Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• adduct with 18 that was readily separable from the target ketones. Following the optimization of reaction conditions, a change of solvent to THF was shown to be as equally effective as toluene (Table 1, entry 10). The ketones S-9, S-10, and S-11 were obtained in a ratio of 1:6.9:5.2, indicating a higher

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• ) and the dimethylacetal derived from chloroacetaldehyde 11 affords the dithiolane 12. This 1,3-dithiolane spontaneously rearranges to the 1,4-dithiane with an elimination of hydrochloric acid by refluxing in a mixture of water and toluene. This two-step procedure constitutes a scalable and simple

Practical synthesis of isocoumarins via Rh(III)-catalyzed C–H activation/annulation cascade

• Qian-Ci Gao,
• Yi-Fei Li,
• Jun Xuan and
• Xiao-Qiang Hu

Beilstein J. Org. Chem. 2023, 19, 100–106, doi:10.3762/bjoc.19.10

• to be the optimal solvent, while other commonly used solvents such as toluene, dioxane, and ethanol gave inferior yields (Table 1, entries 2–4, 14–39%). Further screening of bases did not improve the outcome of the product, whereas 63% yield of 3aa was obtained when acetic acid was added into the

Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• refluxing toluene was reported to proceed with retention of configuration to afford the β-epimer 6 [16]. Another nice application of this chemistry was recently reported by Oestreich and co-workers, who converted 3β-hydroxypregn-5-en-20-one into the corresponding 3-bromo derivative, which also occurred with

Two-step continuous-flow synthesis of 6-membered cyclic iodonium salts via anodic oxidation

• Julian Spils,
• Thomas Wirth and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 27–32, doi:10.3762/bjoc.19.2

• decomposition of the intermediary iodoarene. Here it was possible to perform the procedure with either benzene or toluene, leading to a moderate yield of 38% and 37%. We could not use derivatives with any other substituents with secondary benzyl acetates since those led only to inseparable product mixtures

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• [3.2.1]octane 67 was achieved by a radical cyclization using n-Bu3SnH in refluxing toluene. A sequence involving an ester reduction, Ley–Griffith oxidation and Seyferth–Gilbert homologation with Bestmann–Ohira reagent allowed to obtain the alkynyl bicylo[3.2.1]octane 69. On the other hand, the five

A novel spirocyclic scaffold accessed via tandem Claisen rearrangement/intramolecular oxa-Michael addition

• Anastasia Vepreva,
• Alexander Yanovich,
• Dmitry Dar’in,
• Grigory Kantin,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1649–1655, doi:10.3762/bjoc.18.177

• Discussion The initial attempt to involve DAS 1b in the Rh2(esp)2-catalyzed insertion reaction with 4-(tert-butyl)phenol was successful. The initial adduct 5b was not purified and was heated at 140 °C in toluene to give compound 6b in 47% yield over two steps (Scheme 2). No further optimization of the

• from the data collated in Table 1, to our delight, cyclizations of the phenoxide anion generated on the action of base (except for 2,6-lutidine) proceeded as 5-exo-trig (rather than 6-endo-trig) process and yielded spirocyclic compound 7a as a mixture of syn and anti diastereomers. DABCO in toluene at

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• reducing agent sodium bis(2-methoxyethoxy)aluminum hydride (Red-Al®), which is a convenient alternative to LiAlH4 that exhibits high solubility in organic solvents and is also known to reduce amides [17]. When a solution of amide 5 in toluene was treated with an excess of Red-Al® at 0 °C, rapid gas

• compound has also been prepared in racemic form [25]. To supply the final two carbon atoms found in the halichonic acids, amine 4 was condensed with a solution of ethyl glyoxylate in toluene, giving imine 7 in 95% yield. We found that imine 7 could be purified by column chromatography on silica gel if the

A new route for the synthesis of 1-deazaguanine and 1-deazahypoxanthine

• Raphael Bereiter,
• Marco Oberlechner and
• Ronald Micura

Beilstein J. Org. Chem. 2022, 18, 1617–1624, doi:10.3762/bjoc.18.172

• -(tetrahydro-2H-pyran-2-yl)-1-deazapurine (18) Compound 17 (1.72 g, 5.23 mmol), copper(I) iodide (CuI, 99.52 mg, 0.52 mmol), 1,10-phenanthroline (188.35 mg, 1.05 mmol), caesium carbonate (Cs2CO3, 2.38 g, 7.32 mmol) and benzyl alcohol (BnOH, 1.13 g, 1.07 mL, 10.45 mmol) were suspended in 2.62 mL toluene (0.5 mL

• was purified via silica gel chromatography using 0 to 4% methanol in dichloromethane as gradient. Yield: 395 mg of a mixture containing the 2-nitro-compound 20 and 21 (for NMR spectra see Supporting Information File 1). TLC: (5% acetone in toluene): Rf 0.34 (compound 20), Rf 0.05 (compound 21

• alcohol (BnOH, 328.55 mg, 310 µL, 3.04 mmol) were suspended in 0.76 mL of toluene (0.5 mL per 1 mmol compound 17) and stirred for 4 hours at 110 °C under atmospheric conditions. After complete reaction (TLC reaction control), the suspension was allowed to cool to room temperature and the catalyst was

Functionalization of imidazole N-oxide: a recent discovery in organic transformations

• Koustav Singha,
• Imran Habib and
• Mossaraf Hossain

Beilstein J. Org. Chem. 2022, 18, 1575–1588, doi:10.3762/bjoc.18.168

• toluene and acetone (2:1), mixture of chlorobenzene and acetone (2:1), or a mixture of hexachloroacetone and acetone (7:1). Under the optimized conditions, the screening of various polyphenols showed that the yields of products were 70–95% when the mixture of toluene and acetone (2:1) was used as solvent

A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups

• Naser-Abdul Yousefi,
• Morten L. Zimmermann and
• Mikael Bols

Beilstein J. Org. Chem. 2022, 18, 1553–1559, doi:10.3762/bjoc.18.165

• in Table 1. Firstly, reaction with DIBAL in toluene at 0.3 M concentration and at 50 °C gave after 24 h almost complete conversion of the starting material to a symmetrical compound 8 that according to MALDI–TOF MS has lost two DCB groups and not any benzyl group. The compound was analyzed with 1H

• formed from 8. When 7 was reacted with 1.5 M DIBAL in toluene at 60 °C for 24 hours an almost equal amount of 8 and 9 was present (Table 1, entry 3) and 27% of triol 9 together with 32% of 8 was isolated. A tetrol 10 was obtained upon even longer reaction of 7: If reacted with 0.1 M DIBAL in toluene for

• mixture was left to stir overnight, and the reaction was quenched by addition of MeOH (10 mL). The mixture was diluted with toluene, and the organic phase washed with H2SO4 (1 M, 20 mL), then brine (3 × 20 mL), dried (MgSO4), filtered, and concentrated. Column chromatography in a solvent gradient of

Cyclometalated iridium complexes-catalyzed acceptorless dehydrogenative coupling reaction: construction of quinoline derivatives and evaluation of their antimicrobial activities

• Hongling Shui,
• Yuhong Zhong,
• Renshi Luo,
• Zhanyi Zhang,
• Jiuzhong Huang,
• Ping Yang and
• Nianhua Luo

Beilstein J. Org. Chem. 2022, 18, 1507–1517, doi:10.3762/bjoc.18.159

• of 2-aminobenzyl alcohol (1a) with 1-phenylethanol (2a) as model reaction in the presence of various cyclometalated iridium complexes TC-1–TC-6 (Table 1). Encouragingly, employing TC-1 as the catalyst, toluene as the solvent and t-BuOK as the base at 100 °C, quinoline 3aa was obtained in 73% yield

One-pot synthesis of 2-arylated and 2-alkylated benzoxazoles and benzimidazoles based on triphenylbismuth dichloride-promoted desulfurization of thioamides

• Arisu Koyanagi,
• Yuki Murata,
• Shiori Hayakawa,
• Mio Matsumura and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 1479–1487, doi:10.3762/bjoc.18.155

• contrast, THF, toluene, DMF, and DMSO were inefficient reaction solvents (entries 11–14). Thus, 1,2-DCE was the best solvent for the reaction in terms of the product yield of 8a (99%), while chloroform posed a concern of acid contamination. Examination of the optimum amount of reagents 2a and 6a toward 1a

Design, synthesis, and evaluation of chiral thiophosphorus acids as organocatalysts

• Karen R. Winters and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2022, 18, 1471–1478, doi:10.3762/bjoc.18.154

• = Et (2.4 equiv), toluene, 60 °C). Further optimization with the pivalate led to 20 in 82% yield and 68% ee (19 R2 = t-Bu (2 equiv), cyclopentyl methyl ether, 22 °C). To account for the best results observed with pivalate 18, Guinchard and coworkers proposed the transition-state shown in Scheme 5 [31

Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence

• Kaiyue Ye,
• Liyuan Cao,
• Davita M. E. van Raamsdonk,
• Zhijia Wang,
• Jianzhang Zhao,
• Daniel Escudero and
• Denis Jacquemin

Beilstein J. Org. Chem. 2022, 18, 1435–1453, doi:10.3762/bjoc.18.149

• observed (Figure 2c), which is similar to that of NI-PTZ. For NI-Ph-PTZ, a structured fluorescence band was observed in the 400–600 nm range (Figure 2d), which is assigned to LE emission. In toluene, however, a broad emission band centered at 624 nm was observed, which we attribute to the CT emission (with

• the phenyl moiety as donor group). The emission maximum (624 nm) is blue-shifted as compared to that of NI-PTZ (731 nm in toluene), indicating that the CT state energy of NI-Ph-PTZ is higher than that of NI-PTZ [47]. Similar results were observed for NI-PhMe2-PTZ (Supporting Information File 1, Figure

• (468.0 mg, 1.209 mmol), phenothiazine (289.0 mg, 1.452 mmol), Pd(OAc)2 (49.2 mg, 0.219 mmol) and sodium tert-butoxide (760.0 mg, 7.908 mmol) were dissolved in dry toluene (22 mL). Then tri-tert-butylphosphine tetrafluoroborate (66.4 mg, 0.229 mmol) was added. The mixture was refluxed and stirred for 8 h

Preparation of an advanced intermediate for the synthesis of leustroducsins and phoslactomycins by heterocycloaddition

• Anaïs Rousseau,
• Guillaume Vincent and
• Cyrille Kouklovsky

Beilstein J. Org. Chem. 2022, 18, 1385–1395, doi:10.3762/bjoc.18.143

• reaction. However, switching the solvent from THF to toluene afforded 21% of product 23 with CeCl3 as additive. It appeared that the solvent had more influence on the course of the reaction than the metal. Indeed, reaction between vinyl iodide and ketone with n-BuLi in toluene [32] without any additive

• under argon. Acetonitrile, dichloromethane, DMSO, DMF and toluene were distilled over calcium hydride under argon. All other reagents were used as received. Chromatographic purifications refer to flash chromatography on silica gel. 1H NMR spectra were measured at 250, 300, 360 or 400 MHz using CDCl3 as

• -triisopropylsilyloxyhexa-1,3-dien (17): A 0.5 M solution of potassium hexamethyldisilazide in toluene (4.4 mL, 2.22 mmol, 1.2 equiv) was added to a cooled (−78 °C) solution of diethyl chlorophosphate (0.27 mL, 1.85 mmol) in anhydrous THF (7 mL). A solution of the enone 16 (500 mg, 1.85 mmol) in THF (6 mL) was then slowly

Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

• Almaz A. Zagidullin,
• Farida F. Akhmatkhanova,
• Mikhail N. Khrizanforov,
• Robert R. Fayzullin,
• Tatiana P. Gerasimova,
• Ilya A. Bezkishko and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139

• ) was treated in a 1:1 ratio with [FeCp(η6-C6H5CH3)][PF6] at 160 °C in diglyme. Evaporation of diglyme at reduced pressure and extraction of the product with toluene, followed by filtration through silica, resulted in 3,4,5-tris(3-chlorophenyl)-1,2-diphosphaferrocene (8b) in 68% yield and high purity

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

• Merve Karaman,
• Abhishek Kumar Gupta,
• Subeesh Madayanad Suresh,
• Tomas Matulaitis,
• Lorenzo Mardegan,
• Daniel Tordera,
• Henk J. Bolink,
• Sen Wu,
• Stuart Warriner,
• Ifor D. Samuel and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

• -OBuIm and DiKTa-DPA-OBuIm are long at 317 μs and 242 μs, respectively. RISC rate constants, kRISC, were calculated for both emitters, which are 2.85 × 103 s−1 and 3.04 × 103 s−1, respectively for DiKTa-OBuIm and DiKTa-DPA-OBuIm, compared to that of DiKTa (4.6 × 104 s−1) in toluene [27][39]. Light

Modular synthesis of 2-furyl carbinols from 3-benzyldimethylsilylfurfural platforms relying on oxygen-assisted C–Si bond functionalization

• Sebastien Curpanen,
• Per Reichert,
• Gabriele Lupidi,
• Giovanni Poli,
• Julie Oble and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2022, 18, 1256–1263, doi:10.3762/bjoc.18.131

• debenzylation/cyclization of benzyldimethysilyl-substituted allylic alcohols [32]. To that end, carbinol 4c was treated with TBAF⋅3H2O (1.0 equiv), which resulted in the formation of 16 in 86% yield (along with toluene, Scheme 6). Alike 5-membered cyclic dimethyl(alkenyl)siloxanes, 16 was found to be highly

Dienophilic reactivity of 2-phosphaindolizines: a conceptual DFT investigation

• Nosheen Beig,
• Aarti Peswani and
• Raj Kumar Bansal

Beilstein J. Org. Chem. 2022, 18, 1217–1224, doi:10.3762/bjoc.18.127

• -phosphaindolizines having an EWG at the 3-position only, namely 3-ethoxycarbonyl-1-methyl-2-phosphaindolizine (1: R1 = Me, R2 = COOEt) did not undergo the DA reaction with DMB alone or in the presence of sulfur even when refluxing in toluene [12]. The reaction could be accomplished only in the presence of a Lewis

Lewis acid-catalyzed Pudovik reaction–phospha-Brook rearrangement sequence to access phosphoric esters

• Jin Yang,
• Dang-Wei Qian and
• Shang-Dong Yang

Beilstein J. Org. Chem. 2022, 18, 1188–1194, doi:10.3762/bjoc.18.123

• the standard substrates to test the suitable conditions for the O-phosphination product 3aa. Delightfully, in the presence of 10 mol % Cu(OTf)2 in toluene at 100 °C, the desired product 3aa was obtained in 62% yield, and no Pudovik adduct 4aa was detected (Table 1, entry 1). Inspired by this result

Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation

• Ashish Kumar Mazumdar,
• Gyana Prakash Nanda,
• Nisha Yadav,
• Upasana Deori,
• Upasha Acharyya,
• Bahadur Sk and
• Pachaiyappan Rajamalli

Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122

• aggregated state as compared to toluene solution. Consequently, a faster reverse intersystem crossing rate (kRISC) was obtained in the aggregated state, facilitating photon upconversion, leading to enhanced delayed fluorescence. Further, the lone-pair electrons of the pyridinyl nitrogen atom were found to be

• twisted BPy-p3C (Figure S1, Supporting Information File 1) [30]. The steady-state emission of both BPy-pTC and BPy-p3C was recorded in different polar media (Figure 1c and Figure 1d). The BPy-pTC emission lay in the cyan region, and the peak was centered at λem = 476 nm in toluene (Figure 1b). The

• emission spectra of BPy-pTC were red-shifted in polar media, and the emission maxima changed from λem = 476 nm in toluene to λem = 497 nm in THF and to λem = 545 nm in DCM (Figure 1c). Similarly, blue emission was observed in toluene at λem = 488 nm for BPy-p3C, and it red-shifted to λem = 530 nm in THF

Scope of tetrazolo[1,5-a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof

• Laura Holzhauer,
• Chloé Liagre,
• Olaf Fuhr,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2022, 18, 1088–1099, doi:10.3762/bjoc.18.111

• catalyst at 100 °C in dry toluene, using DIPEA as an additional base. The use of DIPEA resulted in faster conversions and slightly higher yields (see Table S1, Supporting Information File 1). In total, 14 novel triazoloquinoxalines could be obtained successfully with yields ranging from 11% to 89%, showing

• prepared by reaction of the ligands with rhenium pentacarbonyl bromide (26) in toluene at 110 °C (see Scheme 6 and Scheme 7) as reported in the literature [12]. The structures of all obtained complexes could be confirmed via single crystal X-ray crystallography, verifying unambiguously the formation of the

• ',1'-c]quinoxaline (24) and conversion to triazoloimidazoquinoxalines (TIQs): 2.5 equiv hexyne, 10 mol % (CuOTf)2·C6H6 (7), toluene, 100 °C, 4 h to 3 d. ORTEP diagram of triazoloimidazoquinoxaline 25b with the thermal ellipsoids shown at 50% probability. Synthesis of rhenium tricarbonyl complexes 27a

Synthesis, optical and electrochemical properties of (D–π)₂-type and (D–π)₂Ph-type fluorescent dyes

• Kosuke Takemura,
• Kazuki Ohira,
• Taiki Higashino,
• Keiichi Imato and
• Yousuke Ooyama

Beilstein J. Org. Chem. 2022, 18, 1047–1054, doi:10.3762/bjoc.18.106

• stannyl D–π unit with 1,3-diiodobenzene, respectively. Their optical and electrochemical properties were investigated by photoabsorption and fluorescence spectroscopy, time-resolved fluorescence spectroscopy, cyclic voltammetry (CV) and molecular orbital (MO) calculations. In toluene the photoabsorption

• orbital (MO) calculations. Results and Discussion Using a toluene solution containing 1,3-diiodobenzene and (diphenylamino)carbazole-thiophenestannane derivative 1 [33] in the presence of Pd(PPh3)4, the (D–π)2-type and (D–π)2Ph-type fluorescent dyes OTK-2 [33] and OTT-2 were obtained by Stille coupling of

• 1 with 1,3-diiodobenzene and oxidative homocoupling of 1, respectively (Scheme 1). The photoabsorption and fluorescence spectra of OTK-2 and OTT-2 in toluene are shown in Figure 1a,b, and their optical data are summarized in Table 1. As shown in insets of Figure 1a,b, the toluene solutions of OTK-2

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 991–998, doi:10.3762/bjoc.18.99

• the product 3a in 65% yield. However, no product 3a was obtained when the reaction was carried out in toluene at room temperature or in acetonitrile at 0 °C. The yield of 3a remained the same when the reaction was carried out at elevated temperature. At last, using of higher loading of TBAB and