Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

• whereas heating it in 75% acetic acid solution produced the deprotected compound but migration of the acyl group from the sn-2 to the sn-3 position lead to an inseparable mixture of regioisomers. A selective desilylation of 12.5 was finally achieved with BF3·Et2O producing 12.6 without migration of the

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• benzonitrile acceptor core. We found that the material is formed as a mixture of the rotational isomers that do not experience interconversion upon heating the 4BGIPN solution in DMSO to 120 °C. Two rotational isomers were successfully crystallized to show different up and down orientations of the

New one-pot synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones based on 5-aminopyrazoles and azlactones

• Vladislav Yu. Shuvalov,
• Ekaterina Yu. Vlasova,
• Tatyana Yu. Zheleznova and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2023, 19, 1155–1160, doi:10.3762/bjoc.19.83

• ]pyridones 3 obtained by this method vary widely [31][32][33]. Solvent-free reactions are convenient from both economic and environmental points of view. We obtained tetrahydro-1H-pyrazolo[3,4-b]pyridinone 3a by heating 5-aminopyrazole 1 with azlactone 2a in the absence of solvent at 150 °C in 62% yield

• -aminopyrazoles 1, 5, 6 and azlactones 2a–i, followed by heating the resulting intermediate in DMSO in the presence of t-BuOK. Photophysical properties of the obtained compounds were studied. Biologically active 4-arylpyrazolo[3,4-b]pyridin-6-ones. Normalized absorption and fluorescence spectra of solutions of

Synthesis of imidazo[4,5-e][1,3]thiazino[2,3-c][1,2,4]triazines via a base-induced rearrangement of functionalized imidazo[4,5-e]thiazolo[2,3-c][1,2,4]triazines

• Dmitry B. Vinogradov,
• Alexei N. Izmest’ev,
• Angelina N. Kravchenko,
• Yuri A. Strelenko and
• Galina A. Gazieva

Beilstein J. Org. Chem. 2023, 19, 1047–1054, doi:10.3762/bjoc.19.80

• prepare the corresponding carboxylic acids 4 using an aqueous KOH solution. Heating esters 1a,b in an aqueous solution of KOH and subsequent addition of hydrochloric acid led to the corresponding acids 4a,b as the main products. Acids 4a,b were isolated from the mixtures in 17 and 38% yield, respectively

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• , and NI-PTZ-Ph-O. Temperature range: 25–800 °C, heating rate: 10 °C/min in N2 atmosphere. Femtosecond transient absorption spectra of NI-PTZ-F. (a) Transient absorption spectra and (b) the EADS obtained with global analysis in HEX. Femtosecond transient absorption spectra of NI-PTZ-F-O. (c) Transient

CO₂ complexation with cyclodextrins

• Cecilie Høgfeldt Jessen,
• Jesper Bendix,
• Theis Brock Nannestad,
• Heloisa Bordallo,
• Martin Jæger Pedersen,
• Christian Marcus Pedersen and
• Mikael Bols

Beilstein J. Org. Chem. 2023, 19, 1021–1027, doi:10.3762/bjoc.19.78

• coverage of the bottom. The analysis shown in Figure 3 was started at 28 °C, and was finished at a temperature of 150 °C with a heating rate of 5 °C/min. Determination of dissociation constants between 7 and CD’s. Samples were prepared that consisted of citrate-phosphate buffer (pH 3, 50 mM), 7 (40 μM) and

Synthesis of tetrahydrofuro[3,2-c]pyridines via Pictet–Spengler reaction

• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2023, 19, 991–997, doi:10.3762/bjoc.19.74

• overnight (Table 1, entries 15 and 16). Finally, we found that the optimal reaction time was 5 hours. The yield of the desired product 4a in this case was 67% (Table 1, entry 18). With a shorter time, a slightly reduced reaction yield of 4a was observed, while at longer heating the reaction mixture

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• to reduce energy consumption and the carbon footprint. The traditional heating techniques used to synthesize compounds are being replaced by contemporary green alternative energy systems, such as photocatalysis, microwave irradiation, ultrasonic irradiation, grinding, and ball milling processes

• interaction between DES and the amino group enhance the nucleophlicity of the amines. (3) Microwave-assisted reactions Microwave-assisted heating offers a number of advantages over conventional heating, such as greater precision, excellent product yields, and very rapid reaction. This section describes the

• synthesis of N-substituted pyrroles catalyzed by CeCl3∙7H2O. In this reaction, N-arylpyrroles 75 were synthesized from various aniline derivatives 74 by the reaction with 2,5-dimethoxytetrahydrofuran (2) in both microwave irradiation and conventional heating in acetonitrile (Scheme 36). Furthermore, these N

First synthesis of acylated nitrocyclopropanes

• Kento Iwai,
• Rikiya Kamidate,
• Khimiya Wada,
• Haruyasu Asahara and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

• our study using ethyl acetoacetate (3c) as starting 1,3-dicarbonyl compound according to method b (Scheme 2). After heating an acetonitrile solution of 3c, N-bromosuccinimide, and p-toluenesulfonic acid [7], α-bromoacetoacetate 6c was isolated with a 44% yield after purification of the reaction

Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?

• Lukáš Marek,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61

• formation of products 8a and 8a-Me was observed, but their combined yield was lower than in DMF or MeCN. The introduction of the N-methyl group coming from trimethyl phosphite must occur prior to the dehydration step of the intermediary thiazole 7a because heating of independently prepared 8a with trimethyl

Sulfate radical anion-induced benzylic oxidation of N-(arylsulfonyl)benzylamines to N-arylsulfonylimines

• Joydev K. Laha,
• Pankaj Gupta and
• Amitava Hazra

Beilstein J. Org. Chem. 2023, 19, 771–777, doi:10.3762/bjoc.19.57

• synthetic utility of the developed protocol, a tandem “one-pot” synthesis of N-heterocycles was successfully executed (Scheme 3). Thus, exposition of substrates 1 under the optimized reaction conditions followed by the addition of ortho-substituted anilines 3 and K2S2O8 (1 equiv) and heating the reaction

• cleavage of the peroxy linkage under heating conditions [17]. The hydrogen atom is abstracted from the benzylic position of 1 by SO4·−, generating benzylic radical 1aa [14][15][16]. A single electron transfer (SET) could subsequently occur from 1aa to form the reactive species 1ab. Finally, the base

Honeycomb reactor: a promising device for streamlining aerobic oxidation under continuous-flow conditions

• Masahiro Hosoya,
• Yusuke Saito and
• Yousuke Horiuchi

Beilstein J. Org. Chem. 2023, 19, 752–763, doi:10.3762/bjoc.19.55

• consideration from the time course of the heat of reaction. The adiabatic heating was calculated to be 138 K (see Supporting Information File 1). To suppress the increase of the internal temperature, the amount of AcOH was increased by 40 times (from 3 mL/g to 120 mL/g) for the following evaluation of the

• reaction rate under flow conditions. This dilution suppressed the adiabatic heating to less than 5 K, and the reaction rate could be more precisely evaluated. Evaluation of the reaction rate under continuous-flow conditions The reaction rate was evaluated under continuous-flow conditions using a standard

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• determined for the enantiopure helicenes. For compound 12, the racemization barrier was 24.8 kcal mol−1 at 298 K, which provides a racemization half-life (t1/2) of 24.4 h. For compounds 11 and 13, neither racemization nor decomposition was observed by chiral HPLC after heating hexadecane solutions of each

• racemization was observed by heating the enantiomer for 1 hour at 120 °C. Except for [5]helicene, Narita and co-workers also reported [7]- or [9]helicene-containing chiral NGs [42]. As shown in Scheme 4, dibromo-functionalized 1,2,3,4-tetraphenylbenzene 32 was treated with DDQ and TfOH to produce dibromo 33 as

• the NG precursor 39 by heating dialkyne 38 and tetracyclone 2, which led to two hexarylbenzene units connected by an oxygen linker. Upon treatment of 39 under Scholl reaction conditions (DDQ, TfOH), an oxa-[7]helicene containing chiral NG 40 was obtained in high yield [43]. Meanwhile, they enlarged

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• good yield (80%) by heating 23 in polyphosphoric acid (Scheme 5). Independently, in an effort to synthesise phenothiazine isosteres, Craig et al. [39] prepared 1a via a Wagner–Meerwein rearrangement of 23 with P2O5 (Scheme 5) the following year. The method was used to successfully synthesise

•  8). 2.4 Ring expansion of N-arylindoles (41) The polyphosphoric acid (PPA)-catalysed rearrangement of N-arylindoles 41 was first reported by Tokmakov and Grandberg [48]. The reaction provided moderate yields with a simple 2 step linear sequence from indole 39. The reaction requires heating at

• ] reported the synthesis of substituted dibenzo[b,f]azepines 110 as unexpected products during their investigation of the Catellani reaction. The Pd-catalysed reaction of an aryl iodide 106, bromoaniline 107, norbornadiene (108) and base resulted in the norbornene-azepine intermediate 109. Heating to 130 °C

Nucleophile-induced ring contraction in pyrrolo[2,1-c][1,4]benzothiazines: access to pyrrolo[2,1-b][1,3]benzothiazoles

• Ekaterina A. Lystsova,
• Maksim V. Dmitriev,
• Andrey N. Maslivets and
• Ekaterina E. Khramtsova

Beilstein J. Org. Chem. 2023, 19, 646–657, doi:10.3762/bjoc.19.46

• APBTT 1a with methanol (2a) were optimized. The best yield of PBTA 3aa was observed when methanol was used both as a solvent and a reagent and heated at 65 °C for 1 h (entry 7, Table 1). It is useful to note that, under these conditions, an increase in the heating time (up to 6 h) did not affect the

• of heating the reaction mixture at 65 °C, it contained trace amounts of product 5a and 81 % of product 3aa. Additionally, we have examined the scaling of the reaction of APBTT 1a with methanol (2a). We found that the proposed procedure could be readily scaled up to 1.5 mmol (0.5 g) of APBTT 1a. The

• the model reaction of APBTT 1a and aniline (11a) were optimized. The best yield of PBTA 12aa was observed when butyl acetate was used as the solvent and heated at 130 °C for 3 h (entry 3, Table 3). Heating the reaction mixture in toluene (entry 7, Table 3) showed a good yield too. Since the product

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• degradation under longer heating. In addition, we found that the comp1 [Ru3(CO)11(L1)] was more efficient when the reaction mixture was preheated before being introduced into the reactor at 200 °C. The setup was thus modified (Scheme 3) to include a 0.8-millimeter-diameter stainless-steel preheating loop

• imine in situ. Furthermore, the optimized conditions with the pulsed-flow device proved to be effective, as an NMR yield of 62% of the C3-alkylated imine I2a was obtained by preheating at 130 °C for 5 min in reactor 1 (after introduction of mixture B), followed by heating at 180 °C for 45 min in reactor

• furfural derivatives by C–H activation, a) in batch: previous works, and b) in continuous flow: this work. C3-alkylation of bidentate imine 1 performed in batch. Optimization of the heating for the alkylation reaction on the homemade pulsed-flow setup. Proposed reaction mechanism for the alkylation

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• heating of its MeOH/HCl solution at 60 °C under conditions similar to the ones previously reported for (RCysNi)L4 [42] (see Supporting Information File 1 for details). The corresponding amino acid was obtained, along with the L7 ligand which was recovered in ca. 70% yield and then reused. DFT study The

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• decrease of UV–vis spectra upon heating up to 90 °C and a baseline increase indicated intermolecular stacking and aggregation of compounds, which was more pronounced for Phen-Py-2. Spectroscopic characterization data are given in the Table 1 and Supporting Information File 1, Figure S1. A linker between

• significantly solvent and pH-dependent. Namely, excimer fluorescence was mostly quenched in methanol, where the monomer fluorescence was also very low. Further, excimer fluorescence was quenched in acidic conditions and increased upon pH increase. Also, excimer emission was quenched upon heating without

• molecules around each system, and submitted to periodic simulations where the excess positive charge was neutralized with an equivalent number of chloride anions in monoprotonated systems corresponding to pH 5. Upon gradual heating from 0 K, MD simulations were performed at 300 K for a period of 300 ns

Access to cyclopropanes with geminal trifluoromethyl and difluoromethylphosphonate groups

• Ita Hajdin,
• Romana Pajkert,
• Mira Keßler,
• Jianlin Han,
• Haibo Mei and
• Gerd-Volker Röschenthaler

Beilstein J. Org. Chem. 2023, 19, 541–549, doi:10.3762/bjoc.19.39

• ortho and meta-positions on the phenyl ring (6e, 6f, 6h, 6i), decelerated the process. In the case of α-methylstyrene, complete conversion of diazo reagent 5 to compound 6b was observed only after 48 hours of heating, which might result from the steric hindrance around the reaction centre. In almost all

• olefins with different aliphatic chains. The total conversion of the diazo compound 5 was achieved after 2.5–3.5 hours of heating and the corresponding cyclopropanes 7a–g were obtained in moderate to good yield (28–53%). The highest yield (53%) as well as the best diastereoselectivity were recorded for

Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• File 1). Only the reactions corresponding to the reaction of 1a and 1b show barriers close to 20 kcal/mol thus being plausible to work at ambient temperature or under some heating, which is consistent with the fact that the formation of these adducts were experimentally observed to happen with good

• the reagent the higher is the barrier (for similar transition-state energies) justifying the observed reactivity. Only the two systems (a and b) with lower values of the integration parameter have barriers compatible with observed reactions upon heating, the rest presenting too high barriers to allow

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• (heating rate 6 °C/min), injector temperature 300 °C, detector temperature 300 °C, carrier gas He (99.9999% purity), injected sample volume 2 µL, delay time 4 min. The MS conditions were: energy source EI 70 eV, temperature 150 °C, scan range 50–300 amu, scan rate 1/s. RI values were determined using a C8

• a Netzsch 204 F1 Phoenix apparatus (both from Netzsch Group, Selb, Germany). The TG–DTG and DSC conditions were similar: temperature program of 25–500 °C, with a heating rate of 10 °C/min, nitrogen purge and protection flow of 40 mL/min, the data acquisition and handling by Netzsch Proteus-Thermal

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

An efficient metal-free and catalyst-free C–S/C–O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

• Shubham Sharma,
• Dharmender Singh,
• Sunit Kumar,
• Vaishali,
• Rahul Jamra,
• Naveen Banyal,
• Deepika,
• Chandi C. Malakar and
• Virender Singh

Beilstein J. Org. Chem. 2023, 19, 231–244, doi:10.3762/bjoc.19.22

• amounts of β-cyclodextrin (β-CD) [81] under aqueous conditions at room temperature as well as under heating at 100 °C (entries 1 and 2, Table 1). Unfortunately, the model reactants remained unreacted and similar observations were recorded using a mixture of H2O/MeOH 1:4, and methanol as a reaction medium

• reaction under heating conditions at 70 °C, afforded the desired product 1C in 82% yield with a drastic reduction in the reaction time to 1 hour (entry 16, Table 1). Moreover, an increase in the amount of base had a negligible effect on the yield of the thioamide conjugate 1C (entries 17 and 18, Table 1

• reaction with 5.0 equiv of H2O2 in DMSO as the reaction medium under heating, whereas, a poor yield of the product was obtained (entry 8, Table 2). Moreover, different combinations of H2O2 and DMSO were examined for the oxidative amidation of pyrazole-3-carbaldehyde 1 (entries 9 and 10, Table 2

Investigation of cationic ring-opening polymerization of 2-oxazolines in the “green” solvent dihydrolevoglucosenone

• Solomiia Borova and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2023, 19, 217–230, doi:10.3762/bjoc.19.21

• from 25 °C to 900 °C with a 10 K/min heating rate and the mass loss measured. The resulting data were evaluated with the NETZSCH Proteus – Thermal Analysis – V.5.2.1 software. Dynamic scanning calorimetry (DSC) was performed on a DSC 204F1 Phoenix (NETZSCH, Selb, Germany) under a N2 atmosphere (20.0 mL

• /min). Samples were placed in aluminum pans, heated up to 200 °C and then cooled to −50 °C (10 K/min). The heating/cooling was repeated two additional times. The resulting thermograms were analyzed with the NETZSCH Proteus – Thermal Analysis – V.5.2.1 software. The polymerization of 2-alkyl-2

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• ., by heating with sulphur, to the blue azulene derivative 62 (Scheme 16C) [121][122][124][125][126], but the structure elucidation of this compound was only completed in 1936 [127]. Based on a comparison of IR spectra of natural terpenes, their hydrogenation and dehydrogenation products, the correct