A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• complex (ʟ-proline-MCM-41-CuCl) was obtained by the reaction of ʟ-proline-MCM-41 with CuCl in acetone at mild temperature (Scheme 21) [51]. A possible mechanism for this reaction is shown in Scheme 22. Initially, copper(I)-substituted acetylide intermediate 70 is produced via the reaction of copper

Breaking paracyclophane: the unexpected formation of non-symmetric disubstituted nitro[2.2]metaparacyclophanes

• Suraj Patel,
• Tyson N. Dais,
• Paul G. Plieger and
• Gareth J. Rowlands

Beilstein J. Org. Chem. 2021, 17, 1518–1526, doi:10.3762/bjoc.17.109

• , 143.4, 137.0, 132.1, 131.0, 129.9, 129.3, 129.1, 69.6, 42.9, 34.5, 33.1, 31.1; 1H NMR (700 MHz, acetone-d6) δ (ppm) 7.45 (d, J = 7.9 Hz, 1H, H-13), 7.15 (dd, J = 1.6, 7.7 Hz, 1H, H-12), 6.70 (dd, J = 1.6, 7.7 Hz, 1H, H-15), 6.56 (dd, J = 1.7, 7.7 Hz, 1H, H-16), 6.47 (dd, J = 2.9, 10.0 Hz, 1H, H-5), 5.87

• , acetone-d6) δ (ppm) 186.8, 147.0, 146.6, 143.1, 137.7, 130.7, 130.0, 198.8, 194.4, 128.3, 128.3, 68.6, 43.2, 34.1, 32.8, 30.8; HRMS-EI m/z: [M + Na]+ calcd for C16H16O2Na, 263.1043; found, 263.1054; ESIMS (m/z): [M]+ 241, 224, 118, 104; IR: 3386, 2918, 2849, 1651, 1622, 1261, 1020, 829, 813 cm−1; mp: 206

Total synthesis of ent-pavettamine

• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2021, 17, 1440–1446, doi:10.3762/bjoc.17.99

• that the new route doubled the overall yield to 16% for a similar number of steps. The specific optical rotation for 4 of +28.1° in acetone was comparable to that obtained previously [1]. Single crystal X-ray analysis of compound 4 (Figure 3), further confirmed the identity and stereochemistry of the

• compound 9. Stereoselective reduction of intermediate 8 as key step towards intermediate 4. Reaction conditions: a) i) ZnCl2, rt, 2 h; ii) DIBALH, THF, −78 °C to rt, 2 h, 87%; b) TBAF, THF, 0 °C, 4 h, 87%; c) 5% p-TsOH, 2,2-dimethoxypropane, acetone, rt, 1 h, 86%. Synthesis of the C5 fragments from

Analogs of the carotane antibiotic fulvoferruginin from submerged cultures of a Thai Marasmius sp.

• Birthe Sandargo,
• Leon Kaysan,
• Rémy B. Teponno,
• Christian Richter,
• Benjarong Thongbai,
• Frank Surup and
• Marc Stadler

Beilstein J. Org. Chem. 2021, 17, 1385–1391, doi:10.3762/bjoc.17.97

• filtered and the supernatant extracted with 2% AmberliteTM XAD 16N (Rohm & Haas, Frankfurt a. M., Germany), subsequently resuspended in acetone and evaporated to dryness, resulting in 2.5 g of crude extract. This supernatant crude extract was filtered using a SPME StrataTM-X 33 u Polymeric RP cartridge

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• reported procedure [35]. l-Indanone (1, 6.8 g, 51.4 mmol) was added to a mixture of 60 mL acetic acid and 30 mL concentrated HCl, then the reaction mixture was stirred for 16 h at 100 °C. The solid precipitate was obtained by pouring the reaction mixture into crushed ice, washing with water, acetone

• with CH2Cl2, acetone, and finally with ethyl acetate to give 11 (3.13 g, 92%) as a yellow solid. Synthesis of 2,7,12-tribromo-5,5,10,10,15,15-hexabutyl-10,15-dihydro-5H-diindeno[1,2-a:1',2'-c]fluorene (5): Compound 11 (1.5 g, 2.59 mmol), dimethyl sulfoxide (20 mL), and potassium tert-butoxide (2.61 g

Icilio Guareschi and his amazing “1897 reaction”

• Gian Cesare Tron,
• Alberto Minassi,
• Giovanni Sorba,
• Mara Fausone and
• Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

• reported in 1874 and was synthesized by refluxing of a saturated solution of ammonia in acetone, but the structure of this trimer had not yet been established [39]. Guareschi obtained triacetonamine in high yield (>70%) by treatment of phorone (7), the trimer of acetone, with ammonia and established the

• Guareschi” [42]. Triacetonamine bears a certain similarity to tropinone (9), the heterocyclic core of tropane alkaloids, and the one-pot preparation from acetone and ammonia reminds of, and anticipates by two decades, the Robinson synthesis of tropinone and the Willstätter synthesis of the corresponding 2

• Zentralblatt summary. Additionally, ambiguities exist on the molecularity of the various reactions since Guareschi was often preparing β-aminocarbonyl derivatives in situ from the self-condensation of acetone and the aza-Michael trapping of mesityl oxide. This method works well only for acetone, while further

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

• Cansu Esen and
• Baris Kumru

Beilstein J. Org. Chem. 2021, 17, 1323–1334, doi:10.3762/bjoc.17.92

• mL acetone to remove the remaining vTA, then left in a fume hood for drying overnight. Pore substructuring of HGCM by photoinitiation: 100 mg as-prepared HGCM and certain amounts of patching monomer (consisting 10 mol % crosslinker) were added into a capped glass vial containing 2 g distilled water

A new glance at the chemosphere of macroalgal–bacterial interactions: In situ profiling of metabolites in symbiosis by mass spectrometry

• Marine Vallet,
• Filip Kaftan,
• Veit Grabe,
• Fatemeh Ghaderiardakani,
• Simona Fenizia,
• Aleš Svatoš,
• Georg Pohnert and
• Thomas Wichard

Beilstein J. Org. Chem. 2021, 17, 1313–1322, doi:10.3762/bjoc.17.91

• , 4 μL of ectoine at concentration 50 μM was pipetted onto a clean glass slide (washed with dH2O, acetone) and overlaid with 2 μL of a methanolic solution of the DHB matrix at a concentration of 4 mg mL−1. For a bacterial isolate, the sample was prepared from one colony smeared onto a glass slide and

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• flow reacting acetone with a wide range of aldehydes. In batch, acetone-based aldol reactions are typically performed under biphasic conditions by slow addition of the aldehyde to an acetone/NaOH mixture kept at low temperatures. Upon scale-up, this carries with it problems such as inefficient mixing

• , difficulty in maintaining the reaction temperature and the occurrence of greater amounts of acetone and aldehyde self-condensation/polymerisation. By adopting a flow protocol and using a Comet X-01 micromixer (with linear scalability), more efficient mixing was attained and less aldehyde self-condensation

• was evident (Scheme 3). Within the microreactor acetone was first deprotonated by merging with a 2.5 M sodium hydroxide stream at room temperature, then, after a residence time of just 45 seconds, the resultant enolate was introduced to a stream containing the aldehyde as a 5.5 M solution also in

Synthesis of multiply fluorinated N-acetyl-D-glucosamine and D-galactosamine analogs via the corresponding deoxyfluorinated glucosazide and galactosazide phenyl thioglycosides

• Vojtěch Hamala,
• Lucie Červenková Šťastná,
• Martin Kurfiřt,
• Petra Cuřínová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2021, 17, 1086–1095, doi:10.3762/bjoc.17.85

• configuration. Thioglycosides 22–31, 34 and 36 were then hydrolyzed into the corresponding hemiacetals 37–48 using treatment with NBS in acetone/water (Scheme 4). To obtain the target fluoro analogs, the hemiacetals 37–48 were debenzylated and their azide group converted to an acetamide. Although palladium

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• . At first, they tested in situ-generated complexes of L14 and Pd(TFA)2 in methanol or acetone, but the reduction to catalytically inactive Pd(0) occurred faster. The reoxidation by Cu(BF4)2·6H2O led to the loss of enantioselectivity presumably because of the complexation of the bisoxazoline by Cu(II

Synthesis of β-triazolylenones via metal-free desulfonylative alkylation of N-tosyl-1,2,3-triazoles

• Soumyaranjan Pati,
• Renata G. Almeida,
• Eufrânio N. da Silva Júnior and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2021, 17, 762–770, doi:10.3762/bjoc.17.66

• in the yield, the reaction was carried out in different solvents such as THF, EtOAc, toluene, DCM, 1,2-DCE, 2-MeTHF, isopropanol and acetone. Unfortunately, these attempts led to inferior results (Table 1, entries 5–12). Since, there was no further improvement in the yield, the conditions described

Total synthesis of pyrrolo[2,3-c]quinoline alkaloid: trigonoine B

• Takashi Nishiyama,
• Erina Hamada,
• Daishi Ishii,
• Yuuto Kihara,
• Nanase Choshi,
• Natsumi Nakanishi,
• Mari Murakami,
• Kimiko Taninaka,
• Noriyuki Hatae and
• Tominari Choshi

Beilstein J. Org. Chem. 2021, 17, 730–736, doi:10.3762/bjoc.17.62

• oxidation of tetrahydroquinoline 31 was examined. Following the evaluation of various reaction conditions [32][33][34], the best outcome was obtained upon treatment of 31 with KMnO4 and MgSO4 in an acetone–H2O solvent system [35]. Employing these conditions, trigonoine B (1) was obtained in 43% yield. The

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

Designed whole-cell-catalysis-assisted synthesis of 9,11-secosterols

• Marek Kõllo,
• Marje Kasari,
• Villu Kasari,
• Tõnis Pehk,
• Ivar Järving,
• Margus Lopp,
• Arvi Jõers and
• Tõnis Kanger

Beilstein J. Org. Chem. 2021, 17, 581–588, doi:10.3762/bjoc.17.52

• until further analysis. Synthesis of substrates 11β-Hydroxyandrost-4-ene-3,17-dione (2) To a stirred solution of cortisol (1, 1.2 g, 3.36 mmol) in a 1:1 mixture of EtOH and CH2Cl2 (23 mL), NaBH4 (51.2 mg, 1.35 mmol) was added in one portion at room temperature. After 2 h, acetone (5.8 mL) was added

• . The residue was chromatographed on silica gel with gradient 10% to 40% acetone in petroleum ether to give acetate 3 (213.2 mg, 93%) as pale yellow oil. [α]D20 +180.0 (c 0.58, CHCl3); 1H NMR (CDCl3, 400 MHz) δ 5.68 (d, J = 1.4 Hz, 1H), 5.47 (q, J = 3.1 Hz, 1H), 2.57–2.21 (m, 6H), 2.20–2.05 (m, 4H

• ) was added, after which this was mixed and extracted with EtOAc (5 mL). The organic layer was dried over magnesium sulfate, filtered and concentrated in vacuo. The residue was chromatographed on silica gel with gradient 7% to 30% acetone in petroleum ether to give monoacetate 3 (151 mg, 52%) and

Amino- and polyaminophthalazin-1(2H)-ones: synthesis, coordination properties, and biological activity

• Zbigniew Malinowski,
• Emilia Fornal,
• Agata Sumara,
• Renata Kontek,
• Karol Bukowski,
• Beata Pasternak,
• Dariusz Sroczyński,
• Joachim Kusz,
• Magdalena Małecka and
• Monika Nowak

Beilstein J. Org. Chem. 2021, 17, 558–568, doi:10.3762/bjoc.17.50

• = Me, 85%; 3b R1 = iPr, 84%) were obtained by the direct alkylation of bromophthalazinone 2 with methyl or isopropyl iodide in the presence of K2CO3 in dry acetone as the solvent (conventional heating). In the similar way also the 2-aminoethyl lactams 3c (R1 = CH2CH2NMe2) and 3d (R1 = CH2CH2(morpholin

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

• Lucía Rossi-Fernández,
• Viviana Dorn and
• Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

• lithium. The resulting solid was filtered under vacuum in a Büchner funnel and washed successively with water (10 mL) and acetone (10 mL). Finally, the solid was dried under vacuum (5 Torr). Catalytic test – typical procedure for olefin epoxidation To a vigorously stirred suspension of the CoNPs/MgO

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• allylic triflates 18 and 19, showing a significant solvolysis retardation with CF3-substituted substrates (Figure 3) [46]. These results are in accordance with an earlier study that revealed that 20 was unreactive in acetone/H2O 70:30, even over a period of 35 days at 50 °C [47]. Encouraged by these

• be observed in the case of a displacement–elimination mechanism. Promising results were first obtained during investigations conducted on CF3-substituted derivatives in SN1- and SN2-mechanism-based reactions (Scheme 23). A profound retardation effect for the solvolysis of 81 in acetone–H2O (SN1) with

Synthesis of legonmycins A and B, C(7a)-hydroxylated bacterial pyrrolizidines

• Wilfred J. M. Lewis,
• David M. Shaw and
• Jeremy Robertson

Beilstein J. Org. Chem. 2021, 17, 334–342, doi:10.3762/bjoc.17.31

• was subjected to a third round of chromatography (toluene/ethyl acetate 3:2 → toluene/ethyl acetate/acetone 2:2:1) to afford the title compound as an oil (661 mg, 47%). Rf 0.35 (dichloromethane/methanol 9:1); 1H NMR (400 MHz, CD3OD) δ 1.02 (d, J = 6.5 Hz, 3H), 1.03 (d, J = 6.5 Hz, 3H), 1.59 (s, 3H

• of water with toluene (2 × 50 mL). The residue was purified by column chromatography (toluene/ethyl acetate/acetone 3:2:0–12:8:5) to afford the title compound as a yellow amorphous solid (345 mg, 56% corrected for the presence of ≈10 wt % toluene). The data are consistent with literature values [22

• ]. Rf 0.10 (toluene/ethyl acetate/acetone 2:2:1); mp 128 °C [lit. mp not given]; IR νmax 3234br, 2958m, 1667m, 1571s, 1517s, 1437s, 1197m, 730m; 1H NMR (400 MHz, CD3OD) δ 1.01 (d, J = 6.5 Hz, 3H), 1.02 (d, J = 6.5 Hz, 3H), 1.58 (s, 3H), 1.65 (ddd, J = 13.0, 10.5, 7.5 Hz, 1H), 1.93 (ddd, J = 13.0, 6.5

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• g, reusable) was added to a solution of alcohol (0.30 mmol, 1 equiv) and the vinyl ferulate 2 (100 mg, 0.45 mmol, 1.5 equiv) in acetonitrile (6 mL). The reaction mixture was stirred overnight at 37 °C, then filtered, the filter cake was washed with acetone, and the filtrate was evaporated to dryness

• equiv) in acetone/water 2.5–1, v/v (3.5 mL) was treated at 25 °C under stirring with NMMO (106 mg, 0.90 mmol, 1.2 equiv) and osmium tetroxide (2.5 wt % solution in tert-butanol, 38 µL) and stirred at room temperature for 18 h. 10% (w/v) aqueous sodium sulfite (0.5 mL) was added, and stirring was

Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands

• Sergey V. Norkov,
• Anton V. Cherkasov,
• Andrey S. Shavyrin,
• Maxim V. Arsenyev,
• Viacheslav A. Kuropatov and
• Vladimir K. Cherkasov

Beilstein J. Org. Chem. 2021, 17, 273–282, doi:10.3762/bjoc.17.26

• -2-thione species 6a in a high yield (Scheme 1, route 2). The red color of the reaction mixture belonging to the parent o-quinone rapidly turns into a brown color of o-quinone 6a. o-Quinone 6a was isolated as red-brown crystals by cooling the acetone/ether mixture. It is a structural analogue of o

• was discussed previously [29]. The reaction of 4 with malononitrile-derived gem-dithiolate (5b, Scheme 1, route 2) also proceeded under mild conditions in DMF and bicyclic o-quinone 6b was obtained in a good yield. The brown crystals suitable for X-ray analysis were grown from an acetone/diethyl ether

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• )-monoacetate (S)-80, respectively (Scheme 32). As for the transesterification, a high yield (96.5%) and enantioselectivity (91.3% ee) were obtained using lipase PS in benzene. In the case of the deacetylation, the use of Amano PS lipase in acetone gave a high yield (86.2%), enantioselectivity (91.7% ee), and

Total synthesis of decarboxyaltenusin

• Lucas Warmuth,
• Aaron Weiß,
• Marco Reinhardt,
• Anna Meschkov,
• Ute Schepers and
• Joachim Podlech

Beilstein J. Org. Chem. 2021, 17, 224–228, doi:10.3762/bjoc.17.22

• . Biphenyl-derived mycotoxins. Synthesis of arylboronates 6. Conditions: a) TBSCl, DMAP, imidazole, DMF, 50 °C, 4 h (96%); b) NBS, MeCN, rt, 71 h (quant.); c) NBS, MeCN, rt, 72 h (R = TBS, 96%); d) BnBr, KI, K2CO3, DMF/acetone, 70 °C, 29 h, (R = Bn, 86%); e) R = TBS: BuLi, 2-isopropoxy-4,4,5,5-tetramethyl

• , K2CO3, DMF/acetone 1:2, 80 °C, 43 h (98%). Final steps in the synthesis of biaryl 1. Conditions: h) Pd(OAc)2, SPhos, Cs2CO3, dioxane/H2O 7:1, 70 °C, 18 h, (R = TBS: 98%, containing non-separable impurities; R = Bn: 89%) ; i) R = Bn: Pd/C (10%), H2, THF, 8 bar, 24 h, 40 °C (88%). NMR data of natural and

A sustainable strategy for the straightforward preparation of 2H-azirines and highly functionalized NH-aziridines from vinyl azides using a single solvent flow-batch approach

• Michael Andresini,
• Leonardo Degannaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2021, 17, 203–209, doi:10.3762/bjoc.17.20

• functionalized oxazoles using acetone as the solvent (Scheme 1c) [28]. Inspired by these recent reports, we became interested in the development of an eco-friendly strategy for the safe preparation of highly functionalized NH-aziridines from acyclic precursors. Herein, we report a sustainable mixed flow-batch

• flow procedures involved acetonitrile, dichloromethane and acetone as solvents, however, incompatible with the utilization of reactive alkali organometals. An exception is made for toluene, used by Kirschning for the photoinduced azirine formation [27]. Therefore, we investigated the thermally induced

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

• Dimas J. P. Lima,
• Antonio E. G. Santana,
• Michael A. Birkett and
• Ricardo S. Porto

Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4

• ) PCC, CH2Cl2, 70–72%. Synthesis (+)-euphococcinine (2). Reagents and conditions: i) H2O2, SeO2 (cat), acetone, rt, 88%; ii) 25, THF, −78 °C, 52% (67:33 diastereomeric mixture); iii) H2O2, FIEt+.ClO4 (cat.), MeOH, 0 °C, 55%; iv) AlCl3, CH2=CHCH2MgBr, THF, −78 °C, 54%; v) Ni2O3, CHCl3, rt, 54%; vi) Raney

• acetal, cat. (CH2OH)2, BF3·Et2O, 85%; x) 1. Luche reduction, 98%; 2. a) NaH; b) CS2, c) MeI, 88%; 3. Bu3SnH, AIBN, heat, 75%; xi) 1. cat. Pd(MeCN)2Cl2, wet acetone, 95%; 2. H2, Pd-C, 90%. Synthesis of (+)-euphococcinine (2). Reagents and conditions: i) 1. Cp2ZrCl2,AlMe3, CH2Cl2; 2. p-menthyl-3