Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• corresponding thiones. The yield of reaction products ranges from 42 to 80%. The crystal structures of catechols with 3-nitropyridine or 1,3,4-oxadiazole-2(3H)-thione moieties were established by single-crystal X-ray analysis. The possibility of forming intra- and intermolecular hydrogen bonds has been

• : antioxidant activity; catechol thioethers; heterocycles; redox-transformations; thiones; Introduction Synthetic derivatives of polyphenols, in particular catechol (hydroquinone), represent a promising group of pharmacologically active substances [1][2]. Catechol-containing compounds demonstrate

• , compounds 6–9 are products of alkylation of the nitrogen atom of the heterocycle. Thiones 6–9 were obtained in 40–79% yield (Scheme 1,b). The structures of synthesized compounds were confirmed by the spectral methods IR-, 1H NMR, 13C{1H} NMR spectroscopy (Figures S1–S18 in Supporting Information File 1

O,S,Se-containing Biginelli products based on cyclic β-ketosulfone and their postfunctionalization

• Kateryna V. Dil and
• Vitalii A. Palchykov

Beilstein J. Org. Chem. 2024, 20, 2143–2151, doi:10.3762/bjoc.20.184

• Biginelli synthesis of dihydropyrimidinones/thiones/selenones via acetic acid or solvent-free Yb(OTf)3-catalyzed tandem reaction of β-ketosulfone (dihydro-2H-thiopyran-3(4H)-one-1,1-dioxide), an appropriate urea, and arylaldehyde has been developed. The reaction proceeds with high chemo- and

Domino reactions of chromones with activated carbonyl compounds

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1256–1269, doi:10.3762/bjoc.20.108

• alcohol and oxidation of the latter resulted in formation of the final product. The reason for the change of the regioselectivity of cyclization, as compared to the formation of products 36, remains unclear at present. The reaction of 3-halochromones with 3H-indole-2-thiones (thiooxindoles) 38a–c afforded

• attack of the sulfur to the bromide (intermediate AC) and subsequent ring-cleavage. In most reactions, DBU was employed as the base. In case of products derived from N-unsubstititued 3H-indole-2-thiones (R3 = H), employment of potassium carbonate proved to be advantageous. Similarly to the formation of

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• to literature procedures [14][19][20], as were the 1,3-dithiole-2-thiones 2 and 3 [21]. Fluorenone 5 is commercially available. The new building blocks 7 and 8 were prepared according to related literature procedures [21], as described in Supporting Information File 1. Our first objective was to

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

• reactions with elemental sulfur [23][24][25], resulting in the generation of non-enolizable imidazole-2-thiones. At first, the alkylation of 2-unsubstituted imidazole N-oxides 40 took place in the presence of an equimolar quantity of benzyl bromide in CH2Cl2 at rt providing the (N-benzyloxy)imidazolium

• salts 41. The latter underwent deprotonation in the presence of triethylamine in pyridine to generate the carbene intermediates 42 (Scheme 9). After that, the optically active imidazole-2-thiones 43 were obtained through the reaction with elemental sulfur. In CHCl3 solutions, the study of the optical

• rotation of the isolated products 43a–h did not show any racemization under the standard reaction conditions. Thereafter, imidazolium salts 45a–d, obtained from imidazole N-oxides 44a–d, provided the desired optically active 3-butoxyimidazole-2-thiones 47a–d in 66–83% yield using triethylamine in pyridine

Synthesis of sulfur karrikin bioisosteres as potential neuroprotectives

• Martin Pošta,
• Václav Zima,
• Lenka Poštová Slavětínská,
• Marika Matoušová and
• Petr Beier

Beilstein J. Org. Chem. 2022, 18, 549–554, doi:10.3762/bjoc.18.57

• effect of bioisosteric exchange together with the effect of substitution along the karrikin backbone on the inhibitory activity against AChE. The target sulfur analogues of karrikins are shown on Figure 2. Results and Discussion Synthesis of KAR analogues with sulfur in position C2 A series of thiones

• (14), respectively, following a published procedure [21][23], while karrikin KAR2 (2) was synthesized from ᴅ-xylose [24]. The conversion of karrikins 1–4 to the corresponding C2 thiones 9–12 was accomplished using microwave-assisted heating with Lawesson’s reagent and hexamethyldisiloxane (HMDO

Synthesis of functionalized imidazo[4,5-e]thiazolo[3,2-b]triazines by condensation of imidazo[4,5-e]triazinethiones with DMAD or DEAD and rearrangement to imidazo[4,5-e]thiazolo[2,3-c]triazines

• Alexei N. Izmest’ev,
• Dmitry B. Vinogradov,
• Natalya G. Kolotyrkina,
• Angelina N. Kravchenko and
• Galina A. Gazieva

Beilstein J. Org. Chem. 2021, 17, 1141–1148, doi:10.3762/bjoc.17.87

• -triazine-3-thiones with acetylenedicarboxylic acid dimethyl and diethyl esters (DMAD and DEAD) and subsequent base-catalyzed rearrangement of the obtained imidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazines into regioisomeric imidazo[4,5-e]thiazolo[2,3-c]-1,2,4-triazine derivatives. Keywords: amidine

• based on the sequential condensation of imidazo[4,5-e]-1,2,4-triazine-3-thiones 3 with DMAD or DEAD and skeletal rearrangement of linear imidazo[4,5-e]thiazolo[3,2-b]-1,2,4-triazines 4 into isomeric imidazo[4,5-e]thiazolo[2,3-с]-1,2,4-triazines 5 having an angular structure. Results and Discussion We

• started by examining the regioselectivity of the condensation of imidazo[4,5-e]triazine-3-thiones 3 with DEAD. The effects of temperature, the nature of the solvent, and the structure of the starting substrates on the total yields and ratios of isomeric products 4 and 5 were investigated (Table 1, see

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

• reported methods are efficient to provide the desired 1,2-disubstituted benzimidazoles, dihydropyrimidinones/-thiones and 2-amino-4-aryl-3,5-dicarbonitrile-6-sulfanylpyridines, there are still some drawbacks, which include the use of expensive catalysts, the preparation of the catalyst, long reaction times

• irradiation (USI). In this paper, we wish to report the use of NDL as a heterogeneous green catalyst for the synthesis of the 1,2-disubstituted benzimidazoles 3, the dihydropyrimidinones/-thiones 7, and the 2-amino-4-(hetero)aryl-3,5-dicarbonitrile-6-sulfanylpyridines 11 via C–N, C–C, and C–S bond-forming

• , the elemental composition of the NDL catalyst was determined by EDAX analysis (Figure 6). The catalytic activity of the NDL for the synthesis of the 1,2-disubstituted benzimidazoles 3, the dihydropyrimidinones/-thiones 7, and the 2-amino-4-(hetero)aryl-3,5-dicarbonitrile-6-sulfanylpyridines 11 was

One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

• Gui-Feng Kang and
• Gang Zhang

Beilstein J. Org. Chem. 2020, 16, 1447–1455, doi:10.3762/bjoc.16.120

• and orthoformates and provided a rapid entry to a variety of 4-aryl-6-(alkylthio)-3,4-dihydro-1,3,5-triazine-2(1H)-thiones (29 examples). The synthetic strategy relies on the dual role of thiourea in the cyclization with the aldehydes and the alkylation via an intermediate imidate formation. The

• novel multicomponent reactions to access diverse triazinethione derivatives, we recently synthesized a series of 4-aryl-6-(alkylthio)-3,4-dihydro-1,3,5-triazine-2(1H)-thiones from aldehydes, thiourea and suitable orthoformates. This strategy was straightforward and the reaction conditions were mild

• alkylation process [39]. Finally, proton transfer processes afford the desired product 6 and byproduct 5. Conclusion In summary, we have developed a simple and efficient method for the synthesis of 4-aryl-6-(alkylthio)-3,4-dihydro-1,3,5-triazine-2(1H)-thiones through a catalyst-free multicomponent reaction

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• accompanied by elimination reactions. 3. Synthesis via cycloadditions Cycloadditions, especially the photochemical [2 + 2] cycloaddition (thia-Paternò–Büchi reaction) of thiones and thioamides with olefins [15][16][17][18], and formal cycloadditions are alternative routes for the construction of thietane

• nm UV light [63]. In 1978, Gotthardt and Nieberl investigated the UV light-induced [2 + 2] cycloaddition reaction of thiones with cyclic alkenes and realized the synthesis of spirothietane derivatives. Under n → π* excitation using Na light, xanthione (196) reacted with acenaphthylene (197), indene

• mechanistic studies. The reactivity of the substituted allenes towards triplet aromatic thiones was investigated. The product analysis revealed the formation of thietanes and occasionally of [4 + 2] cycloadducts (thiopyrans) generally in high overall yields. Steady-state measurements showed that electron

KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

• Qiao Lin,
• Shiling Zhang and
• Bin Li

Beilstein J. Org. Chem. 2020, 16, 492–501, doi:10.3762/bjoc.16.44

• synthetic chemists. However, only a few examples are reported for the synthesis of N-substituted thiazolidinones although the synthetic method of thiazolidinone was described in 1993 [16]. Frost and co-workers explored an efficient ruthenium-catalyzed O-to-S-alkyl migration of N-alkyloxazolidine-2-thiones

Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Katarzyna Urbaniak,
• Marcin Jasiński,
• Vladyslav Bakhonsky,
• Peter R. Schreiner and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2019, 15, 497–505, doi:10.3762/bjoc.15.43

• analogously to those of 1-alkylimidazole 3-oxides to give imidazol-2-thiones and imidazol-2-ones, respectively. Treatment of 1-(adamantyloxy)imidazole 3-oxides with Raney-Ni afforded the corresponding imidazole derivatives without cleavage of the N(1)–O bond. Finally, the O-alkylation reactions of the new

• -aromatization of the imidazole ring. The same mechanism governs sulfur-transfer reactions with cycloaliphatic thioketones yielding the corresponding imidazole-2-thiones [13]. The isomerization of N-oxides 1 into the corresponding imidazol-2-ones can be easily performed by treatment with acetic anhydride at room

• min resulted in decomposition of the starting material, and in this case, the expected imidazole-2-one 9 could not be detected in the crude reaction mixture. Sulfur-transfer reactions offer an attractive approach to imidazole-2-thiones starting with 2-unsubstituted imidazole N-oxides [13]. The

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• alkylation of 1,3-dithiole-2-thiones C and E and the corresponding TTF molecules derived from them often in very good yields. An additional strategy to obtain non-symmetrically substituted TTF derivatives is the stepwise reaction of TTF tetrathiolate with different electrophiles [48]. Another important

• synthetic advance is the phosphite-mediated heterocoupling of 1,3-dithiol-2-thiones F and 1,3-dithiol-2-ones G which provides efficient access to TTFs with two differently substituted 1,3-dithiol rings in an efficient way [49]. Simple heating of both monomers (ketone and thioketone) in P(OMe)3 or P(OEt)3

• yields the desired hetero dimers H often in good yields. In combination with transchalcogenation reactions [50], which allow the transformation of 1,3-dithiol-2-thiones into the corresponding ketones in excellent yields, various types of non-symmetrically substituted TTF moieties can be implemented into

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• . Carbon disulfide Formation of 1,3-oxathiolane-2-thiones In 2016, Yadav and co-workers reported a photoredox-catalyzed C–S bond formation with carbon disulfide (CS2) as starting material (Scheme 30) [65]. The reaction of CS2 with styrenes under visible-light irradiation and Eosin Y as organic

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

Beilstein J. Org. Chem. 2017, 13, 1828–1849, doi:10.3762/bjoc.13.178

• and 1,2-phenylenediamine, benzimidazolidine-2-thiones 14a–c were isolated in 100% yields via cyclization of an unstable intermediate 13 (Scheme 3b,c). Compared to the solvent-free synthesis, the corresponding solution reactions resulted in lower yields (81–95%). Li and co-workers conducted a mortar

• bis-thiourea derivative by milling 1,2-diisothiocyanate with two equivalents of an amine failed and resulted in the formation of benzimidazolidine-2-thiones 14a–c by cyclization of the mono-thiourea intermediate 13 (Scheme 3), our reaction design was based on the click-coupling of o-pda with either

N-Propargylamines: versatile building blocks in the construction of thiazole cores

• S. Arshadi,
• E. Vessally,
• L. Edjlali,
• R. Hosseinzadeh-Khanmiri and
• E. Ghorbani-Kalhor

Beilstein J. Org. Chem. 2017, 13, 625–638, doi:10.3762/bjoc.13.61

• -propargylamines and carbon disulfide The first example of a cyclization of N-propargylamines 1 with carbon disulfide to lead to 5-methylenethiazolidine-2-thiones 2 was reported in 1949 by Batty and Weedon. The reaction took place in refluxing ethanol and generally afforded the corresponding products in good

• thiazole-2-thiones 3 in high yields (Scheme 1) [75]. Thirty-six years later, Hanefeld and Bercin synthesized a series of 2-(alkylthio)thiazoles by employing the aforementioned method as the key step [76]. In 2001, Shi and Shen found that using a Pd(PPh3)4/toluene system clearly accelerated this

• thiazole-2-thiones 3 through the thermal cyclocondensation of N-propargylamines 1 with carbon disulfide as developed by Batty and Weedon [75]. (a) One-pot synthesis of 2-benzylthiazolo[3,2-a]benzimidazoles 6 through a base-catalyzed cascade reaction of internal N-propargylamines 4 and CS2. (b) Synthesis of

A novel method for heterocyclic amide–thioamide transformations

• Walid Fathalla,
• Ibrahim A. I. Ali and
• Pavel Pazdera

Beilstein J. Org. Chem. 2017, 13, 174–181, doi:10.3762/bjoc.13.20

• phthalizin-1-thiones C7 and C8a. Synthesis of quinolin-2-thiones C9 and quinoxalin-2-thiones C10–C13a. Supporting Information Supporting Information File 60: Additional experimental and analytical data. Acknowledgements We would like to thank the Department of Organic Chemistry, Faculty of Science, Masaryk

Chemical probes for competitive profiling of the quorum sensing signal synthase PqsD of Pseudomonas aeruginosa

• Michaela Prothiwa,
• Dávid Szamosvári,
• Sandra Glasmacher and
• Thomas Böttcher

Beilstein J. Org. Chem. 2016, 12, 2784–2792, doi:10.3762/bjoc.12.277

• microwave assistance (Scheme 1). Thionation of the 4-position of 1, 4, 6, 10, 13 and 15 using P4S10 in pyridine under reflux conditions gave the 4-thiones 2, 5, 7, 11, 14 and 16 in yields between 60–80%, respectively (Scheme 1). The HHQ-oxime (3) was synthesized from HHQ (1) by conversion in the benzyl

Interactions between 4-thiothymidine and water-soluble cyclodextrins: Evidence for supramolecular structures in aqueous solutions

• Vito Rizzi,
• Sergio Matera,
• Paola Semeraro,
• Paola Fini and
• Pinalysa Cosma

Beilstein J. Org. Chem. 2016, 12, 549–563, doi:10.3762/bjoc.12.54

• attributed to the reduction of the thiocarbonyl group, (C4=S) (Figure 3, solid black line). In particular, as reported in [37] about the electrochemical properties of some thiones, the redox process involving the thionucleoside could be attributable to an electron transfer process centered on the C=S moiety

Spiro-fused carbohydrate oxazoline ligands: Synthesis and application as enantio-discrimination agents in asymmetric allylic alkylation

• Jochen Kraft,
• Martin Golkowski and
• Thomas Ziegler

Beilstein J. Org. Chem. 2016, 12, 166–171, doi:10.3762/bjoc.12.18

• -isopropylidene-β-D-psicopyranose, respectively. The latter compounds were partially deprotected under acidic conditions followed by condensation with thiocyanic acid to give an anomeric mixture of the corresponding 1,3-oxazolidine-2-thiones. The anomeric 1,3-oxazolidine-2-thiones were separated after successive

• acidic conditions gave the corresponding diols 3 [20] and 4 as anomeric mixtures. Condensation of the latter with thiocyanic acid in a Ritter-type reaction according to a slightly modified procedure described by Tatibouët et al. [21] gave an anomeric mixture of 1,3-oxazolidin-2-thiones 5 and 6

• , respectively. The anomers of 5 and 6 could not be separated by standard column chromatography though. Thiocarbamate 5 was previously mentioned in the literature [21], but due to the fast anomerisation and the relative instability of 1,3-oxazolidin-2-thiones it was never characterized. However, in our hands

[2.2]Paracyclophane derivatives containing tetrathiafulvalene moieties

• Laura G. Sarbu,
• Lucian G. Bahrin,
• Peter G. Jones,
• Lucian M. Birsa and
• Henning Hopf

Beilstein J. Org. Chem. 2015, 11, 1917–1921, doi:10.3762/bjoc.11.207

• 1,3-dithiolium perchlorates 5a–c in the presence of tetrafluoroboric acid led to the degradation of the substrate. The second approach for the synthesis of tetrathiafulvalenes involves the desulfurative coupling of 1,3-dithiol-2-thiones in the presence of alkyl phosphites. 1,3-Dithiol-2-thiones are

Advances in the synthesis of functionalised pyrrolotetrathiafulvalenes

• Luke J. O’Driscoll,
• Sissel S. Andersen,
• Marta V. Solano,
• Dan Bendixen,
• Morten Jensen,
• Troels Duedal,
• Jess Lycoops,
• Cornelia van der Pol,
• Rebecca E. Sørensen,
• Karina R. Larsen,
• Kenneth Myntman,
• Christian Henriksen,
• Stinne W. Hansen and
• Jan O. Jeppesen

Beilstein J. Org. Chem. 2015, 11, 1112–1122, doi:10.3762/bjoc.11.125

• prepare BPTTFs using homocoupling reactions and functionalised MPTTFs using cross-coupling reactions with a variety of 1,3-dithiole-2-thiones (19). Subsequently, the incorporation of more complex functionality is discussed. We show how the 2-cyanoethyl protecting group can be used to afford MPTTFs

• -thiones 19 [38]. These reactions (Scheme 3 and Table 1) use an excess of 19 to minimise the formation of 5a as a byproduct, making it possible to isolate tosylated MPTTFs (such as 4a–f) in high yields. This is believed to be due to the higher reactivity of sulfur ylide intermediates (formed from 1,3

• -dithiole-2-thiones) with 1,3-dithiole-2-ones than with excess 1,3-dithiole-2-thiones [39]. Table 1 lists a selection of N-tosylated MPTTFs 4a–f prepared from 6 and 19a–f, respectively, with yields ranging from 70–87% despite the concomitant formation of homocoupled byproducts. Compound 7 (and related

Regioselective synthesis of chiral dimethyl-bis(ethylenedithio)tetrathiafulvalene sulfones

• Flavia Pop and
• Narcis Avarvari

Beilstein J. Org. Chem. 2015, 11, 1105–1111, doi:10.3762/bjoc.11.124

• -BEDT-TTF precursor. Compounds (S,S)-1 and (R,R)-1 were synthesized in two steps from the corresponding enantiopure dithiole-thiones (S,S)-5 and (R,R)-5 and the dithiolone-dithiopropionitrile 4 (Scheme 2). In the first step the phosphite-mediated heterocoupling between the two units provides the

A new and convenient synthetic way to 2-substituted thieno[2,3-b]indoles

• Roman A. Irgashev,
• Arseny A. Karmatsky,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2015, 11, 1000–1007, doi:10.3762/bjoc.11.112

• , including oxidative cyclization of indolin-2-thiones 1 [20], radical or palladium catalyzed cyclization of 3-(2-bromoindol-3-yl)acrylonitriles 2 [21][22], intramolecular CH/NH-coupling in benzo[b]thiophenes 3 [23], AlCl3 catalyzed recyclization of 2-(2-isothiocyanatophenyl)furanes 4 [24], reductive

Derivatives of the triaminoguanidinium ion, 3. Multiple N-functionalization of the triaminoguanidinium ion with isocyanates and isothiocyanates

• Jan Szabo,
• Kerstin Karger,
• Nicolas Bucher and
• Gerhard Maas

Beilstein J. Org. Chem. 2014, 10, 2255–2262, doi:10.3762/bjoc.10.234

• tris(thiourea) derivative, could result. With phenyl isothiocyanate and its 4-nitro derivative, however, 3-hydrazinyl-1H-1,2,4-triazole-5(4H)-thiones 10a,b were obtained as major products in 57 and 68% yield, respectively (Scheme 5). In the case of (4-nitrophenyl) isothiocyanate, the bis(arylthiourea

• , which are reduced to form 1,2,3-tris(alkylamino)guanidinium salts, and finally N-carbamoylation with arylisocyanates. With (p-toluenesulfonyl) isocyanate only a N-mono-sulfonylcarbamoylation could be achieved. In contrast, 3-hydrazinyl-1H-1,2,4-triazole-5(4H)-thiones were obtained from 1,2,3-tris