The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• crystals (Figure 5) reached a plateau at 160 °C after 5.9% of the mass was removed as water. The plateau was maintained until 340 °C, when the sample underwent an endothermic decomposition. The decomposition produced sulfur dioxide, naphthalene, and aniline, according to the infrared spectra of the

Synthesis of esters of diaminotruxillic bis-amino acids by Pd-mediated photocycloaddition of analogs of the Kaede protein chromophore

• Esteban P. Urriolabeitia,
• Pablo Sánchez,
• Alexandra Pop,
• Cristian Silvestru,
• Eduardo Laga,
• Ana I. Jiménez and
• Carlos Cativiela

Beilstein J. Org. Chem. 2020, 16, 1111–1123, doi:10.3762/bjoc.16.98

• -position of the aryl rings bonded to carbons C2 and C4 of the cyclobutane. Alkoxycarbonylation is a well-known reaction in Pd(II) chemistry [63][64][65][66]. Therefore, treatment of solutions of cyclobutanes 4 in a mixture of MeOH/NCMe (1:3) with CO (1 atm) at room temperature proceeded with decomposition

• rings of the cyclobutanes (at C2 and C4) probably resulted in a strong steric hindrance around the already crowded cyclobutane ring, which gave rise to instability and decomposition. However, it is remarkable that all functional groups present in the starting materials 4 (C–F, C–Cl, C–NO2, C–CF3 and –C

• few cases some evidence of decomposition (presence of black Pd0) was observed. This was removed by filtration through a bed of Celite®. The resulting clear solution was evaporated to dryness to afford the corresponding ortho-palladated cyclobutanes 4 as deep yellow solids. Characterization of ortho

Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties

• Nuray Altinolcek,
• Ahmet Battal,
• Mustafa Tavasli,
• William J. Peveler,
• Holly A. Yu and
• Peter J. Skabara

Beilstein J. Org. Chem. 2020, 16, 1066–1074, doi:10.3762/bjoc.16.93

• thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC). For TGA, compounds 7a and 7b were heated at 20 °C/min under nitrogen atmosphere. The decomposition temperatures (Td5%) corresponding to 5% weight losses for 7a and 7b were 291 °C and 307 °C, respectively. For DSC, compounds 7a and 7b were

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• with LiBH4 resulted in alcohol 124 which was oxidized by Dess–Martin periodinane to give (S)-(−)-2-fluoro-2-phenylacetaldehyde (125). This aldehyde is prone to racemization and decomposition and therefore was directly converted to the arylidene derivative 127, by treatment with p-toluenesulfinamide

• additional fluorination, decomposition, and consequently low yields of the β-fluorinated derivatives 148 were observed [73] (Scheme 35). 2.8. Fluorination of aziridinium derivatives The N,N-dibenzylated 3-fluorophenylalanine derivative 151 was prepared with excellent diastereoisomeric ratio (dr > 99:1) from

Suzuki–Miyaura cross coupling is not an informative reaction to demonstrate the performance of new solvents

• James Sherwood

Beilstein J. Org. Chem. 2020, 16, 1001–1005, doi:10.3762/bjoc.16.89

• , caution is advised in the presence of nucleophilic reagents, as this has previously been reported to cause ring opening of propylene carbonate during Suzuki–Miyaura cross couplings [7]. In this work no decomposition of propylene carbonate was identified. Using only water as a solvent is also appealing

Accelerating fragment-based library generation by coupling high-performance photoreactors with benchtop analysis

• Quentin Lefebvre,
• Christophe Salomé and
• Thomas C. Fessard

Beilstein J. Org. Chem. 2020, 16, 982–988, doi:10.3762/bjoc.16.87

• electrochemically-mediated nickel-catalyzed cross-couplings. Electron-deficient aniline products are less prone to oxidative decomposition. BCP-amines were viable coupling partners but gave the corresponding products 1a–e in poor purities. Simple azetidines partook the reaction to give 2a–c while azaspiro[3,3

• potential of the arylated product and promote oxidative decomposition. Several spirocyclic compounds with larger ring sizes could be coupled to 3-bromopyridine to give products 4c, 4d, 5a and 5b, provided that steric hindrance was not too high (see 5c). Surprisingly, oxetanes appear to be incompatible with

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• thermal decomposition of urea at 550 °C for 2 h afforded the CN polymer, which possesses abundant –NH2 functional groups. The heterogeneous photocatalyst carbon nitride-hemin (CNH) was prepared after an amidation reaction between a carboxyl group of Fe(III) protoporphyrin IX and an amino group of the CN

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• three possible dissociation pathways that can be followed (Scheme 5). Moreover, Reilly and co-workers observed the decomposition of benzaldehyde (8) into benzene (21) and carbon monoxide (22) (reaction (3) in Scheme 5) after the irradiation at 258.9 nm via laser ionization mass spectrometry and

• , were also found to be compatible. 23 W CFL bulbs were used as the light source for the excitation of benzaldehyde. (NH4)2S2O8 (116) was used as the radical initiator. Photoexcited benzaldehyde (8) enhanced the (NH4)2S2O8 (116) decomposition, accompanied by the generation of the sulfate radical 123

• (116), indicating the necessity of the benzaldehyde (8)-mediated decomposition of (NH4)2S2O8 (116) to generate carbamoyl radicals 125. Varying the light wavelength, the authors observed that it was the near-UV region that was required for the reaction. There was no ground state association observed

Preparation of 2-phospholene oxides by the isomerization of 3-phospholene oxides

• Péter Bagi,
• Réka Herbay,
• Nikolett Péczka,
• Zoltán Mucsi,
• István Timári and
• György Keglevich

Beilstein J. Org. Chem. 2020, 16, 818–832, doi:10.3762/bjoc.16.75

• to decomposition caused by the vigorous reaction conditions. Based on this promising preliminary result with MeSO3H, the effect of both the reaction temperature and the reaction time was investigated. It was found that complete isomerization to the 2-phospholene oxide derivative 4a could not be

• the series of 3-phospholene oxides investigated, ethyl derivative 4h was somewhat the exception, as the yield of the crude product was only 55%, which contained 92% of desired 2-phospholene derivative 4h. This may be the consequence of a higher degree of decomposition occurring in case of this

• Supporting Information File 1 for the results). Whereas the decomposition of the starting material was observed, when phenyl-3-phospholene oxide 1a was treated with n-butyllithium or NaH, as it was also observed by Stankevič et. al. [68] However, when phenyl-3-phospholene oxide was heated in the presence of

Photocatalytic deaminative benzylation and alkylation of tetrahydroisoquinolines with N-alkylpyrydinium salts

• David Schönbauer,
• Carlo Sambiagio,
• Timothy Noël and
• Michael Schnürch

Beilstein J. Org. Chem. 2020, 16, 809–817, doi:10.3762/bjoc.16.74

• obtained with [Ru(bpy)3]Cl2, albeit the reaction was still low-yielding (29%, Table 1, entry 1) and was accompanied with substantial decomposition of the starting material. Eosin Y, fluorescein, and [Ir(dtbbpy)(ppy)2]PF6 gave lower yields in comparison (Table 1, entries 2, 3 and 4). Applying strictly inert

• conditions did not improve the yield, but decomposition of 1 was significantly reduced (Table 1, entry 5). Next, a solvent screening (Table 1, entries 6–12) was performed, showing that reactions in DMSO, DMA, DMF, or DMA/ACN 1:1 improved the yield to >50%, with mass balances of 78–91%. DCE and DCM had no

• decomposition of the reaction components (Figure 1). Then, the substrate scope of the transformation was investigated, reacting different benzylic pyridinium salts with N-phenyl-THIQ (1, Scheme 2). Initially, steric effects were investigated using ortho, meta, and para-methylated benzylpyridinium salts. The

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• alcohol due to decomposition. Nonetheless, several products could be transformed into molecules of greater complexity. For example, cyclopropanation could be achieved to give 269. Additionally, TBS protection of 268 followed by ring closing metathesis (RCM) led to the interesting 6-membered silacycle 270

Microwave-assisted efficient and facile synthesis of tetramic acid derivatives via a one-pot post-Ugi cascade reaction

• Yong Li,
• Zheng Huang,
• Jia Xu,
• Yong Ding,
• Dian-Yong Tang,
• Jie Lei,
• Hong-yu Li,
• Zhong-Zhu Chen and
• Zhi-Gang Xu

Beilstein J. Org. Chem. 2020, 16, 663–669, doi:10.3762/bjoc.16.63

• obtained in the highest yield of 85%. However, at 140 °C, the yield dropped to 72%, probably due to decomposition of the product. When we used an traditional oil bath to heat the mixture for 10 min, only a trace amount of compound 7a was detected by LC–MS (Table 1, entry 16). Compared with Table 1, entry

Copper-catalyzed O-alkenylation of phosphonates

• Nuria Vázquez-Galiñanes,
• Mariña Andón-Rodríguez,
• Patricia Gómez-Roibás and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2020, 16, 611–615, doi:10.3762/bjoc.16.56

• , entry 9). The structure of the alkenyliodonium salt also plays an important role in the outcome of the reaction since the use of a phenyl group instead of the mesityl ligand caused a dramatic decrease in conversion and reaction yield likely due to a faster decomposition of the salt (Table 1, entry 10

• triflic acid via decomposition of ethyl triflate. As a limitation, substrates bearing a vinyl substituent or an enolizable ester group did not give any conversion. This methodology is also applicable to other dialkyl phosphonates as illustrated by the synthesis of enol phosphonates 3j, 3k and 3l

• observed when alkenyliodonium salts bearing aliphatic substituents were used likely due to a faster decomposition of the salt [36][37]. Conclusion In summary, we have developed an efficient copper-catalyzed oxygen alkenylation of dialkyl phosphonates with alkenyl(aryl)iodonium salts. The reaction proceeds

Preparation and in situ use of unstable N-alkyl α-diazo-γ-butyrolactams in Rh^II-catalyzed X–H insertion reactions

• Maria Eremeyeva,
• Daniil Zhukovsky,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2020, 16, 607–610, doi:10.3762/bjoc.16.55

• led to decomposition of the diazo compounds 4a–c), and addition of an alcohol, a thiol, or an aromatic amine along with a RhII catalyst resulted in a rapid insertion reaction and the isolation of the desired α-substituted γ-lactams 7a–o in modest yields (Scheme 1). It should be noted that, after some

Synthesis of 4-amino-5-fluoropyrimidines and 5-amino-4-fluoropyrazoles from a β-fluoroenolate salt

• Tobias Lucas,
• Jule-Philipp Dietz and
• Till Opatz

Beilstein J. Org. Chem. 2020, 16, 445–450, doi:10.3762/bjoc.16.41

• ) of potassium formate, which could not easily be removed without risking the decomposition of the enolate salt (Scheme 1). As the fluorine atom is part of a building block, harsh conditions for a late-stage fluorination can be avoided, and even products with sensitive functionalities are accessible

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• case of [PF6]–-salts while no issues have been reported for the aluminate [6]. The oxidized intermediate PA+• (Equation 7) forms the conjugate acid by decomposition of this instable intermediate resulting in nucleophilic photoproducts inhibiting ring opening polymerization mechanism where carbocations

• photopolymerization with cyanine as sensitizers combined with 88 as PF6−-salt. Exposure with a high power NIR LED emitting at 805 nm initiated cationic photopolymerization of the epoxide Epikote 357, Figure 3. Decomposition of the oxidized sensitizer/oxidized photoactive compound PA+• (Equation 7) provided the

p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

• Panagiotis S. Gritzapis,
• Panayiotis C. Varras,
• Nikolaos-Panagiotis Andreou,
• Katerina R. Katsani,
• Konstantinos Dafnopoulos,
• George Psomas,
• Zisis V. Peitsinis,
• Alexandros E. Koumbis and
• Konstantina C. Fylaktakidou

Beilstein J. Org. Chem. 2020, 16, 337–350, doi:10.3762/bjoc.16.33

• under reflux were identical, meaning that no isomerization or decomposition occurred and that the delivered product in both cases is the more thermodynamically stable. Interestingly, although carbamates are important in both medicinal and polymer chemistry, besides compound 23 [61], all the rest were

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

• Clément Ghiazza and
• Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

• , which is in line with an SN2 mechanism. The authors proposed a mechanism where difluorocarbene is first generated upon thermal decomposition of the starting difluorophosphobetaine. The carbene then reacts with elemental selenium to yield difluoroselenophosgene, and in the presence of fluoride anions

Ultrasonic-assisted unusual four-component synthesis of 7-azolylamino-4,5,6,7-tetrahydroazolo[1,5-a]pyrimidines

• Yana I. Sakhno,
• Maryna V. Murlykina,
• Oleksandr I. Zbruyev,
• Anton V. Kozyryev,
• Svetlana V. Shishkina,
• Dmytro Sysoiev,
• Vladimir I. Musatov,
• Sergey M. Desenko and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2020, 16, 281–289, doi:10.3762/bjoc.16.27

• remained stable under refluxing in acetic acid for 60 min, while heating for 120–180 min led to its decomposition. At the same time, compound 4b, after refluxing in acetic acid for ca. 120 min, was converted into 3-cyano-7-(4-methoxyphenyl)-4,7-dihydropyrazolo[1,5-a]pyrimidine-5-carboxylic acid (7, yield

• the presence of two isomers of 4. The 1H NMR and 13C NMR spectra of triazolyl derivatives 4p–u were more complicated, both due to the duplication of the signals and the fast decomposition of the compounds 4p–u in solutions. Therefore, 2D NMR and, in some cases, 13C NMR spectra were overcrowded and

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

• Itamar L. Gonçalves,
• Rafaela R. da Rosa,
• Vera L. Eifler-Lima and
• Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

• dissimilar moieties, such as alkyloxybenzoic acids [31] and alkylbenzoic and dodecane dicarboxylic acids [32]. The thioureas, with a perfluorinated chain, 17b and 18b, presented thermal decomposition according to the DSC graphs, at temperatures above 200 °C. These compounds were not analyzed by termal

Efficient method for propargylation of aldehydes promoted by allenylboron compounds under microwave irradiation

• Jucleiton J. R. Freitas,
• Queila P. S. B. Freitas,
• Silvia R. C. P. Andrade,
• Juliano C. R. Freitas,
• Roberta A. Oliveira and
• Paulo H. Menezes

Beilstein J. Org. Chem. 2020, 16, 168–174, doi:10.3762/bjoc.16.19

• lower yields or the decomposition of the boron reagent 1 (Table 1, entries 3 and 4). It is worth to note that when the reaction was carried out with conventional heating (100 °C), the desired product was not observed after 1 h. A similar behavior was previously observed by Schaus [32]. Next, the

The interaction between cucurbit[8]uril and baicalein and the effect on baicalein properties

• Xiaodong Zhang,
• Jun Xie,
• Zhiling Xu,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 71–77, doi:10.3762/bjoc.16.9

• ]. At the same concentration of BALE and the Q[8]–BALE complex, the free BALE absorption value, after 6 h, decreased by 0.1 or less (Figure 7) and the decomposition curve equation was A = 0.4730 – 0.0003t. However, the UV absorption intensity of the inclusion complex remained basically unchanged, very

• stable and the decomposition curve equation was A = 0.4353 − 0.00004t. Therefore, the stability of the BALE–Q[8] inclusion complex in the same solvent was 7.5 times higher than that of BALE. Solubilization studies Solubilization studies were performed according to [41]. When compared with the unbound

Microwave-assisted synthesis of 2-substituted 4,5,6,7-tetrahydro-1,3-thiazepines from 4-aminobutanol

• María C. Mollo,
• Natalia B. Kilimciler,
• Juan A. Bisceglia and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2020, 16, 32–38, doi:10.3762/bjoc.16.5

• equivalent 0.5:1 maintained the yield (95%) and considerably simplified the procedure, suppressing collateral products arising from decomposition of the reagent. Under these conditions, compounds 2a–m were synthesized in excellent yields (Table 1). Cleavage of the thioamide-ester 2a with K2CO3 in methanol

Functionalization of the imidazo[1,2-a]pyridine ring in α-phosphonoacrylates and α-phosphonopropionates via microwave-assisted Mizoroki–Heck reaction

• Damian Kusy,
• Agata Wojciechowska,
• Joanna Małolepsza and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 15–21, doi:10.3762/bjoc.16.3

• reaction, because higher temperatures led to decomposition of the reagents (Table 1, entries 6 and 7), and full conversion into the product was not achieved at lower temperatures (Table 1, entry 2). The use of other ligands resulted in a decreased yield (for tri-tert-butylphosphine, (P(t-Bu)3) or DABCO

• , which led to 91% yield (Table 1, entry 22). The shorter exposure to microwave heating probably limited the decomposition of the substrate and the product. Among the various choices of solvents, propionitrile (PCN) delivered the highest amount of product 3, while other solvents led to lower yields (Table

Extension of the 5-alkynyluridine side chain via C–C-bond formation in modified organometallic nucleosides using the Nicholas reaction

• Renata Kaczmarek,
• Dariusz Korczyński,
• James R. Green and
• Roman Dembinski

Beilstein J. Org. Chem. 2020, 16, 1–8, doi:10.3762/bjoc.16.1

• nucleophile present was in slight excess relative to that of the Lewis acid, whereas limited amounts of nucleophile resulted in greater amounts of decomposition. Slightly more decomposition products were observed by TLC in reactions with ribo nucleoside 5 (Table 1, entries 4–7) than with 2'-deoxy derivative 4