrogen bonding donor [26][27][28], interacts with the amide moiety of
- the substrate, and thus preventing the possible interaction between the amide moiety and PISA, as opposed to CH3CN. The olefin moiety of the complex then interacts with the exposed central iodine(III) atom in PISA [25], forming the intermediate D. Similar cyclic iodonium intermediates were also
Chiral bifunctional sulfide-catalyzed enantioselective bromolactonizations of α- and β-substituted 5-hexenoic acids
Beilstein J. Org. Chem. 2024, 20, 1794–1799, doi:10.3762/bjoc.20.158
- catalysts. Asymmetric bromolactonizations of model substrate 2a with amide- and urea-type chiral bifunctional sulfides (S)-5 and 6, known to be effective for other asymmetric halocyclizations [32][33][34][35], resulted in δ-valerolactone product 3a with low enantioselectivities (50:50 and 56:44 er
Oxidative fluorination with Selectfluor: A convenient procedure for preparing hypervalent iodine(V) fluorides
Beilstein J. Org. Chem. 2024, 20, 1785–1793, doi:10.3762/bjoc.20.157
- difluoroiodanes 7a and 7b containing the amide sidearms would have an even more acute N–I–N bond angle (156.6–156.9 °). Furthermore, the internal chelate NCC bond angle in 7a/b (111.7°) was calculated to be bigger than the corresponding OCC angle (108.3(5)° to 109.2(5)°) in 6 due to the sp2-hybridised carbon in
Ugi bisamides based on pyrrolyl-β-chlorovinylaldehyde and their unusual transformations
Beilstein J. Org. Chem. 2024, 20, 1773–1784, doi:10.3762/bjoc.20.156
- -called convertible isocyanides [27][28][29][30][31][32][33][34][35][36] in Ugi-4CR makes it possible to obtain carboxylic acids or esters after hydrolysis of the secondary amide group in the Ugi products (Scheme 2) [27][28][29][31][32][34][35][36]. Ugi bisamides modified in this way may be subsequently
- which the Z-configuration of the chlorovinyl fragment was detected. Post-Ugi transformations As previously mentioned [32], the introduction of the convertible 2‑bromo-6-isocyanopyridine into the Ugi bisamide structure allows the conversion of the newly formed amide into a carboxylic acid fragment after
- acid hydrolysis. Similar results were obtained by Dömling and co-workers [27], who used 2-nitrobenzyl isocyanide as a universal convertible isocyanide, and the amide group was also converted into a carboxylic acid under the conditions of acid hydrolysis (Scheme 2). Therefore, taking into account the
Harnessing unprotected deactivated amines and arylglyoxals in the Ugi reaction for the synthesis of fused complex nitrogen heterocycles
Beilstein J. Org. Chem. 2024, 20, 1758–1766, doi:10.3762/bjoc.20.154
- amide substituent in C3 is pseudoaxially oriented in an all-trans conformation, only the unlike attack would be allowed (Scheme 3). On the other hand, when 3-bromopropanamine was used, the formation of the pyrrolobenzodiazepinone system 8 was observed albeit along with benzodiazepinone 5c (Scheme 4). In
Syntheses and medicinal chemistry of spiro heterocyclic steroids
Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152
- ). Spiro tetraoxanes were tested for their antimalarial activity. From the biological results, it was observed that compounds with an amide moiety were more active compared to those possessing an ester or a carboxylic group. It was observed that tetraoxanes with a primary amide were more active towards
Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations
Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151
- synthesis of the bis-THIQ alkaloid family, Oguri and Oikawa utilized the NRPS module SfmC to construct a highly functionalized scaffold from amino acid derivatives (Scheme 10) [102]. The total synthesis of 5 from original biosynthetic intermediate 93 requires regioselective amide bond cleavage to remove the
- this problem, the research group designed synthetic substrate analogs (96, 101) that mimic the biosynthetic intermediate 88 (Scheme 10A). By replacing an amide linkage in 88 with an ester linkage, the fatty acid side chain could be removed under mild conditions after enzymatic construction of the
Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry
Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147
- . Additionally, stereoselectivity can be achieved by using potassium bis(trimethylsilyl)amide for deprotonation and methylation with MeI [33][39]. Any of these routes would yield methylated amino acids that can then be incorporated into an oligopeptide in solid-phase peptide synthesis (SPPS). Additionally, N
- -methylation concurrently to peptide synthesis is also possible. Commonly used methods for SPPS of N-methylated peptides involve activating the amino group with 2-nitrobenzenesulfonamide and methylating agents, such as dimethyl sulphate [40][41][42]. Directly methylating peptides is challenging. Multiple amide
- occur at the N-terminal amide, the peptide backbone, as well as on amino acid side chain amides (Figure 1). While traditional synthesis of N-methylated peptides is challenging and time consuming, installation via RiPP maturases provides an easier, quicker, and greener approach to confer these attributes
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