Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• allyl alcohol. Stepwise synthesis of 2,6-distubstituted dioxane derivatives. Cyclization of carbohydrate alkene precursor. Hg(II)-mediated synthesis of C-glucopyranosyl derivatives. Synthesis of C-glycosyl amino acid derivative using Hg(TFA)2. Hg(OAc)2-mediated synthesis of α-ᴅ-ribose derivative

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• oxide 1,3-dipolar cycloaddition/ROM/CM strategies was presented. The stepwise functionalization of norbornadiene across the ring olefin bonds generated fluorine-containing alkenylated cyclopentane-fused isoxazolines. The synthetic protocol was based on selective nitrile oxide cycloaddition to the

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• capping step [279] permitted to drastically improve overall yields and to simplify the purification (Figure 6). The 100mer 93 was obtained with a calculated average stepwise yield of 98.75% (Scheme 14). Long α-mannosides have the advantageous feature of being highly soluble due to the high flexibility of

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• -fluoropyridinium salts 5-4 could be synthesized in four different ways using 10% F2/N2 [28][31][33] (Scheme 10): method A (stepwise method) involved the fluorination of a pyridine derivative with F2/N2, to form a pyridine·F2 complex 5-2, followed by treatment with a non-nucleophilic anion salt, acid, or silyl

Fritsch–Buttenberg–Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes

• Tsutomu Kimura,
• Koto Sekiguchi,
• Akane Ando and
• Aki Imafuji

Beilstein J. Org. Chem. 2021, 17, 1352–1359, doi:10.3762/bjoc.17.94

• generated in situ from chloromethyl p-tolyl sulfoxide, diethyl chlorophosphate, and LDA, and the reaction of the HWE reagent with carbonyl compounds gave sulfoxides 2e–g. The 2,2-disubstituted sulfoxides 2b–d, which could not be prepared by the one-pot HWE reaction, were prepared through a stepwise method

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

• β-(2-hydroxyaryl)enones [34]. Synthesis of enantiomerically enriched 1-aryl-1H-indenes [36]. Stepwise addition of arylboronic acids to electron-rich chalcones and Bayer–Villiger oxidation [3]. Synthesis of 4-aryldihydrocoumarins by stepwise 1,4-addition and Bayer–Villiger oxidation [3]. First report

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

Simulating the enzymes of ganglioside biosynthesis with Glycologue

• Andrew G. McDonald and
• Gavin P. Davey

Beilstein J. Org. Chem. 2021, 17, 739–748, doi:10.3762/bjoc.17.64

• negative charge. Figure 1 shows the structure of the monosialylated ganglioside GM1a. The biosynthesis of gangliosides occurs in the endoplasmic reticulum and Golgi, where specific glycosyltransferases act, in stepwise fashion, by adding monosaccharides from sugar nucleotide donors, first to ceramide, and

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

• to decrease in the order Zn > Mn > Co > Cu > Ni, consistent with previous reports [209]. The best catalyst afforded BHET in 84.1% yield (Table 2, entry 9), which was rather constant over eight catalyst reuses [210]. A stepwise depolymerisation mechanism was proposed, via intermediate oligomers, in

Synthesis and physicochemical evaluation of fluorinated lipopeptide precursors of ligands for microbubble targeting

• Masayori Hagimori,
• Estefanía E. Mendoza-Ortega and
• Marie Pierre Krafft

Beilstein J. Org. Chem. 2021, 17, 511–518, doi:10.3762/bjoc.17.45

• structure [30]. These lipopeptides have a discrete molecular weight and are produced by Fmoc (fluorenylmethoxycarbonyl protecting group) SPPS, a procedure in which the peptide chain is assembled stepwise while attached to an insoluble resin support, which allows the easy removal of the byproducts at each

• (SG)5KSS peptide chain is assembled stepwise using a Fmoc solid-phase peptide synthesis procedure. In a second step, the two perfluoroalkylated chains are grafted to the peptide chain through a lysine moiety. Next, the surface activity of the synthesized lipopeptides is investigated by assessing their

Deoxygenative C2-heteroarylation of quinoline N-oxides: facile access to α-triazolylquinolines

• Geetanjali S. Sontakke,
• Rahul K. Shukla and
• Chandra M. R. Volla

Beilstein J. Org. Chem. 2021, 17, 485–493, doi:10.3762/bjoc.17.42

• the stepwise pathway. The plausible mechanism for the C2-triazolylation of quinoline N-oxides is presented in Scheme 7 [64]. The reaction initiates by the nucleophilic attack of quinoline N-oxide, e.g., 1a, on the sulfonyl group of N-sulfonyl-1,2,3-triazole 2, leading to the formation of intermediate

Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement

• Vladimir Kubyshkin,
• Rebecca Davis and
• Nediljko Budisa

Beilstein J. Org. Chem. 2021, 17, 439–460, doi:10.3762/bjoc.17.40

• occurrences), in contrast to most abundant CCG codons (31603 occurrences) [77]. The incorporation of proline into proteins is accomplished by the natural biosynthetic machinery via a complex stepwise process (see steps 3–5 in Figure 8). The initial recognition of any amino acid that participates in protein

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

• of 93%, the Pummerer rearrangement of sulfoxide 214 under harsh conditions turned out to be less efficient, affording 204f in only 42% yield. This reaction is thought to proceed stepwise via a first oxidative electron transfer, followed by deprotonation, a second oxidative electron transfer, and

Hydrazides in the reaction with hydroxypyrrolines: less nucleophilicity – more diversity

• Dmitrii A. Shabalin,
• Evgeniya E. Ivanova,
• Igor A. Ushakov,
• Elena Yu. Schmidt and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2021, 17, 319–324, doi:10.3762/bjoc.17.29

• TFA (Table 1, entry 6) did not significantly promote the 3aa→4aa transformation, that was apparently caused by the deactivation of the acid catalyst by ammonia, released in the preceding step (vide infra for the mechanism discussion). To prevent this process, a stepwise addition of TFA was tested

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

• and CF3 groups are omitted for clarity. Synthetic pathways for the preparation of o-quinone derivatives with annulated 1,3-dithiole ring. The tentative pathway for the formation of o-quinone 7 with annulated thiete ring. Reactions of o-quinone 6a. Stepwise reduction of o-quinones with metals to

Au(III) complexes with tetradentate-cyclam-based ligands

• Ann Christin Reiersølmoen,
• Thomas N. Solvi and
• Anne Fiksdahl

Beilstein J. Org. Chem. 2021, 17, 186–192, doi:10.3762/bjoc.17.18

• Ann Christin Reiersolmoen Thomas N. Solvi Anne Fiksdahl Department of Chemistry, Norwegian University of Science and Technology, Høgskoleringen 5, 7491, Trondheim, Norway 10.3762/bjoc.17.18 Abstract Chiral cyclam (1,4,8,11-tetraazacyclotetradecane) derivatives were synthesized stepwise from

• unsuccessful Au(III) coordination of the diphenyl-C2-bridged 5b ligand, in contrast to the readily coordinating cyclohexyl-bridged 5a tetraamine, as discussed above (Scheme 3). Conclusion A new stepwise procedure was developed for improved preparation of chiral cyclam derivatives 5a,b and 6a,b from chiral mono

Synthesis of aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers through the base-mediated reaction between phenols and halothane

• Yukiko Karuo,
• Ayaka Kametani,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2021, 17, 89–96, doi:10.3762/bjoc.17.9

• reaction mechanism as shown in Scheme 4a. The reaction was carried out in a stepwise procedure in which the phenoxide was prepared by mixing equimolar amounts of phenol (1a) and NaH to consume all NaH in the reaction mixture, and then halothane was added to the reaction mixture. The stepwise reaction gave

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

• reaction; Introduction A multicomponent approach towards the synthesis of the desired product offers a number of advantages over a stepwise method. Such advantages include the development of a design that is: cheaper, simpler, economical, and environmentally friendly [1][2]. Multicomponent reactions are

Nocarimidazoles C and D, antimicrobial alkanoylimidazoles from a coral-derived actinomycete Kocuria sp.: application of ¹J_C,H coupling constants for the unequivocal determination of substituted imidazoles and stereochemical diversity of anteisoalkyl chains in microbial metabolites

• Md. Rokon Ul Karim,
• Enjuro Harunari,
• Amit Raj Sharma,
• Naoya Oku,
• Kazuaki Akasaka,
• Daisuke Urabe,
• Mada Triandala Sibero and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 2719–2727, doi:10.3762/bjoc.16.222

• silica gel column using a mixture solvent of CHCl3/MeOH (1:0, 20:1, 10:1, 4:1, 2:1, 1:1, and 0:1, v/v). Fraction 3 (10:1) was concentrated to yield 0.38 g of a brown oil, which was further fractionated by ODS column chromatography with a stepwise gradient of a MeCN/0.1% HCO2H aqueous solution (2:8, 3:7

A heterobimetallic tetrahedron from a linear platinum(II)-bis(acetylide) metalloligand

• Matthias Hardy,
• Marianne Engeser and
• Arne Lützen

Beilstein J. Org. Chem. 2020, 16, 2701–2708, doi:10.3762/bjoc.16.220

• diameter from the DOSY experiment (dh = 33 Å). Conclusion In summary, we presented the self-assembly of a large decanuclear heterobimetallic tetrahedron that was readily obtained in a stepwise manner. The linear metalloligand 3 facilitated the formation of tetrahedral cages, when combined with pyridine-2

• : red – iron, white – platinum, orange – phosphorous, blue – nitrogen, grey – carbon. Hydrogen atoms are omitted for clarity. The stereogenic centers are defined in the schematic tetrahedra. Stepwise assembly of the heterobimetallic tetrahedron 4, starting from 4-ethynylaniline (1) and trans-[Pt(PBu3

Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity

• Yuvixza Lizarme-Salas,
• Alexandra Daryl Ariawan,
• Ranjala Ratnayake,
• Hendrik Luesch,
• Angela Finch and
• Luke Hunter

Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216

• products. We were forced to conclude that the rather complex structure of 3 was incompatible with the Jacobsen catalytic system. Since the one-step difluorination method (Scheme 1) was unsuccessful, we decided to pursue a stepwise fluorination approach [26][27] (Scheme 2). Thus, the allylic alcohol 7 [28

• geometry of 2 might be favoured in AChE but not in BACE-1. These possibilities all remain speculative in the absence of high-resolution structural data of the enzyme–ligand complexes. Conclusion A threo-difluorinated piperine analog (2) was successfully synthesised through a stepwise route. The

• μM) and 2 (IC50 > 1000 μM). The attempted synthesis of 6 (a diastereoisomer of 2) via a one-step 1,2-difluorination reaction [24]. Py = pyridine; m-CPBA = m-chloroperbenzoic acid, DCM = dichloromethane. The attempted synthesis of 2 via a stepwise fluorination approach (ether series). THF

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• contain an exhaustive list of all enantioselective photocatalytic reactions; however, this review does aim to cover the different strategies that have been developed [5][6][7][8][9][10][11][12][13][14][15][16]. There is a subset of reactions that achieve asymmetry via a stepwise photochemical process

• proceed via a stepwise approach with preformation of the corresponding iminium ion 85. The only catalytic example achieves the same transformation by generating 85 in situ but has reduced yields and enantioselectivities (82:18 er vs 92:8 er for stepwise). Alemán et al. reported that a similar reaction

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• worldwide. To this context, Hirao’s team has reported the synthesis of sumanenemonoone imine compounds 134 and 135 along with the Pd(II) complex 136 formed in a stepwise coordination manner investigated by a titration experiment (Scheme 35) [67]. As can be inspected from Scheme 35, compound 134 was prepared

• by condensing sumanenone 38 with the amino-system 133 in refluxing toluene. The synthesized compound 134 was then treated with Ag2O in THF to afford the corresponding quinonediimine 135 in respectable yield. Furthermore, the stepwise coordination of the imino functionality of compound 135 to the

• palladium(II) was carried out in the presence of PdCl2(MeCN)2 in a stepwise manner, confirmed by UV–vis spectroscopic technique. The cyclopentadienyl (Cp) ligand has its own identity in the field of organometallic chemistry as a plethora of transition metal complexes contain this moiety in their structures

Muyocopronones A and B: azaphilones from the endophytic fungus Muyocopron laterale

• Ken-ichi Nakashima,
• Junko Tomida,
• Tomoe Tsuboi,
• Yoshiaki Kawamura and
• Makoto Inoue

Beilstein J. Org. Chem. 2020, 16, 2100–2107, doi:10.3762/bjoc.16.177

• fraction was then separated by silica gel CC using CHCl3/acetone (stepwise gradient, 1:0, 25:1, 10:1, and 0:1 v/v) as the eluent. The fractions were combined according to TLC analysis to yield five fractions. Fraction 2 was recrystallized in MeOH to yield 3 (96.9 mg), while fraction 3 was subjected to

• silica gel CC with n-hexane/ethyl acetate (stepwise gradient, 3:1, 2:1, and 1:1 v/v) to obtain compound 4 (37.3 mg). Fraction 5 was also subjected to silica gel CC with n-hexane/ethyl acetate (stepwise gradient, 4:1, 3:1, 2:1, and 1:1 v/v) to obtain compounds 2 (263.2 mg) and 1 (241.6 mg) eluted at

Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2H-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction

• Alexander N. Reznikov,
• Dmitry S. Nikerov,
• Anastasiya E. Sibiryakova,
• Victor B. Rybakov,
• Evgeniy V. Golovin and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2020, 16, 2073–2079, doi:10.3762/bjoc.16.174

• to the possibility of creating enantiomerically pure compounds with several stereocenters through the directed regulation of diastereoselectivity in subsequent transformations, which can be realized as stepwise or cascade processes. Due to this reason, the Michael reaction was successfully used over