Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• , which have been shown to be particularly sensitive to light [70]. Upon exposure to UV or visible light, thiarubrine A (36) undergoes a desulfurization process to give rise to the corresponding thiophene 37, exhibiting enhanced antibiotic activity (Scheme 10, bottom). This naturally-occurring S-extrusion

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• reported for vinyl sulfides, including dihydrodithiin 13 (Scheme 5a) [36]. In fact, Parham has found that fully unsaturated dithiins can undergo this electrophilic formylation, but at the same time also undergo a ring contraction and an aromatizing desulfurization to yield thiophenes as the main formylated

• products (viz 16, Scheme 5b) [37]. Electrophilic aromatic substitution under less forcing reaction conditions of the same substrate 15, using a room temperature nitration procedure, does yield the expected mononitrated dithiin 17 in good yield, without desulfurization [38]. 1,4-Dithiin-2-carbaldehyde (18

• formation of the cis-vinylcyclopropanes (Scheme 18c and 18d). Desulfurization of the adducts again yields the product of a formal cyclopropanation with a ‘naked’ vinyl carbene species, as demonstrated by the stereoselective synthesis of the protected cis-2-vinylcyclopropan-1-amine 123 (Scheme 18d). 7

One-pot synthesis of 2-arylated and 2-alkylated benzoxazoles and benzimidazoles based on triphenylbismuth dichloride-promoted desulfurization of thioamides

• Arisu Koyanagi,
• Yuki Murata,
• Shiori Hayakawa,
• Mio Matsumura and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 1479–1487, doi:10.3762/bjoc.18.155

• benzimidoyl chloride from thioamides by desulfurization and chlorination, as well as its application to the synthesis of 2-substituted benzazoles. Keywords: benzazole; bismuth; cyclization; desulfurization; thioamide; Introduction In the production of pharmacologically active compounds, 2-substituted

• conventional methods; a notable alternative is the cyclodesulfurization, where intramolecular cyclization is combined with desulfurization from thioamide analogs such as thioureas, thiosemicarbazides, and dithiocarbamate salts under mild reaction conditions [10]. These synthesis methods are effective for

• triphenylbismuth dichloride (Ph3BiCl2) to act efficiently in desulfurization reactions (Scheme 1-I and II). In 2018, we reported the preparation of 2-aminobenzoxazoles by the Ph3BiCl2-mediated cyclodesulfurization of thioureas, which were obtained from 2-aminophenols and isothiocyanates [34]. In 2019, Doris et al

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

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

Phosphodiester models for cleavage of nucleic acids

• Satu Mikkola,
• Tuomas Lönnberg and
• Harri Lönnberg

Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68

• ]. Monoanionic thiophosphorane is sufficiently stable to pseudorotate, but the isomerization is moderately retarded, kO/kS, being 5 and 7 with the RP and SP diasteromers, respectively. The cleavage, in turn, is accelerated: kO/kS(RP) = 0.1 and kO/kS(SP) = 0.3. In addition, desulfurization takes place under these

• ]). Although no desulfurization takes place at high pH, this reaction represents 80% of the disappearance of Up(s)U under neutral conditions. Replacing both of the non-bridging oxygens in a phosphodiester linkage with sulfur does not markedly change the behavior compared to phosphoromonothioates. The thio

Phosphazene-catalyzed desymmetrization of cyclohexadienones by dithiane addition

• Matthew A. Horwitz,
• Elisabetta Massolo and
• Jeffrey S. Johnson

Beilstein J. Org. Chem. 2017, 13, 762–767, doi:10.3762/bjoc.13.75

• of the dithiane moiety via Raney nickel-promoted desulfurization (Scheme 5). To observe any substrate conversion, it was necessary to use a hydrogen atmosphere. Under those conditions, though the dithiane function was removed, degradation occurred. Conclusion In conclusion, we have developed a

• tethered nucleophile. Scope of the transformation. Convex facial additions. Attempted oxidative deacylation. Attempted desulfurization with Raney nickel. Carbonyl deprotection conditions. Supporting Information Supporting Information File 247: Experimental procedures, characterization data and copies of

Diradical reaction mechanisms in [3 + 2]-cycloadditions of hetaryl thioketones with alkyl- or trimethylsilyl-substituted diazomethanes

• Grzegorz Mlostoń,
• Paulina Pipiak and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2016, 12, 716–724, doi:10.3762/bjoc.12.71

• spontaneous desulfurization, are the main products. In contrast, reactions with diazoethane occurred predominantly via initially formed diradicals, which in cascade processes gave sterically crowded 4,4,5,5-tetrahetaryl-1,3-dithiolanes as major products. Finally, the reaction of dihetaryl thioketones with

• , formed via spontaneous desulfurization of 8b, were obtained as the sole products, in the experiment carried out at –15 ºC, the sterically crowded 1,3-dithiolane 10b was also detected as a minor product (14% yield, Table 1). In the latter case, thiirane 8b and ethene 9b were found in 24 and 37% yield

• -diphenyl-3-methylthiirane (8i) and 1,1-diphenylpropene (9i) as the product of its desulfurization. On the other hand, the experiment with 1a and 7b performed at room temperature led to the 1,3-dithiolane 10i as the major product (87%) accompanied by small amounts of thiirane 8i and ethene 9i [23]. A

From steroids to aqueous supramolecular chemistry: an autobiographical career review

• Bruce C. Gibb

Beilstein J. Org. Chem. 2016, 12, 684–701, doi:10.3762/bjoc.12.69

• first step, the unoptimized desulfurization of 2-thio-6-methyluracil using Raney-Nickel to form 6-methyl-4-hydroxypyrimidine (Scheme 2). It turned out I was a wiz at this organic synthesis lark (as Derek liked to say). I took the yield from 73% to quantitative by doing what organic chemists do, changing

Nucleic acids through condensation of nucleosides and phosphorous acid in the presence of sulfur

• Tuomas Lönnberg

Beilstein J. Org. Chem. 2016, 12, 670–673, doi:10.3762/bjoc.12.67

• elemental sulfur. Desulfurization and subsequent digestion of the products by P1 nuclease revealed that nearly 80% of the internucleosidic linkages thus formed were of the canonical 3´,5´-type. Keywords: H-phosphonate; nucleic acid; polymerization; phosphite; sulfurization; Introduction Arguably the most

• tetrameric products, (B) the product mixture after desulfurization by iodine and (C) the product mixture after P1 nuclease digestion of the desulfurized material; Dionex DNASwiftTM column (150 × 5 mm, monolithic); flow rate = 1.5 mL min−1; linear gradient (2 to 35% over 20 min) of 330 mM NaClO4 in 20 mM TRIS

Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid

• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Anna Gajda,
• Tadeusz Gajda,
• Anna Makal,
• Arnaud Brosseau and
• Rémi Métivier

Beilstein J. Org. Chem. 2015, 11, 2451–2458, doi:10.3762/bjoc.11.266

• desulfurization of thioamides to amides via reaction with Oxone®. Now we want to apply this approach to the synthesis of N-thioacyl- and acyl derivatives of 1-aminoalkylphosphonates from arenes and 1-(isothiocyanato)alkylphosphonates. 1-Aminoalkylphosphonates and their derivatives are compounds of biological

Synthesis of 1,2-cis-2-C-branched aryl-C-glucosides via desulfurization of carbohydrate based hemithioacetals

• Henok H. Kinfe,
• Fanuel M. Mebrahtu,
• Mandlenkosi M. Manana,
• Kagiso Madumo and
• Mokela S. Sokamisa

Beilstein J. Org. Chem. 2015, 11, 583–588, doi:10.3762/bjoc.11.64

• hydrogenolytic desulfurization of suitably orientated carbohydrate based hemithioacetals. 1,2-cis-2-Hydroxymethyl and 2-carbaldehyde of aryl-C-glucosides have been synthesized using the current strategy in very good yields. The 2-carbaldehyde-aryl-C-glucosides have been identified as suitable substrates for the

• stereospecific preparation of 2,3-unsaturated-aryl-C-glycosides (Ferrier products). Keywords: aryl-C-glucoside; desulfurization; Ferrier product; hemithioacetal; Introduction 1-C (C-glycosides) and 2-C-branched carbohydrates are important carbohydrate analogues which have found wide application in

• prepared from thiochroman 1 and we envisioned that a careful desulfurization could provide aryl-C-glucoside 4 with inherent 1,2-cis relationship between the easily transformable 2-C-branch and the aryl group at the C-2 and C-1 positions, respectively. Although detailed studies on the desulfurization of

On the strong difference in reactivity of acyclic and cyclic diazodiketones with thioketones: experimental results and quantum-chemical interpretation

• Andrey S. Mereshchenko,
• Alexey V. Ivanov,
• Viktor I. Baranovskii,
• Grzegorz Mloston,
• Ludmila L. Rodina and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2015, 11, 504–513, doi:10.3762/bjoc.11.57

• =S ylides bearing at least one acyl group is identified as the 1,5-electrocyclization into 1,3-oxathioles. However, in the case of diazomalonates, the dominating process is 1,3-cyclization into thiiranes followed by their spontaneous desulfurization yielding the corresponding alkenes. Finally

• diazo compounds 1a–c with thioketones 2a and 2b results in the formation of oxathioles 3a–c and 3’a–c, while with diazomalonate 1d the thiiranes 4d, 4’d and alkenes 5d, 5’d, the desulfurization products of thiiranes are the principal reaction products [20]. To understand the mechanism of alkene 5’d

• ’d and the corresponding alkene 5’d resulting from desulfurization are the main products formed at elevated temperatures when the reaction is thermodynamically controlled. At the same time, the lower activation barrier of 1,5-electrocyclization (ΔGa# = 8.7 kcal·mol−1) as compared to 1,3

Highly selective electrochemical fluorination of dithioacetal derivatives bearing electron-withdrawing substituents at the position α to the sulfur atom using poly(HF) salts

• Bin Yin,
• Shinsuke Inagi and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2015, 11, 85–91, doi:10.3762/bjoc.11.12

• . Further anodic fluorodesulfurization occurs to provide the corresponding difluorinated products 4b and 4d, respectively. On the other hand, the desulfurization of intermediate D followed by reaction with fluoride provides the corresponding fluorodesulfurization products 3b, 3d, and 3f. When high HF

• free base, Et3N was used. As mentioned, the yield of monofluorodesulfurization product 3f increased markedly by using high HF content salt, Et3N·5HF. In sharp contrast, in the case of substrate 1h having a cyano group, α-fluorination without desulfurization always took place even when Et3N·5HF and

• sulfides having an electron-withdrawing group. Anodic fluorination of dithioacetals. Plausible reaction mechanism for anodic fluorination of 1b, 1d, and 1f. Mechanism for suppression of the elimination of HF (deprotonation) and preferable desulfurization of D at high concentrations of HF in an electrolytic

Olefin cross metathesis based de novo synthesis of a partially protected L-amicetose and a fully protected L-cinerulose derivative

• Bernd Schmidt and
• Sylvia Hauke

Beilstein J. Org. Chem. 2014, 10, 1023–1031, doi:10.3762/bjoc.10.102

• for many years. For example, D-amicetose has been obtained from other carbohydrates through ethanethiolysis and subsequent Ni-catalyzed desulfurization [18][19], by reduction of the corresponding aldonolactone [20], or by conversion of a protected mannopyranoside into the 2,3-unsaturated enopyranoside

Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones – First evidence for the 1,3-oxathiole–thiocarbonyl ylide interconversion

• Valerij A. Nikolaev,
• Alexey V. Ivanov,
• Ludmila L. Rodina and
• Grzegorz Mlostoń

Beilstein J. Org. Chem. 2013, 9, 2751–2761, doi:10.3762/bjoc.9.309

• most reactive diazodicarbonyl compound was diazoacetylacetone. In the case of dimethyl diazomalonate competitive 1,3-electrocyclization yielded the corresponding thiirane at elevated temperature, which after spontaneous desulfurization produced a tetrasubstituted alkene. To explain the observed

• spontaneous desulfurization and convert into tetrasubstituted alkenes [20]. 2) Pathway B assumes a stepwise cycloaddition of the diazo-1,3-dipole with the C=S bond leading to the initial formation of the diazonium zwitterion 11. This step is followed either by the ring closure to give thiadiazoline 10 or by

• . Thus, the observed process is the first example of a reversible interconversion of a 1,3-oxathiole into the corresponding thiirane via the corresponding thiocarbonyl ylide. Subsequently formed thiirane easily undergoes desulfurization, and finally the respective alkene is formed as an isolable compound

Alternaric acid: formal synthesis and related studies

• Michael C. Slade and
• Jeffrey S. Johnson

Beilstein J. Org. Chem. 2013, 9, 166–172, doi:10.3762/bjoc.9.19

• and the wealth of precedents for single-step desulfurization to alkanes [36][37][38][39][40]. The racemic synthesis of the requisite aldehyde proved straightforward (see Supporting Information File 1). Most importantly, in initial three-component coupling reactions with vinyl nucleophile 4 and silyl

• was enabled. Most importantly, this provides the first example of such a highly functionalized nucleophile being used in a silyl glyoxylate based three-component coupling reaction. Remaining tasks for the complete formation of the natural product include desulfurization [49], deprotection [50], and

Imidazolinium and amidinium salts as Lewis acid organocatalysts

• Oksana Sereda,
• Nicole Clemens,
• Tatjana Heckel and
• René Wilhelm

Beilstein J. Org. Chem. 2012, 8, 1798–1803, doi:10.3762/bjoc.8.205

• desulfurization of the products containing a thiol or thiocarbonyl group. Keywords: Diels–Alder; ionic liquids; organocatalysis; soft Lewis acids; thiiranes; thioesters; Introduction Salts with melting points below 100 °C are known as ionic liquids and are often used as novel solvents for reactions and

• hydrogen-bond activation catalysts [18]. The utilization of the soft Lewis basic sulfur groups in this reaction is rare. Often mercury Lewis acids are applied [19][20][21][22] to activate the sulfur group and there is also the risk of desulfurization [23]. The only known asymmetric Diels–Alder reaction

A simple and efficient dual optical signaling chemodosimeter for toxic Hg(II)

• Sabir H. Mashraqui,
• Sapna A. Tripathi,
• Sushil S. Ghorpade and
• Smita R. Britto

Beilstein J. Org. Chem. 2012, 8, 1352–1357, doi:10.3762/bjoc.8.155

• optical targeting of toxic Hg2+ in buffered aqueous DMSO. The Hg2+-mediated desulfurization of the probe is translated into selective dual signaling of Hg2+ by means of color bleaching and fluorescence amplification while several other metal ions, including potentially competing Ag+, Cu2+ and Pb2+, afford

• ratiometric or switch-on responses even for the paramagnetic metal ions [17][18][19]. The first luminescence chemodosimeter for Hg2+ was developed by Czarnik et al. and was based on the Hg2+-mediated desulfurization of anthracene-thioamide chromophore [20][21]. Following this pioneering report, several other

• Hg2+ with the thione group of acrithion 2, forming an intermediate thioacridinium–Hg+ complex. This phenomena would polarize the C=S bond and therefore facilitate nucleophilic attack by water at the electrophilic C9 position. Subsequently, the hydrolytic desulfurization is expected to form compound 1

Synthetic glycopeptides and glycoproteins with applications in biological research

• Ulrika Westerlind

Beilstein J. Org. Chem. 2012, 8, 804–818, doi:10.3762/bjoc.8.90

• ., auxiliary based protocols, desulfurization methods or sugar-assisted chemical ligation (SAL) are all examples of expanded NCL techniques [70][71][72][73][74][75][76][77]. According to the auxiliary-based ligation strategy, a thiol-containing mimic replaces the N-terminal cysteine; the mimic group is then

• functional groups. After ligation the side-chain thiol could be removed by Raney nickel treatment. Employing the desulfurization methodology, thiol amino acids could be converted to alanine, valine, phenylalanine and threonine residues [71][72][73][74][75][76]. As an alternative to Raney nickel reduction, a

• radical-induced desulfurization method was recently reported [76]. An example of the desulfurization method is illustrated in Scheme 6. After the NCL-reaction, the γ-thiol valine at the ligation site could be converted to a valine by treatment with tris(2-carboxyethyl)phosphine (TCEP), t-BuSH, and the

Convergent syntheses of Le^X analogues

• An Wang,
• Jenifer Hendel and
• France-Isabelle Auzanneau

Beilstein J. Org. Chem. 2010, 6, No. 17, doi:10.3762/bjoc.6.17

• respectively to the n-hexyl and 6-aminohexyl trisaccharide targets. Unexpectedly, the 6-acetylthiohexyl analogue underwent desulfurization and gave the n-hexyl glycoside product, whereas the 6-benzylthiohexyl analogue gave the desired disulfide trisaccharide dimer. This study constitutes a particularly

• efficient and convergent preparation of these three Lex analogues. Keywords: Birch reduction; convergent synthesis; desulfurization; Lewis X; Introduction Our group is involved in the design of new anti-cancer vaccines based on the Tumor Associated Carbohydrate Antigen (TACA) dimeric Lex (dimLex) [1][2][3

• conditions did not lead to the desired corresponding thiol or disulfide product but produced the hexyl glycoside 1. The mechanism proposed to explain this reductive desulfurization is shown in Scheme 4. It involves first a single electron transfer to the thioacetyl group that is followed by the cleavage of

Trifluoromethyl ethers – synthesis and properties of an unusual substituent

• Frédéric R. Leroux,
• Baptiste Manteau,
• Jean-Pierre Vors and
• Sergiy Pazenok

Beilstein J. Org. Chem. 2008, 4, No. 13, doi:10.3762/bjoc.4.13

• desulfurization-fluorination has been disclosed by Hiyama [24][25][26][27]. When dithiocarbonates (2, xanthogenates) are exposed to a huge excess of hydrogen fluoride-pyridine and 1,3-dibromo-5,5-dimethylhydantoin, trifluoromethyl ethers form in moderate to excellent yields (Scheme 5 and Table 5). What makes this

• a chlorination/fluorination sequence. Preparation of trifluoromethyl ethers via an in situ chlorination/fluorination sequence. Preparation of trifluoromethyl ethers via chlorothionoformates. Preparation of trifluoromethyl ethers via fluoroformates. Oxidative desulfurization-fluorination toward

• trifluoromethyl ethers. Mechanism of the oxidative desulfurization-fluorination. Umemoto's O-(trifluoromethyl)dibenzofuranium salts 4 as CF3-transfer agents. Togni's approach using hypervalent iodine compounds as CF3-transfer agents. TAS OCF3 as a nucleophilic OCF3-transfer agent. Nitration of trifluoromethoxy