[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• involved in C60 reactions with diazo compounds is much wider. In addition, the high yield of the target products and the nearly unlimited variability of substituents in the cyclopropane moiety should be noted as advantages of the latter method. Nevertheless, a drawback that all the [2 + 1] cycloaddition

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• -hydroxyglutarate (84) in a Mitsunobu reaction to generate the γ-phosphonodepsipeptide 79 in a high yield of 66% (Scheme 27) [28]. Synthesis of phosphonodepsipeptides via the multicomponent condensation of amides, aldehydes, and phosphites followed by alcoholysis with hydroxy esters Previously, the Mannich-type

Helicene synthesis by Brønsted acid-catalyzed cycloaromatization in HFIP [(CF₃)₂CHOH]

• Takeshi Fujita,
• Noriaki Shoji,
• Nao Yoshikawa and
• Junji Ichikawa

Beilstein J. Org. Chem. 2021, 17, 396–403, doi:10.3762/bjoc.17.35

• % yield. Similarly, C-shaped double helical helicene 5b was obtained in high yield using m-dibromobenzene 6b with two acetal moieties, prepared from m-xylene (Scheme 5b). We also achieved the synthesis of heterohelicenes, which involve heteroatoms in the helicene frameworks, via a Suzuki–Miyaura coupling

Coupling biocatalysis with high-energy flow reactions for the synthesis of carbamates and β-amino acid derivatives

• Alexander Leslie,
• Thomas S. Moody,
• Megan Smyth,
• Scott Wharry and
• Marcus Baumann

Beilstein J. Org. Chem. 2021, 17, 379–384, doi:10.3762/bjoc.17.33

• resulting telescoped flow process was effectively applied across a series of acid substrates rendering the desired carbamate structures in high yield and purity. The derivatization of these products via complementary flow-based Michael addition reactions furthermore demonstrated the creation of β-amino acid

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

• compounds 161 in high yield (Scheme 40, top). The reaction of CF3-substituted 1,3-diketones 165a–d in TfOH was also deeply investigated by Klumpp et al. [101]. The syn-indanes 166a–d could cleanly be generated after successive well-defined arylation reactions via 167 (Scheme 40, bottom). Moreover, the CF3

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

• in a high yield of 94%. Accordingly, the synthesis of the chromogenic ferulate 12 was achieved in 32% overall yield in 3 steps from commercial reactants (convergent synthesis using a slight excess of the synthesized vinyl ferulate 2) and without the requirement to perform a final deprotection. As

Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic dienes

• Savva A. Ponomarev,
• Roman V. Larkovich,
• Alexander S. Aldoshin,
• Andrey A. Tabolin,
• Sema L. Ioffe,
• Jonathan Groß,
• Till Opatz and
• Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2021, 17, 283–292, doi:10.3762/bjoc.17.27

• straightforward way to novel fluorinated norbornadienes from β-fluoro-β-nitrostyrenes and CPD. Conclusion In summary, the Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclic 1,3-dienes was investigated. A series of novel monofluorinated norbornenes was prepared in high yield up to 97%. A number of novel

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

• manner to give the corresponding 1,3-dithiole derivatives in a high yield. On the other hand, the fact that treatment of 4 with NaH(hfac) and CS2 does not result in substitution of chlorine atoms at the quinone backbone indicates that under such conditions the gem-dithiolate species is not formed

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

• alkenes with the CF3SiMe3–NaI system has been studied (Table 2). Difluorocarbene addition to α-fluorostyrenes enabled the efficient synthesis of trifluorocyclopropanes 34 [41]. The difluorocyclopropanation of protected cyclohexenone yielded cyclopropane 35 [42]. Difluorocyclopropane 36 was formed in high

• yield from the α-bromopyridine-substituted N-Boc-3,4-dehydropiperidine. When the same reaction was attempted on the bromine-free analog, the yield was only 22% [43]. The difluorocyclopropanation of an alkenyl trifluoroborate using the TMSCF3–NaI system afforded the boronate derivative 37 [44]. The

Selective synthesis of α-organylthio esters and α-organylthio ketones from β-keto esters and sodium S-organyl sulfurothioates under basic conditions

• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Thiago Barcellos,
• Claudio C. Silveira and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2021, 17, 234–244, doi:10.3762/bjoc.17.24

• conditions to obtain ethyl 2-(benzylthio)acetate (3a) selectively and in a high yield in hand (Table 1, entry 22), we turned our attention to find an ideal protocol to synthesize 4a. When 0.5 mmol of 1a and 1 mmol of 2a were used in the presence of 2 equivalents of NaOH under air, compound 4a was obtained in

Novel library synthesis of 3,4-disubstituted pyridin-2(1H)-ones via cleavage of pyridine-2-oxy-7-azabenzotriazole ethers under ionic hydrogenation conditions at room temperature

• Romain Pierre,
• Anne Brethon,
• Sylvain A. Jacques,
• Aurélie Blond,
• Sandrine Chambon,
• Sandrine Talano,
• Catherine Raffin,
• Branislav Musicki,
• Claire Bouix-Peter,
• Loic Tomas,
• Gilles Ouvry,
• Rémy Morgentin,
• Laurent F. Hennequin and
• Craig S. Harris

Beilstein J. Org. Chem. 2021, 17, 156–165, doi:10.3762/bjoc.17.16

• ((cis)-3-aminocyclobutyl)carbamate afforded the undesired regioisomer 28 as the majority product (Scheme 5). As we were unable to exploit intermediate 26, we turned our attention to the pyridine-2-(1H)-one building block 30, easily prepared by hydrolysis of the C-2–F bond in high yield and without the

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• + and crown ether, leading to the formation of cyclobutane in a high yield. D’Souza et al. constructed a photosynthetic triad 4 to mimic the photosynthetic reaction center [19]. A BODIPY, an ammonium-functionalized fullerene, and a zinc porphyrin functioned as the energy donor, electron acceptor, and

Facile preparation and conversion of 4,4,4-trifluorobut-2-yn-1-ones to aromatic and heteroaromatic compounds

• Takashi Yamazaki,
• Yoh Nakajima,
• Minato Iida and
• Tomoko Kawasaki-Takasuka

Beilstein J. Org. Chem. 2021, 17, 132–138, doi:10.3762/bjoc.17.14

• was also performed (Table 3). First of all, 3aa was introduced to a t-BuOH solution of 2 equiv of t-BuOK to afford the desired product 4aa in a high yield, and an increase in the amount of this base to 3 equiv led to the complete conversion of the substrate 3aa (Table 3, entries 3 and 4). This trend

• outlined above, the results of which are summarized in Table 6. When the reactions were performed with acetamidine and guanidine, a good to high yield was recorded, while only a lower yield was obtained by the application of formamidine acetate, for which the reaction was not further elucidated at this

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

• (−)-79a and (−)-79b, which were oxidized to enone (−)-80. The enone (−)-80 was subjected to ring-closing metathesis with Grubbs second-generation catalyst resulting in cyclic enone (−)-81 in 74% yield. (−)-81 was treated with phenylselenol to generate selenide 82 in high yield. The ozonolysis of 82 was

Amine–borane complex-initiated SF₅Cl radical addition on alkenes and alkynes

• Audrey Gilbert,
• Pauline Langowski,
• Marine Delgado,
• Laurent Chabaud,
• Mathieu Pucheault and
• Jean-François Paquin

Beilstein J. Org. Chem. 2020, 16, 3069–3077, doi:10.3762/bjoc.16.256

• sterically hindered DICAB, compared to the liquid DIPAB, but that a too high reaction temperature such as 60 °C tends to increase the degradation pathways instead of the formation of the desired compound. However, this effect was not observed when performing the reaction in MTBE. A high yield of 86% was

Deoxyfluorination of acyl fluorides to trifluoromethyl compounds by FLUOLEAD^®/Olah’s reagent under solvent-free conditions

• Yumeng Liang,
• Akihito Taya,
• Zhengyu Zhao,
• Norimichi Saito and
• Norio Shibata

Beilstein J. Org. Chem. 2020, 16, 3052–3058, doi:10.3762/bjoc.16.254

• afforded the desired products smoothly in good to high yield in solvent-free conditions. An extension of this deoxyfluorination strategy to drug-like molecules was demonstrated to show the usefulness of this transformation. The present protocol also expands the utility of FLUOLEAD® in organic synthesis

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• isoindigos to give an enantioenriched annulation adduct bearing vicinal quaternary stereocenters [46] (Scheme 7A). Both symmetric and unsymmetric isoindigos can undergo enantioselective [3 + 2] annulation with an allene and produced a chiral adduct with high yield and high ee value. When unsymmetric

Three-component reactions of aromatic amines, 1,3-dicarbonyl compounds, and α-bromoacetaldehyde acetal to access N-(hetero)aryl-4,5-unsubstituted pyrroles

• Wenbo Huang,
• Kaimei Wang,
• Ping Liu,
• Minghao Li,
• Shaoyong Ke and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2920–2928, doi:10.3762/bjoc.16.241

• to access the insect-growth regulators [44]. It is noteworthy that the sulfonamide group persisted during this transformation, and the desired pyrrole product 4r could be obtained in 69% yield. A high yield was also obtained when the phenyl group was replaced with a naphthyl group in 4s. Subsequently

One-pot multicomponent green Hantzsch synthesis of 1,2-dihydropyridine derivatives with antiproliferative activity

• Giovanna Bosica,
• Kaylie Demanuele,
• José M. Padrón and
• Adrián Puerta

Beilstein J. Org. Chem. 2020, 16, 2862–2869, doi:10.3762/bjoc.16.235

• to be successful; the reaction requires strong acids. In addition, a peculiar result was obtained when analyzing the structure of the product obtained since the less frequently reported regioisomer, the unsymmetrical 1,2-DHP, was being obtained in a high yield and with a high selectivity. At this

Changed reactivity of secondary hydroxy groups in C8-modified adenosine – lessons learned from silylation

• Jennifer Frommer and
• Sabine Müller

Beilstein J. Org. Chem. 2020, 16, 2854–2861, doi:10.3762/bjoc.16.234

• , the evaluation of a fast and high yield synthetic route for obtaining the modified ribonucleoside building block is highly desirable. For this reason, we have redesigned the synthesis strategy, and decided to use di-tert-butylsilyl bis(trifluoromethanesulfonate) as reagent for 3’,5’-di-O-protection of

Dirhamnolipid ester – formation of reverse wormlike micelles in a binary (primerless) system

• David Liese,
• Hans Henning Wenk,
• Xin Lu,
• Jochen Kleinen and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2020, 16, 2820–2830, doi:10.3762/bjoc.16.232

• chain length without the production of side products (Scheme 1). Under mild and basic conditions, with this SN2 reaction of the dirhamnolipid and any primary alkyl halide, the desired product was obtained with a high yield ranging from 70–85%. Also, a gemini-like structure 7 was synthesized. Solubility

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• in a high yield and enantioselectivity (Scheme 5) [17][18]. The Rubottom oxidation [28] of 43 gave a separable mixture of the desired 44 and its C-14 epimer (≈7:1 ratio). The reductive deoxygenation of 44 proceeded via the tosylhydrazone to afford 45, which upon desilylation and alkyne isomerization

• . Unfortunately, all attempted 1,4-reduction conditions afforded an inseparable mixture of trans-54 as the major product along with minor amounts of the desired cis-55. Alternatively, the asymmetric reduction of the 2-acylfuran 56 using the Corey–Bakshi–Shibata reagent (21) [30] gave the alcohol 57 in a high

• yield and high enantioselectivity (Scheme 7) [15][16]. The Achmatowicz oxidation and ionic reduction generated the enone 58, which is regioisomeric with 53. The 1,4-addition of lithium dimethylcopper gave the desired cis-55 with high a diastereoselectivity (25:1). The cross-metathesis of 55 with 3

Synergy between supported ionic liquid-like phases and immobilized palladium N-heterocyclic carbene–phosphine complexes for the Negishi reaction under flow conditions

• Edgar Peris,
• Raúl Porcar,
• María Macia,
• Jesús Alcázar,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2020, 16, 1924–1935, doi:10.3762/bjoc.16.159

• are depicted in Figure 3. As expected, the use of a larger residence time led to a high yield. Quantitative yields were initially obtained under these conditions, with a productivity of 1.73 g 7/g Pd·h. This level of activity was kept constant during at least 5.5 h of continuous use. However, after

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• , entries 2–8) under ultrasound irradiation at 45–50 °C. From this study, it was observed that the NDL (2.5 wt %) was the best option, which gave the target compound 3a in a high yield (85%) in a mixture of EtOH and H2O 1:1 under ultrasound irradiation for 30 min at 45–50 °C (Table 2, entry 5). The other

One-pot synthesis of isosorbide from cellulose or lignocellulosic biomass: a challenge?

• Isaline Bonnin,
• Raphaël Mereau,
• Thierry Tassaing and
• Karine De Oliveira Vigier

Beilstein J. Org. Chem. 2020, 16, 1713–1721, doi:10.3762/bjoc.16.143

• wheat straw pulp led to 63% of isosorbide, corresponding to a productivity of 40 g·L−1·h−1 with 72% of purity. This high yield can be ascribed to several parameters such as small particle diameter, large surface area/porosity and lower crystallinity. For the particle size, cellulose fiber diameters are