Synthesis and cytotoxicity studies of novel N-arylbenzo[h]quinazolin-2-amines

• Battini Veeraiah,
• Kishore Ramineni,
• Dabbugoddu Brahmaiah,
• Nangunoori Sampath Kumar,
• Hélène Solhi,
• Rémy Le Guevel,
• Chada Raji Reddy,
• Frédéric Justaud and
• René Grée

Beilstein J. Org. Chem. 2024, 20, 2592–2598, doi:10.3762/bjoc.20.218

• afforded the known aldehyde 2 in 65% yield [13]. Then, reaction with guanidinium carbonate in DMA at high temperature [12], gave the desired intermediate 2-aminobenzo[h]quinazoline (3). In a final step, classical Buchwald–Hartwig coupling [14][15][16][17] with bromobenzene under the conditions described

Base-promoted cascade recyclization of allomaltol derivatives containing an amide fragment into substituted 3-(1-hydroxyethylidene)tetronic acids

• Andrey N. Komogortsev,
• Constantine V. Milyutin and
• Boris V. Lichitsky

Beilstein J. Org. Chem. 2024, 20, 2585–2591, doi:10.3762/bjoc.20.217

• additional nitrogen atoms in compounds 4 leads to the fact that the other tautomeric form becomes more favorable. A proposed mechanism of the investigated recyclization is presented in Scheme 4. Initially, imidazolide A is formed via condensation of the starting amide 3 with CDI. Then, intermediate A

• . Finally, neutralization of intermediate E by HClconc leads to target product 4. It is interesting to note that chemical properties of the synthesized furanones differ from previously described 3-acetyltetronic acids 2 obtained from the corresponding hydrazides 1. As it was shown in a prior paper compounds

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• carbocation intermediate, which rearomatizes through proton loss. Concurrently, the cathodic reduction of the generated protons produces H2. In addition to (hetero)aromatic groups, alkene scaffolds also underwent this reaction (Scheme 3). In the same year, the Lei group [10] extended the electrochemical C(sp2

• subsequent C–H abstraction. The methylarene undergoes oxidation, deprotonation, and a second oxidation before being captured by MeOH to produce a monomethoxylated product. This intermediate then undergoes a second oxidation round to yield the final product. Additionally, the same group disclosed an aromatic

• . Subsequently, the generated intermediate 29 is oxidized at the anode, then attacked by the acid to obtain the final product (Scheme 10). C–H bond sulfur functionalization: The direct formation of the CS bond is an attractive way to prepare aryl sulfides. From this perspective, Wu and coworkers developed a

Visible-light-mediated flow protocol for Achmatowicz rearrangement

• Joachyutharayalu Oja,
• Sanjeev Kumar and
• Srihari Pabbaraja

Beilstein J. Org. Chem. 2024, 20, 2493–2499, doi:10.3762/bjoc.20.213

• , [Ru(bpy)3]2+ undergoes transition to [Ru(bpy)3]2+* which is quenched by persulfate resulting in [Ru(bpy)3]3+ along with the simultaneous generation of sulfate and a sulfate radical. SET from furfuryl alcohol closes the catalytic cycle of the PC and an intermediate A is generated with L (L = SO4−· or

• OH). The Achmatowicz product is formed by addition of water to oxocarbenium intermediate A followed by elimination of L. Conclusion In conclusion, an integrated continuous PFR platform for photocatalytic functionalization of furfuryl alcohols to dihydropyranones through an Achmatowicz rearrangement

Machine learning-guided strategies for reaction conditions design and optimization

• Lung-Yi Chen and
• Yi-Pei Li

Beilstein J. Org. Chem. 2024, 20, 2476–2492, doi:10.3762/bjoc.20.212

• , telescoped flow sequences [206][207][208] or one-pot batch synthesis [209] emphasize the use of chemically compatible reagents and solvents in each reaction step to minimize intermediate purification steps. Volk et al. [210] developed AlphaFlow, which utilizes reinforcement learning as an optimization

Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams

• Valentina Giraldi,
• Giandomenico Magagnano,
• Daria Giacomini,
• Pier Giorgio Cozzi and
• Andrea Gualandi

Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210

• ) [23][24][25]. The nucleophilic attack of the nitrogen atom on the oxidized C=C double bond results in the formation of a radical intermediate after deprotonation. This radical intermediate can proceed through various pathways (e.g., HAT, oxidation) to yield the desired final product. In the

• carboaminations. However, photoredox catalysis could be applied to a suitable β-lactam intermediate decorated with an alkene moiety to achieve N–H addition and cyclization to the fused bicyclic system of clavams (Figure 2A). Clavulanic acid (1, Figure 2B) belongs to the family of clavam β-lactam compounds and is

• from the commercially available β-lactam 9, a key intermediate for the industrial preparation of carbapenems. Starting from the reaction conditions reported by Nicewicz and Morse [28], we optimized the conditions with compound 8c as the model substrate for the photoredox cyclization (Table 1). The

Hypervalent iodine-mediated cyclization of bishomoallylamides to prolinols

• Smaher E. Butt,
• Konrad Kepski,
• Jean-Marc Sotiropoulos and
• Wesley J. Moran

Beilstein J. Org. Chem. 2024, 20, 2455–2460, doi:10.3762/bjoc.20.209

• an associative pathway where one of the TFA ligands dissociates from 8 upon approaching the substrate and forms the intermediate 9. The calculated ΔG‡ value is quite high here, which could explain the low yield obtained after 16 hours. However, for the cyclization of N-allylbenzamide (1a), we found

Synthesis and conformational analysis of pyran inter-halide analogues of ᴅ-talose

• Olivier Lessard,
• Mathilde Grosset-Magagne,
• Paul A. Johnson and
• Denis Giguère

Beilstein J. Org. Chem. 2024, 20, 2442–2454, doi:10.3762/bjoc.20.208

• ][25][26][27][28][29][30], such as the solution-state conformation of diastereomeric polyfluorohexitols [31]. Herein, we report the synthesis of pyran inter-halide analogues of ᴅ-talopyranose 6, integrating also the 2,3-cis, 3,4-cis relationship for the halogens, from known intermediate 5 (Figure 1b

Phenylseleno trifluoromethoxylation of alkenes

• Clément Delobel,
• Armen Panossian,
• Gilles Hanquet,
• Frédéric R. Leroux,
• Fabien Toulgoat and
• Thierry Billard

Beilstein J. Org. Chem. 2024, 20, 2434–2441, doi:10.3762/bjoc.20.207

• compounds from alkenes and DDPyOCF3, more precisely to α-trifluoromethoxylated, β-phenylselenylated compounds. Results and Discussion The electrophilic addition of phenylselenyl halides to alkenes to form a selenonium intermediate that can be intercepted by an external nucleophile is a well-known method to

Facile preparation of fluorine-containing 2,3-epoxypropanoates and their epoxy ring-opening reactions with various nucleophiles

• Yutaro Miyashita,
• Sae Someya,
• Tomoko Kawasaki-Takasuka,
• Tomohiro Agou and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2024, 20, 2421–2433, doi:10.3762/bjoc.20.206

• the characteristics of the resultant intermediate which could lead to the realization of the addition of such nucleophilic species. First of all, as shown in Table 4, we started to investigate the reactivity of 2b toward sodium malonate as the representative nucleophile. Because a brief solvent search

• carried out for the verification of the intermediate leading to the product 11. Although we initially assumed that the epoxy ring opening occurred by hydride generated through the β-elimination of the n-C10H21MgBr-based cuprate species, the TLC analysis of the reaction mixture did not show any evidence of

• corresponding intermediate by D2O proved that no deuteration occurred. This result clearly indicated that hydride was released from the t-Bu group of the Cu(III) species formed after the nucleophilic attack of the epoxy ring. In our case, since the strongly electron-withdrawing CF3 group would render the rate

Homogeneous continuous flow nitration of O-methylisouronium sulfate and its optimization by kinetic modeling

• Jiapeng Guo,
• Weike Su and
• An Su

Beilstein J. Org. Chem. 2024, 20, 2408–2420, doi:10.3762/bjoc.20.205

• 10.3762/bjoc.20.205 Abstract Nitration of O-methylisouronium sulfate under mixed acid conditions gives O-methyl-N-nitroisourea, a key intermediate of neonicotinoid insecticides with high application value. The reaction is a fast and highly exothermic process with a high mass transfer resistance, making

• insecticides is increasing as the world’s food crisis intensifies due to the changes in the natural environment and ongoing geopolitical crises [1]. O-Methyl-N-nitroisourea (NIO) is a pivotal pesticide intermediate in the preparation of nitroguanidine derivatives, which are the raw material for highly

• of dicyclopentadiene (DCPD) in a continuous flow microreactor [15]. Where cyclopentadiene was the target intermediate formed by the thermal dissociation of dicyclopentadiene, cascade oligomerization was a side reaction to be avoided. Based on the deep understanding of the kinetic differences between

Efficient one-step synthesis of diarylacetic acids by electrochemical direct carboxylation of diarylmethanol compounds in DMSO

• Hisanori Senboku and
• Mizuki Hayama

Beilstein J. Org. Chem. 2024, 20, 2392–2400, doi:10.3762/bjoc.20.203

• intermediates at the anode. The produced acetate ion D and a magnesium ion form the salt E, which upon acid treatment during workup gives a diphenylacetic acid 2. The effects of DMSO as solvent are not clear at present, and one reasonable and acceptable aspect might be the solubility of the salt of intermediate

• B in DMSO solvent. Electrochemical reduction of intermediate B should occur in solution, and this would mean that intermediate B must be dissolved in the solvent used. DMSO is well known as a good solvent for dissolving organic metal salts. In this electrochemical reaction medium, a main counter

• cation of intermediate B is thought to be the magnesium ion, and the magnesium salt of B must be dissolved in the solvent. Although other magnesium salts, such as magnesium carbonate and magnesium oxalate, are also generated during the electrolysis, the magnesium salt of B would be dissolved sufficiently

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• concerted SN2-key intermediate 60 must be at least 18.9 kcal/mol more favoured than a separated imine–chloride ion pair 61 attacked by the free allylsilane (Figure 3). Altogether, the developed methodology can be formally viewed as a useful tool for the enantioselective synthesis of chiral α-carboxyl-2,3

• commercially available derivative of ʟ-proline, (S)-(−)-α,α-bis(3,5-dimethylphenyl)-2-pyrrolidinemethanol (62) (Scheme 12). This catalyst is capable of asymmetric activation of N-(2-hydroxyphenyl)imines through the reversible chelation to the N-(2-hydroxyphenyl) group, forming a rigid intermediate, while the

• , the latter acting as a catalytically active species. After the addition of 1 equiv of imine 73 at −40 °C, proton Ha of 72 shifted upfield which was close to what was observed in the TfOH adduct 71, and which supported the formation of intermediate 74. The authors estimated the equilibrated ratio

Tandem diazotization/cyclization approach for the synthesis of a fused 1,2,3-triazinone-furazan/furoxan heterocyclic system

• Yuri A. Sidunets,
• Valeriya G. Melekhina and
• Leonid L. Fershtat

Beilstein J. Org. Chem. 2024, 20, 2342–2348, doi:10.3762/bjoc.20.200

• obtained. Thus, we have demonstrated that the terminal nitrogen atom in the diazonium fragment of intermediate 9 becomes the N5 atom of compound 8 (corresponding 15N NMR spectra are provided in Supporting Information File 1). To explore the potential application of the obtained compounds 1 and 7, we

Hydrogen-bond activation enables aziridination of unactivated olefins with simple iminoiodinanes

• Phong Thai,
• Lauv Patel,
• Diyasha Manna and
• David C. Powers

Beilstein J. Org. Chem. 2024, 20, 2305–2312, doi:10.3762/bjoc.20.197

• -disubstituted olefins is observed and interpreted as evidence that aziridination proceeds via a carbocation intermediate that subsequently cyclizes. These results demonstrate a simple method for activating iminoiodinane reagents, provide analysis of the extent of activation achieved by H-bonding, and indicate

• fashion. The dissimilarity of the diastereomeric ratios from cis- and trans- starting materials indicates that the potential intermediate is too short lived for complete ablation of the starting material stereochemistry. Second, the aziridination of cyclopentene by PhINTs in the presence of a radical trap

• iminoiodinane reacts directly with the olefin to generate a short-lived alkyl-bound iodinane 7 or iodonium species 8 (Scheme 4f). Ligand coupling from 7 or extrusion of iodobenzene from 8 would furnish a carbocation intermediate 9 which could undergo C–C bond rotation prior to ring closure to form the aziridine

Deuterated reagents in multicomponent reactions to afford deuterium-labeled products

• Kevin Schofield,
• Shayna Maddern,
• Yueteng Zhang,
• Grace E. Mastin,
• Rachel Knight,
• Wei Wang,
• James Galligan and
• Christopher Hulme

Beilstein J. Org. Chem. 2024, 20, 2270–2279, doi:10.3762/bjoc.20.195

• been demonstrated to work without loss of deuterium in the Ugi-3CR. First reported in 1961, the Ugi-azide reaction differs from the classical Ugi 4-CR in that an azide anion traps out the intermediate nitrilium ion, leading to formation of α-aminotetrazoles [36][37][38][39]. Thus, it comprises reaction

• (Scheme 8) [47]. The Groebke–Blackburn–Bienaymé (GBB) reaction is an intramolecular variant of the Ugi reaction where the intermediate nitrilium ion is intercepted by heteroatoms from the amino-heterocyclic input. Discovered in 1998, and reported independently by three different research groups, it is a

gem-Difluorination of carbon–carbon triple bonds using Brønsted acid/Bu₄NBF₄ or electrogenerated acid

• Mizuki Yamaguchi,
• Hiroki Shimao,
• Kengo Hamasaki,
• Keiji Nishiwaki,
• Shigenori Kashimura and
• Kouichi Matsumoto

Beilstein J. Org. Chem. 2024, 20, 2261–2269, doi:10.3762/bjoc.20.194

• the use of HF or its complexes as a reagent. These reactions seem to proceed via the formation of the vinyl fluoride as the intermediate [25][26][27][28]. In the first example, Olah and co-workers reported the reaction of terminal alkynes with HF/pyridine (Olah reagent) (Figure 1, reaction 1) [29][30

• electricity was passed to the solution. A plausible reaction mechanism for the current reactions is described in Scheme 3. The reaction of carbon–carbon triple bonds and H+ species, which are derived from the Brønsted acid (in method A) or EGA (in method B), gives the vinylic carbocation intermediate A, which

• can react with BF4− to give fluorinated alkene B [57][58][59][60]. In the next step, B can undergo the second addition of H+, followed by the incorporation of F− into the carbocation intermediate C, forming the difluorinated compound 2a. The carbocation adjacent to the F atom might be stabilized by

Synthesis and reactivity of the di(9-anthryl)methyl radical

• Tomohiko Nishiuchi,
• Kazuma Takahashi,
• Yuta Makihara and
• Takashi Kubo

Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193

• radical. The unpaired electron is primarily located at the central sp2 carbon, a highly reactive site. The DAntM radical readily reacts with oxygen, leading to 1,2-dioxetane intermediate and decomposition to give anthryl aldehyde and a stable anthroxyl radical. Results and Discussion The synthetic route

• pathway involving hydrogen abstraction from water yielding 4, and a major pathway involving oxygen addition to the central carbon to afford 1,2-dioxetane (DOT) intermediate. Usually, DOT derivatives are known to readily decompose [38], and this DOT intermediate is also considered to decompose upon C–C and

• formation of a 1,2-dioxetane (DOT) intermediate and decomposition to aldehyde 1 and anthroxyl radical 5 via C–C and O–O bond cleavage. This reactivity is attributed to the predominant localization of an unpaired electron at the central sp2 carbon of the DAntM radical. These findings provide variable

Selective hydrolysis of α-oxo ketene N,S-acetals in water: switchable aqueous synthesis of β-keto thioesters and β-keto amides

• Haifeng Yu,
• Wanting Zhang,
• Xuejing Cui,
• Zida Liu,
• Xifu Zhang and
• Xiaobo Zhao

Beilstein J. Org. Chem. 2024, 20, 2225–2233, doi:10.3762/bjoc.20.190

• above and on literature precedents [40][41], a plausible mechanistic pathway for the formation of 2 and 3 is shown in Scheme 5 (with the reaction of 1a as an example). In the presence of DBSA, the protonation of 1a results in the carbocation intermediate I. Then, the nucleophilic attack of H2O at the

• carbocation of I produces intermediate II, which converts into intermediate III through a deprotonation–protonation process. Finally, the elimination of PhNH2 from intermediate III occurs to afford the desired product 2a. In the presence of NaOH, the Michael addition between 1a and base initially occurs to

• 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

Heterocycle-guided synthesis of m-hetarylanilines via three-component benzannulation

• Andrey R. Galeev,
• Maksim V. Dmitriev,
• Alexander S. Novikov and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2024, 20, 2208–2216, doi:10.3762/bjoc.20.188

• intramolecular addition of enamine I to the C3=O to form intermediate II, which dehydrates to cyclic carbinol III. Finally, dehydration of intermediate III yields anilines 3. Conclusion In summary, a method for the synthesis of substituted meta-hetarylanilines under mild conditions starting from 1,3-diketones

Natural resorcylic lactones derived from alternariol

• Joachim Podlech

Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187

• developed [121][122]. 3-O-Methylalternariol (3) was isolated as a natural product only once from a non-specified Alternaria sp. [123] and its structure was confirmed by comparison with an intermediate obtained during the total synthesis of alternariol [66]. 3,9-O,O-Dimethylalternariol (4) was first isolated

• , vide infra), which leads to a variety of further metabolites. 4-Hydroxyalternariol (19) was first identified as intermediate of the human, rat, and porcine metabolism [102][103][117][150], but was later similarly found to be a fungal natural product in Alternaria sp. [155], A. tenuissima [156], and

• Trichoderma (Hypocrea) sp. [157]. It is quite astonishing that this assumed main intermediate in the biosynthetic downstream of alternariol was identified as natural product only recently (2021) and that no biological properties were established. The respective 4-hydroxy derivative of 9-O-methylalternariol

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• truxenes with freshly distilled pyrrole using trifluoroacetic acid (TFA) as an acidic catalyst afforded the anticipated DPM-appended truxene derivatives (14, 16 and 18) in good yields (60–80%). All the newly prepared DPM-linked truxene-hybrid molecules as well as the intermediate acetylated truxene

Factors influencing the performance of organocatalysts immobilised on solid supports: A review

• Zsuzsanna Fehér,
• Dóra Richter,
• Gyula Dargó and
• József Kupai

Beilstein J. Org. Chem. 2024, 20, 2129–2142, doi:10.3762/bjoc.20.183

• systems [104][105][106] and dendrimers [107][108][109] have also emerged as alternative soluble supports for catalyst immobilisation. In these systems the catalyst moieties can be built in at the core, at the periphery, or at intermediate positions, affecting the catalytic performances differently [110

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

• Akiya Ogawa and
• Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

• •). The formed R’S• adds to isocyanide (RNC) to generate imidoyl radical intermediate 2 (E = R’S), which abstracts hydrogen from thiol to give the corresponding thioformimidate 3 (E = R’S) with regeneration of R’S•. Thus, the hydrothiolation of isocyanides with thiols proceeds by the radical chain

• substituents on the heteroatom. For this reason, the 1,1-addition is less likely to proceed as with group 16 or 15 heteroatom radicals. In the case of stannyl and silyl radicals, the alkyl group of the isocyanide is eliminated as an alkyl radical from the imidoyl radical intermediate 2 [42]. The formed alkyl

• addition of radical species to the isocyano group of 29 to form the imidoyl radical 30 as a key intermediate, which adds intramolecularly to the ortho-aryl group. The subsequent aromatization with the release of hydrogen (or proton) affords 31 in good yields. Nanni et al. reported the reaction of 2

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• methodology demands that all sequences have to be performed in the same reaction vessel; neither intermediate work-up, filtration of byproducts, nor solvent exchange by evaporation falls within the scope of MCR. Therefore, this review aims to present and discuss the concepts of ring-forming MCR syntheses of

• -phenyl-2,4-hexanedione was generated in situ through acid hydrolysis of 1,1,1-trichloro-4-methoxy-6-phenyl-3-hexen-2-ones 71. Subsequent cyclization with hydrazine hydrochloride followed by hydrolysis of the trichloromethyl group led to 73. This intermediate was then reacted with 2,2,2-trifluoroethanol

• fluoropyrazoles from fluorinated 1,3-dielectrophiles represents a crucial synthetic pathway. For example, 1,1,2,2-tetrafluoro-N,N-dimethylethan-1-amine (TFEDMA) (82) can be activated using BF3·OEt2 to generate an iminium salt 84 with increased electrophilicity. Subsequently, this intermediate reacts with various