Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• ]chromeno[2,3-h]quinoxalinoporphyrins 3–8. For the optimization of the reaction conditions, a model four-component reaction of copper(II) 2,3-diamino-5,10,15,20-tetra(p-tolyl)porphyrin with 2-hydroxynaphthalene-1,4-dione (2), benzaldehyde and dimedone was carried out in the presence of 20 mol % p

• ]chromeno[2,3-h]quinoxalinoporphyrin 3. Optimization of the reaction conditions for the synthesis of copper(II) benzo[f]chromeno[2,3-h]quinoxalinoporphyrin 3.a Supporting Information Supporting Information File 186: Characterization data, 1H and 13C NMR spectra of newly prepared porphyrin products

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• of simpler chemical systems with less components and less factors to optimize per reactor. This would require less re-optimization of existing chemistry. Recyclable donors could be stored in tanks like RFB electrolytes, which decouples the 2 reactions and means rates do not have to be perfectly

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

• compounds 4a–i, 9a, and 10a in EtOH. Methods for the synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones. One-pot synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones 4a–i, 9a, and 10a. Optimization of reaction conditionsa. Data of absorption and fluorescence spectra of compounds 4a–i, 9a, and 10a.a Supporting

Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light

• Damiano Diprima,
• Hannes Gemoets,
• Stefano Bonciolini and
• Koen Van Aken

Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82

• of CH3CN/H2O 8:2 (v:v). b2 equiv toluene as an additive. c1 equiv LiCl as an additive. dProduct not isolated, GC-FID conversion. Setup used in the flow experiment for the triphenylphosphine oxidation. Proposed extra alternative pathway. Optimization experiments of thioanisole oxidation.a Effect of

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Linker, loading, and reaction scale influence automated glycan assembly

• Marlene C. S. Dal Colle,
• Manuel G. Ricardo,
• Nives Hribernik,
• José Danglad-Flores,
• Peter H. Seeberger and
• Martina Delbianco

Beilstein J. Org. Chem. 2023, 19, 1015–1020, doi:10.3762/bjoc.19.77

• , but isolated in relatively low yields. The optimization procedures are focused on glycan elongation (i.e., glycosylation and deprotection steps), whereas less attention is given to variables associated with the solid support [17]. In contrast, substantial knowledge exists on how loading [18], reaction

Copper-catalyzed N-arylation of amines with aryliodonium ylides in water

• Kasturi U. Nabar,
• Bhalchandra M. Bhanage and
• Sudam G. Dawande

Beilstein J. Org. Chem. 2023, 19, 1008–1014, doi:10.3762/bjoc.19.76

• ) with iodonium ylide 2-(phenyl-λ3-iodaneylidene)cyclohexane-1,3-dione (2a) obtained from 1,3-cyclohexanedione in the presence of copper salts as catalysts. The detailed optimization studies are described in Table 1. Initially, we treated aniline (1a, 0.2 mmol) with iodonium ylide 2a (0.24 mmol) in the

• iodine reagents. N-Arylation of primary amines with iodonium ylide. Reaction conditions: 0.2 mmol aniline 1, 0.24 mmol iodonium ylide 2, CuSO4·5H2O (10 mol %), water (2 mL). N-Arylation of secondary amines with iodonium ylide. Optimization of reaction conditionsa. Supporting Information Supporting

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

• . Reactivity of tetrahydrofuro[3,2-c]pyridine 4a. Optimization of reaction conditionsa. Supporting Information Supporting Information File 47: Experimental procedures, characterization data, copies of 1H and 13C NMR spectra, HRMS of new compounds, and X-ray crystallography data. Supporting Information File 48

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

• . Many zinc catalysts (Zn(OTf)2, Et2Zn, ZnI2, Zn powder, anhydrous ZnCl2, Zn(NO3)2⋅6H2O, ZnSO4⋅H2O, Zn(OAc)2⋅2H2O and ZnO), reaction temperature, time, and catalyst loading was screened for the optimization. After optimizations, 5 mol % Zn(OTf)2 as catalyst, reaction time for 8 h, and temperature of 70

• conditions in 90–96% yields (method 2). The optimization of the reaction conditions was performed in search of suitable conditions for this condensation reaction. Various acid catalysts (SiO2, HPA, HPA/SiO2, catalyst loadings (1 mol %, 2 mol %, 2.5 mol %, 0.3 g), solvent-systems (petroleum ether 40/60

Asymmetric tandem conjugate addition and reaction with carbocations on acylimidazole Michael acceptors

• Brigita Mudráková,
• Renata Marcia de Figueiredo,
• Jean-Marc Campagne and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 881–888, doi:10.3762/bjoc.19.65

• time led to the formation of only one diastereomer, but in a low yield of 11%. Neither the addition of LiCl helped to increase the diastereoselectivity of the reaction (Table 1, entry 8). See Supporting Information File 1, for complete optimization of the reaction conditions. Achieving

• scope. Results of selected optimization experiments. Supporting Information Supporting Information File 174: Characterization data for all compounds, computational details, and picture of NMR spectra. Funding This work was supported by the Slovak Research and Development Agency under the Contract no

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• of pyridine at the C2 and C3 position (Scheme 35a). Further, during optimization when silver additives like Ag2CO3, Ag2O, and AgOAc were used the reaction resulted in the formation of isoquinoline derivative 181. In addition, the reaction showed high regioselectivity in the presence of unsymmetrical

Facile access to 3-sulfonylquinolines via Knoevenagel condensation/aza-Wittig reaction cascade involving ortho-azidobenzaldehydes and β-ketosulfonamides and sulfones

• Ksenia Malkova,
• Andrey Bubyrev,
• Stanislav Kalinin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 800–807, doi:10.3762/bjoc.19.60

• -substituted quinolines. Synthetic routes to sulfonamides and sulfones 2 and the set of reagents for the preparation of compounds 5. Preparation of 3-sulfonyl substituted quinolines 5a–q. 3-Sulfonyl-substituted quinolines 5r–v that failed to be synthesized. Optimization of reaction conditions.a Supporting

Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Mikhail E. Minyaev and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58

• -bottomed glass flask. Synthesis of photoproducts 12. Reaction conditions: method A) 10 (0.5 mmol), DMF (15 mL) irradiation for 48 h; method B) 1) 9 (0.5 mmol), DMF (15 mL), irradiation for 96 h; 2) CDI (1.75 mmol, 0.28 g), MeCN (5 mL), reflux, 2 h. Optimization of the condensation conditions.a Ratio of

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

• used as an additive along with the oxidant K2S2O8 in MeCN, the desired product N-benzenesulfonylimine 2a was obtained in 90% yield (Table 1, entry 3). Subsequently, we carried out further optimization studies by changing the additive, solvent, temperature, and reaction time to obtain the best possible

• -pot synthesis of N-heterocycles. Optimization of reaction conditions.a Supporting Information Supporting Information File 112: General procedures, product characterization, and copies of 1H NMR and 13C NMR spectra of all compounds. Acknowledgements The authors acknowledge NIPER S.A.S. Nagar for

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

• high potential for further optimization. Aerobic oxidation using transition metals instead of TEMPO was also investigated. Pd(OAc)2 (Table 1, entry 6) [42] and Cu(OAc)2 (Table 1, entry 7) [43], and Ni(OH)2 (Table 1, entry 8) [44] left the starting material 1a. Pd(OAc)2 led to moderate conversion, but

• for low-cost and environmentally friendly aerobic oxidation and further optimized it to improve the reaction rate. Reaction optimization for aerobic oxidation under batch conditions Based on entry 3 in Table 1, we next focused on optimizing the reaction to increase the reaction rate (Table 2). Open

• aerobic oxidation using the honeycomb reactor. Flow setup for substrate scope and additional screening. Reaction screening for aerobic oxidation of 4-methoxybenzyl alcohol (1a). Reaction optimization for aerobic oxidation of 4-methoxybenzyl alcohol (1a). Evaluation of the reaction rate using various flow

Palladium-catalyzed enantioselective three-component synthesis of α-arylglycine derivatives from glyoxylic acid, sulfonamides and aryltrifluoroborates

• Bastian Jakob,
• Nico Schneider,
• Luca Gengenbach and
• Georg Manolikakes

Beilstein J. Org. Chem. 2023, 19, 719–726, doi:10.3762/bjoc.19.52

• to our previous study with the corresponding boronic acids [22]). Synthesis of both enantiomers of arylglycine building block 18. Reaction optimization. Supporting Information Supporting Information File 176: Experimental section and characterization data. Funding Financial support by the research

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

• Deepak Singh,
• Shyamal Pramanik and
• Soumitra Maity

Beilstein J. Org. Chem. 2023, 19, 666–673, doi:10.3762/bjoc.19.48

• triple role as activator of IPs, halide scavenger, and acetylating agent. Results and Discussion Optimization In the quest for the optimal reaction conditions, we started our investigations with 2-phenylimidazo[1,2-a]pyridine (1a) and diethyl bromomalonate (2a) as model substrates. Initially, the

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

• HPLC-UV yield of compound 3aa. These conditions were taken as a standard for further reactions. Noteworthy, we had to derivatize product 3aa to detect it by HPLC–UV during the optimization studies. For these purposes, compound 3aa was converted to compound 4 by an earlier procedure developed by us

• (Scheme 12) by an earlier procedure developed by us [51] in order to investigate the reaction optimization by HPLC–UV. Then, the reactant scope of the reaction was explored by involving to the reaction APBTTs 1a–h, bearing various aroyl substituents, and benzylamine (Scheme 13) [55]. As a result, we found

• us [51] in order to investigate the reaction optimization by HPLC-UV. After that, the reactant scope of the reaction was explored by involving to the reaction APBTTs 1a–h, bearing various aroyl substituents, and arylamines 11a–d, bearing aryl substituents with various electronic effects (Scheme 18

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

• (Scheme 1b). Results and Discussion First optimization with a home-made pulsed-flow setup We undertook the optimization of this flow strategy for the C3-alkylation reaction (Murai reaction) [37][38] of the furfurylimine 1 bearing a removable N,N'-bidentate directing group. In a previous study, this

• reactions for this first optimization were performed using a home-made setup based on an HPLC apparatus (Jasco) equipped with an injection valve (Rheodyne) comprising a 105 μL loop into which the reaction mixture is loaded and then pushed by the solvent delivered by the HPLC pump (see Supporting Information

• Information File 1 for the reaction kinetic curves of catalysts). In addition, the catalyst with a single L1 ligand (comp1) was found to be more reactive than the one with two ligands (comp2), and was therefore selected for further optimization. In contrast, comparison of its reaction kinetic curve with that

Direct C2–H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

• Martina Mamone,
• Giuseppe Gentile,
• Jacopo Dosso,
• Maurizio Prato and
• Giacomo Filippini

Beilstein J. Org. Chem. 2023, 19, 575–581, doi:10.3762/bjoc.19.42

• with the α-iodosulfone 2a in the presence of DABCO. Study of scope of the HAS reaction between indoles 1 and α-iodosulfones 2. Yields in parentheses were determined by 1H NMR analyses, using 1,3,5-trimethoxybenzene as an internal standard. Optimization of the reaction conditions and control experiments

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

• –vis spectra corresponding to isolated conjugates in the aqueous solution. For that purpose, we used the most abundant structure of each system in Figure 2 and performed the geometry optimization by the M06-2X DFT approach [53] together with the 6–31+G(d) basis set [54] in the Gaussian 16 program

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

• then involved in the next catalytic cycle and thus removed from the equilibrium between Int4 and Pr + CuI. In addition, since TS2 is an early transition state and the potential is concomitantly very flat, only TS2_2 was found by means of regular optimization towards a first order saddle point. For the

• Int2 yielding Int4_3 and Int4_4 without further intermediates. Formation of the products Pr1 to Pr4. Optimization of the reaction conditionsa. Change in Gibbs free energy ΔG (kcal∙mol−1) from the CuI-catalyzed cyclopropanation of the diazo compound with styrene for possible stereoisomers Pr1 to Pr4

Synthesis and reactivity of azole-based iodazinium salts

• Thomas J. Kuczmera,
• Annalena Dietz,
• Andreas Boelke and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27

• under preservation of the hypervalent iodine center. Optimization of reaction conditions for the synthesis of azoiodazinium salts 5aa and 5ah.a Supporting Information Supporting Information File 154: Experimental procedures, characterization data and copies of spectra. Acknowledgements Dr. Marian

Recommendations for performing measurements of apparent equilibrium constants of enzyme-catalyzed reactions and for reporting the results of these measurements

• Robert N. Goldberg,
• Robert T. Giessmann,
• Peter J. Halling,
• Carsten Kettner and
• Hans V. Westerhoff

Beilstein J. Org. Chem. 2023, 19, 303–316, doi:10.3762/bjoc.19.26

• concentrations of species in complex reaction mixtures at equilibrium. Thus, values of K and K′ are used to determine the practicality of using a reaction to manufacture a substance and for process optimization in bioengineering applications. These values can also be used in the analysis of the kinetics of

Continuous flow synthesis of 6-monoamino-6-monodeoxy-β-cyclodextrin

• János Máté Orosz,
• Dóra Ujj,
• Petr Kasal,
• Gábor Benkovics and
• Erika Bálint

Beilstein J. Org. Chem. 2023, 19, 294–302, doi:10.3762/bjoc.19.25

• and reduction. All reaction steps were studied separately and optimized under continuous flow conditions. After the optimization, the reaction steps were coupled in a semi-continuous flow system, since a solvent exchange had to be performed after the tosylation. However, the azidation and the

• easier process than the optimization of a new monosubstitution reaction on a native CD [5]. Monotosylation of the primary rim of CDs is the most widely used method to obtain C-6 monofunctionalized CDs. Tosyl chloride (TsCl) reacts with α-, β-, and γ-CD in pyridine to give the C-6-monosubstituted product

• 1 mL/min input flow was used while conducting the hydrogenations during the optimization, which resulted in approximately a 20 second residence time in all cases. A complete conversion was observed using even the mildest conditions possible (25 °C, 1 bar H2 pressure) in aqueous solution (Table 3