Syntheses of novel pyridine-based low-molecular-weight luminogens possessing aggregation-induced emission enhancement (AIEE) properties

• Masayori Hagimori,
• Tatsusada Yoshida,
• Yasuhisa Nishimura,
• Yukiko Ogawa and
• Keitaro Tanaka

Beilstein J. Org. Chem. 2022, 18, 580–587, doi:10.3762/bjoc.18.60

• study, we used 1-methyl-4-(methylsulfanyl)-2,5-dioxo-2,5-dihydro-1H-pyrrole-3-carbonitrile (1) with a methylsulfanyl group as a good leaving group. As shown in Scheme 1, the one-pot reaction of 1 with 2-aminopyridine (2a) proceeded by refluxing in ethanol for 2 h to produce the ring-fused pyridine

Chemistry of polyhalogenated nitrobutadienes, 17: Efficient synthesis of persubstituted chloroquinolinyl-1H-pyrazoles and evaluation of their antimalarial, anti-SARS-CoV-2, antibacterial, and cytotoxic activities

• Viktor A. Zapol’skii,
• Isabell Berneburg,
• Ursula Bilitewski,
• Melissa Dillenberger,
• Katja Becker,
• Stefan Jungwirth,
• Aditya Shekhar,
• Bastian Krueger and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2022, 18, 524–532, doi:10.3762/bjoc.18.54

• and a hetarylhydrazine. The oxazolidine 6 was synthetized under mild reaction conditions either from nitrodiene 1 (yield 58%) or from the benzotriazolyl derivative 2c (yield 76%). The increase in yield in case of 2c supports the suggestion that the benzotriazolyl subunit is a better leaving group

• poor leaving group quality of the formal alkoxide. A conceivable mechanistic pathway for the reaction cascade to pyrazole 7 is shown in Scheme 6. Initially, a nucleophilic attack of the NH2 group of 7-chloro-4-hydrazinylquinoline on the C2 position of the oxazolidine ring of 6 leads to the formation of

New efficient synthesis of polysubstituted 3,4-dihydroquinazolines and 4H-3,1-benzothiazines through a Passerini/Staudinger/aza-Wittig/addition/nucleophilic substitution sequence

• Long Zhao,
• Mao-Lin Yang,
• Min Liu and
• Ming-Wu Ding

Beilstein J. Org. Chem. 2022, 18, 286–292, doi:10.3762/bjoc.18.32

• obtained in the presence of K2CO3/CH3CN probably due to the lower reactivity of the -OAc leaving group. In case when R was a 4-NO2C6H4 group, 86% yield of the product 8a was obtained, however, in this case the Passerini product 4a (R = 4-NO2C6H4) was obtained only in 62% yield and the overall yield of

Synthesis of novel [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines and investigation of their fungistatic activity

• Anna V. Korotina,
• Svetlana G. Tolshchina,
• Rashida I. Ishmetova,
• Natalya P. Evstigneeva,
• Natalya A. Gerasimova,
• Natalya V. Zilberberg,
• Nikolay V. Kungurov,
• Gennady L. Rusinov,
• Oleg N. Chupakhin and
• Valery N. Charushin

Beilstein J. Org. Chem. 2022, 18, 243–250, doi:10.3762/bjoc.18.29

• been studied. Similarly to isomeric triazolo[4,3-b][1,2,4,5]tetrazines [36], these derivatives do not form ipso-substitution products with the displacement of a leaving group in the tetrazine ring by the action of CH-acids. Instead, a nucleophile attack on the nitrogen atom of the tetrazine ring does

Mechanistic studies of the solvolysis of alkanesulfonyl and arenesulfonyl halides

• Malcolm J. D’Souza and
• Dennis N. Kevill

Beilstein J. Org. Chem. 2022, 18, 120–132, doi:10.3762/bjoc.18.13

• anhydrides with the chloride leaving group replaced by the appropriate sulfonate leaving group, concerning sulfamoyl chlorides (ZZ'NSO2Cl) with Z and Z' being alkyl or aryl and concerning the solvolysis of chlorosulfate esters (alkoxy- or aryloxysulfonyl chlorides), with the structures ROSO2Cl or ArOSO2Cl

• some other pure or mixed solvent. The sensitivity value m is set at unity for the standard solvolysis and then for some other solvent the solvent ionizing power (Y) will be given by log (k/ko). Subsequently, with the ready availability of cage compounds (1-adamantyl and 2-adamantyl with a leaving group

• assigning the required m value for use in the two-term equation. This problem was minimized by use of the S-methyldibenzothiophenium ion MeDBTh+ (as the trifluoromethanesulfonate) as the standard substrate [39][40] (Scheme 2). This solvolysis has as the leaving group a neutral molecule, dibenzothiophene

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• compared to the more studied late TMs [39][40][41][42][43]. Besides the more recognized concept of TM cross-coupling reactions revolving around an organic electrophile bearing a leaving group and an organometallic nucleophile, there is another large area of cross-coupling reactions that have been under

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• and pinacol/semipinacol rearrangements, the 1,2-shift does not require a leaving group or carbocation intermediate, as the neighboring π system is capable of accepting the migrating group. While the reaction is generally reversible, the product can be favored through four common strategies: (1) the

Allylic alcohols and amines by carbenoid eliminative cross-coupling using epoxides or aziridines

• Matthew J. Fleming and
• David M. Hodgson

Beilstein J. Org. Chem. 2021, 17, 2385–2389, doi:10.3762/bjoc.17.155

• ). Access to allylic alcohol 8 was also achievable (55%, E/Z = 56:44) in a tin-free process using a sulfonyl leaving group, via α-lithiation of sulfone 15 [18] and in the presence of LTMP (Scheme 7). γ-Hydroxysulfone 16 was formed competitively (44%, dr = 50:50), by direct addition of the lithiated sulfone

• hexane (69%, E/Z = 62:38) and the amount of dimer 24 curtailed (8%) by reducing the amount of LTMP from 2 to 1.2 equiv. The viability of a benzyl ether (Scheme 10) in the carbenoid eliminative cross-coupling offered a straightforward way to probe any effect of the size of the leaving group on

• -lithio terminal epoxides or N-Bus-aziridines with α-lithio ethers. Where 1,2-disubstituted alkenes are generated the E/Z stereoselectivity is modest, and preliminary results suggest the size of the leaving group does not play a significant role. However, the geometry of alkene formation might be

Synthesis of phenanthridines via a novel photochemically-mediated cyclization and application to the synthesis of triphaeridine

• Songeziwe Ntsimango,
• Kennedy J. Ngwira,
• Moira L. Bode and
• Charles B. de Koning

Beilstein J. Org. Chem. 2021, 17, 2340–2347, doi:10.3762/bjoc.17.152

• group is a leaving group resulting in the formation of phenanthridines is unprecedented. As is outlined in this paper we set out to investigate the scope and limitations of this reaction resulting in the formation of the phenanthridine skeleton. We also report on the application of this methodology to

• . To be effective, the desired cyclization needs a second methoxy substituent ortho- or para- to the leaving group, which in this case is an aromatic methoxy substituent. Based on these results we suggest two possible mechanisms for these transformations. Both would proceed through an intermediary

• methoxy group as a leaving group have been documented [16]. Our previous research, as shown in Scheme 1, indicated that exposure of the oxime ether 7 to UV radiation resulted in the formation of the phenanthridine 8. Attempts to synthesize the related oxime ethers from biaryl compounds 13a, 13c and 13e

A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids

• Li Liu,
• Yue Li,
• Tiao Huang,
• Dulin Kong and
• Mingshu Wu

Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150

• has a remarkable structural feature: the phosphate moiety is located at the benzylic position as well as at the position α to an amide group, which makes it a good leaving group for the design and development of new reactions. Accordingly, diethyl (2-oxoindolin-3-yl) phosphates 2 have been used

• -3-yl) phosphate 2 is activated by protonation with a haloid acid. Subsequently the phosphate leaving group is eliminated to generate the carbocation intermediate III, which is then followed by rapid combination with a nucleophilic halide ion to form a 3-monohalooxindoles 3 or 4. Conclusion In

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• -atom (80, Scheme 9b) [66]. A similar protocol was adopted by van de Watering in their recent syntheses [67][68]. Sulfides The C2 tethering of indoles with sulfur can be achieved in neutral medium by treatment with various SL2 (L is a leaving group) moieties [69][70]. This is a common method for 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

• polymerization [18], C) chemical synthesis. The use of enzymes has undeniable advantages because it offers the possibility to use unprotected sugars as substrates and guarantees remarkable control of the regio- and stereoselectivity during glycosylation. Mono- or oligosaccharides bearing a reactive leaving group

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• additions [92]. Using MBH acetates 63 as substrates, olefin hydroallylation products 64 were obtained via E1cB elimination of the acetate leaving group driven by the enolate intermediate (Scheme 25B). Six-membered lactones (Scheme 25A, 65a–c) were obtained in a cascade reaction when alkenyl alcohols were

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

• leaving group with isopropylmagnesium chloride gave the desulfinylated product 9e in 79% yield, and the starting sulfoxide 8 was recovered in 10% yield (Table 1, entry 7). Considering the reaction efficiency, accessibility of precursors, and functional group tolerance, the use of isopropylmagnesium

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• ][9][10][11] and other compounds that show different types of biological activities [12][13]. The way to achieve these transformations is by intramolecular cyclizations, involving the free primary amine, and appropriate reactive positions (those positions bearing a leaving group) in the electrophile

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

• ][43][44][45]. Analogous ring-contraction reactions have been described for substrates possessing a good C2 leaving group [42][46][47][48][49][50]. We initially considered converting thioglycosides 14–19 to benzyl glycosides because thioglycosides give glycosyl fluorides on reaction with diethylamino

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

• respect to the apparent versatility of this reagent and more variations could be envisaged. Addition of amines to carbamide derivatives (pathway c) The third main pathway to access biguanides from amines involves the use of carbamide derivatives linked to a leaving group on one carbon atom. These reagents

• can act as a “bisamidine transfer agent” by the addition of an amine, and subsequent elimination of the leaving group. Two types of “biguanide transfer agents” have been developed so far. Depending on the nature of the leaving group they can be separated into either pyrazole or thiomethyl agents

• within 15 minutes in DMF at 110 °C and 62% yield. Addition on S-methylamidinothiourea: Another possibility to create an “amidine transfer reagent” is to install a thiomethyl leaving group on the bisamidine structure. This can be easily achieved using S-methylguanylisothiourea as already described by

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• –base (HSAB) theory the fluoride leaving group is considered to be a hard Lewis base [12][13]. Consequently, a series of fluoride-activating systems containing hard Lewis acidic centers have been published following the first report [7][14][15][16][17]. Among these promoters Sn(II) species (SnCl2–AgX, X

• 1-O-methyl glucoside α-S9 as a glycosyl donor, we have demonstrated that methoxide can act as a mediocre leaving group in liquid SO2 (Scheme S1, Supporting Information File 1). Other limitations for the glycosylation with mannosyl fluoride α-1a include steric hindrance and the presence of a Lewis

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

Synthesis of (Z)-3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones using an Eschenmoser coupling reaction

• Lukáš Marek,
• Lukáš Kolman,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2021, 17, 527–539, doi:10.3762/bjoc.17.47

• ). Alternative electrophilic components for the Eschenmoser coupling reaction The Eschenmoser coupling reaction [36][37] usually starts from α-substituted ketones, esters, malonates, or nitriles. The group in the α-position must be a good leaving group enabling a facile nucleophilic substitution giving the α

• -thioiminium salt and the cleaved leaving group should be a poor nucleophile in order to suppress the reverse reaction. In most cases halogens (mainly Br and I) fulfill these criteria but for highly congested thioamides only triflates gave desirable yields [36]. Moreover, several new alternatives to the

• order to avoid the relatively long synthesis of the precursors we tried to change Br for another leaving group Y (Scheme 4). First, we prepared 3-chlorooxindole (1f) which is available from β-nitrostyrene and acetyl chloride under FeCl3 catalysis [41]. Unfortunately, the Eschenmoser coupling reaction

1,2,3-Triazoles as leaving groups: S_NAr reactions of 2,6-bistriazolylpurines with O- and C-nucleophiles

• Dace Cīrule,
• Irina Novosjolova,
• Ērika Bizdēna and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 410–419, doi:10.3762/bjoc.17.37

• ring at the C6 position of purine to act as leaving group. Keywords: 2,6-bistriazolyl purines; nucleophilic aromatic substitution; purine nucleosides; triazoles; Introduction Modified purine derivatives are an important class of compounds which possess a wide spectrum of biological activities [1][2

• of an SNAr process on partially deactivated purines as the introduced nucleophiles are mostly seen as electron-donating substituents (e.g., R2N-, RS-, RO-). Herein, we report a synthetic extension of this methodology. We have found that the pronounced leaving group character of 1,2,3-triazoles makes

• ). In most cases the full conversion of the starting material was reached in 15–30 min at room temperature, which clearly showed the excellent leaving group ability of the triazolyl ring. These SNAr reactions can also be performed in DMSO or DMF in the presence of K2CO3, but the completion of these

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

• nitrogen with a suitable electrophile, the use of a strong base (e.g., NaH) in combination with the chemical waste being generated (from the leaving group), and potentially unfavorable polar aprotic solvents (DMF, NMP) prompted consideration of a more atom-economical approach. The follow-on work focused on

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

• . These data support the hypothesis that the transient formation of a carbenium ion is the rate-limiting step and the absence of significant solvent participation in the latter. Richard also conducted extensive studies on the impact of the nature of the leaving group (I, Br, OSO2R, etc.) and on the aryl

• , and triflate 45f, which was isolated after basic workup of the reaction (59% yield) [63]. Hence, protonation of 44 led to dialkoxysulfonium triflate 47 along with the release of alcohol 9g. The subsequent formation of the excellent sultine leaving group 46 (assumed to be as good of a leaving group as

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

• stability over a wide pH value range (up to pH 9.0), irrespective of the temperature. This is because in compound 12, the ferulate moiety is not directly linked to the good leaving group 4NTC (pKa = 6.61 [40]). Instead, it is bonded to the linker with a pKa value that can be compared either to that of

• glycerol (pKa = 13.61) or ʟ-arabinose (pKa = 11.31) [41], meaning that it is a poor leaving group. Moreover, our observations regarding the linker stability are consistent with the known stability of the ester linkages under basic conditions. The usefulness of 4NTC–linker–Fe (12) for the characterization