Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• homolytic cleavage of the C–S bond, providing the sulfonyl radical 186. The sulfonyl radical 186 can then approach anti to the oxazolidinone moiety in 180, generating a β-sulfonyl radical 187, which, once trapped by another sulfonyl cyanide molecule 181, affords the desired product 182, and the sulfonyl

[1,3]/[1,4]-Sulfur atom migration in β-hydroxyalkylphosphine sulfides

• Katarzyna Włodarczyk,
• Piotr Borowski and
• Marek Stankevič

Beilstein J. Org. Chem. 2020, 16, 88–105, doi:10.3762/bjoc.16.11

• activation energy (31.0 kcal/mol), which was followed by slight stabilization of the formed γ-carbanion (−6.1 kcal/mol). The latter should then undergo intramolecular C–S bond formation, followed by hydrolysis, finally leading to the rearranged product. It was then decided to investigate the

Synthesis of novel sulfide-based cyclic peptidomimetic analogues to solonamides

• José Brango-Vanegas,
• Luan A. Martinho,
• Lucinda J. Bessa,
• Andreanne G. Vasconcelos,
• Alexandra Plácido,
• Alex L. Pereira,
• José R. S. A. Leite and
• Angelo H. L. Machado

Beilstein J. Org. Chem. 2019, 15, 2544–2551, doi:10.3762/bjoc.15.247

• new C–S bond. The configuration of the double bond could be assigned as Z for all compounds due to the 1H,1H-NOESY correlations between the C3 hydrogen and the NH hydrogen of the amino acid residue attached to the adduct residue. The IR spectra of analogues 9 were quite similar (Supporting Information

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• with the nucleophilic aromatic ring in a Friedel–Crafts alkylation process, thus incorporating the carbon atom in a formal C(sp2)–H/C(sp3)–H cross-dehydrogenative coupling. Finally, an oxidation of sulfide 7 to sulfoxide 8 and the subsequent attack of amide 2 with cleavage of the C–S bond and formation

Degenerative xanthate transfer to olefins under visible-light photocatalysis

• Atsushi Kaga,
• Xiangyang Wu,
• Joel Yi Jie Lim,
• Hirohito Hayashi,
• Yunpeng Lu,
• Edwin K. L. Yeow and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2018, 14, 3047–3058, doi:10.3762/bjoc.14.283

• previously been ascribed to the absorption of the xanthic acid radical formed plausibly from homolytic C–S bond cleavage of the short-lived triplet state of xanthate 1a [22]. The ns-TA spectra of photocatalyst 8 (25 μM) in the presence of xanthate 1a (40 mM) in degassed DMSO at various delay times are shown

• absorption spectroscopy study of xanthate 1a was conducted (Figure 3). The UV–vis absorption spectrum of 1a (1 mM in DMSO) showed absorption bands at 340–390 nm assigned to the n→π* electronic transition of the C=S bond as a characteristic peak of thiocarbonyl containing compounds [56]. In fact, the reaction

• of 1a and 2a under 365 nm UV lamp irradiation without a photocatalyst delivered product 3aa in 75% yield (Table 1, entry 9). This indicates the excitation of xanthate 1a through an n→π* electronic transition of the C=S bond is in operation in the UV irradiation process. The involvement of a radical

Synthesis of aryl sulfides via radical–radical cross coupling of electron-rich arenes using visible light photoredox catalysis

• Amrita Das,
• Mitasree Maity,
• Simon Malcherek,
• Burkhard König and
• Julia Rehbein

Beilstein J. Org. Chem. 2018, 14, 2520–2528, doi:10.3762/bjoc.14.228

• , antidepressant or antileukotriene agents (Figure 1). Three of the five most selling drugs in 2015 were organosulfur compounds. The majority of methods for C–S bond synthesis use transition metal-catalyzed cross coupling of thiols and their derivatives with organohalides [4][5][6], arylboronic acids [7], aryl

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• compatibility. Hajra et al. have reported the direct C–H thiocyanation of substituted imidazo[1,2-a]pyridines, using ammonium thiocyanate, in combination with Eosin Y under irradiation by blue LEDs (Scheme 9) [52]. This is another photoredox example of C–S bond formation, in this case to a highly versatile

Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium

• Alphonse Fiebor,
• Richard Tia,
• Banothile C. E. Makhubela and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160

• attached to the sulfur atom are pointing away from the plane of the metal centre such that the thioether angles are 100.2(2)° and 102.72(2)° corresponding to C(6)–S(1)–C(9) and C(7)–S(2)–C(13), respectively. The thioether C–S bond lengths obtained are 1.808(4) Å and 1.816(4) Å for S(1)–C(6) and S(2)–C(7

A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

• Anna Czarnecka,
• Emilia Kowalska,
• Agnieszka Bodzioch,
• Joanna Skalik,
• Marek Koprowski,
• Krzysztof Owsianik and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105

• -coupling reactions of substrates containing an 1,3-dithiane moiety are feasible, like in the case of the 2-arylation of 2-aryl-substituted 1,3-dithianes. However, in the case of 2-benzyl-substituted 1,3-dithianes, a tandem elimination/1,3-dithiane ring opening followed by a Pd-catalyzed C−S bond formation

• are to be expected. This task is additionally difficult to accomplish due to a chemical similarity of oxygen and sulfur, two neighboring heteroatoms from the main group VI of the periodic table. A longer atomic radius of sulfur than oxygen should make the C–S bond weaker and more reactive than the C–O

Stereoselective nucleophilic addition reactions to cyclic N-acyliminium ions using the indirect cation pool method: Elucidation of stereoselectivity by spectroscopic conformational analysis and DFT calculations

• Koichi Mitsudo,
• Junya Yamamoto,
• Tomoya Akagi,
• Atsuhiro Yamashita,
• Masahiro Haisa,
• Kazuki Yoshioka,
• Hiroki Mandai,
• Koji Ueoka,
• Christian Hempel,
• Jun-ichi Yoshida and
• Seiji Suga

Beilstein J. Org. Chem. 2018, 14, 1192–1202, doi:10.3762/bjoc.14.100

• very efficiently yield carbon–carbon bond-formation products. In addition, this research lead to the development of an indirect cation pool method that enables the creation of the cation pool by reacting a cation precursor having a C–S bond with an electrochemically generated ArS(ArSSAr)+ as the cation

The selective electrochemical fluorination of S-alkyl benzothioate and its derivatives

• Shunsuke Kuribayashi,
• Tomoyuki Kurioka,
• Shinsuke Inagi,
• Ho-Jung Lu,
• Biing-Jiun Uang and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2018, 14, 389–396, doi:10.3762/bjoc.14.27

• equiv, the product yield was also increased from 55% to 67% (Table 1, entry 10). However, in this case, C–S bond cleavage also took place to form benzoyl fluoride (3a) as a byproduct in considerable amounts. In all cases, no fluorination at the phenyl group took place. Then, this anodic fluorination was

• (Scheme 2). We next also carried out the anodic fluorination of a cyclic benzothioate namely benzothiophenone 1l. In this case, the fluorination took place predominantly at the benzylic position to afford the fluorinated product 2l in 60% isolated yield (Scheme 3). With this substrate, neither C–S bond

• the other hand, a minor pathway involves a C–S bond cleavage to form benzoyl fluoride as is observed in the case of the anodic oxidation of S-aryl benzothioates [23]. In the case of S-alkyl benzothioates bearing a carboxyl group at the γ and δ-position with respect to the sulfur atom, after generation

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

• –S bonds were developed and already excellently reviewed, including nucleophilic substitution reactions between S-nucleophiles and organic electrophiles, metal-catalyzed C–S bond formations and organocatalytic or enzymatic approaches [15][16][18][20][21][22]. This review provides a brief overview

• disulfide, thioamide derivatives and sulfides Disulfides and thiosulfates Sulfoxides Sulfinic acids, sulfinate salts and sulfinamides Sulfonyl halides, sulfonyl hydrazines, thionyl chloride and sulfur dioxide C–S bond formations initiated by irradiation with light of wavelengths shorter than 380 nm or by

• radical initiators as well as photocatalytic reactions, where sulfur-containing substrates act as a sacrificial agent are not discussed in this review [23][24][25][26][27][28]. Review Thiols Formation of sulfides and sulfoxides A large number of photocatalytic C–S bond-forming methods report the

Intramolecular glycosylation

• Xiao G. Jia and
• Alexei V. Demchenko

Beilstein J. Org. Chem. 2017, 13, 2028–2048, doi:10.3762/bjoc.13.201

• would form as the key intermediate. Upon dissociation of the anomeric C–S bond of the sulfonium intermediate 102, an oxygen nucleophile on the boronate ester would attack the C-1 center on the opposite side resulting in 103 with good stereoselection (Scheme 23). Initial trials with 3-methylbenzyl

Transition-metal-free synthesis of 3-sulfenylated chromones via KIO₃-catalyzed radical C(sp²)–H sulfenylation

• Yanhui Guo,
• Shanshan Zhong,
• Li Wei and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2017, 13, 2017–2022, doi:10.3762/bjoc.13.199

• chromones via domino chromone ring construction and C(sp2)–H bond sulfenylation have been achieved under transition-metal-free conditions by using KIO3 as the only catalyst. Keywords: C–H sulfenylation; chromones; domino reaction; free-radical; transition-metal-free; Introduction The C–S bond-forming

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• -ring forming cycloetherifications, which gave a straightforward access to tocopherols with very high selectivities [126]. α-Thioetherifications The catalytic stereoselective C–S bond formation in the α-position of prochiral nucleophiles became the topic of broader interest rather recently [127][128

• ][129][130][131][132][133][134]. Again, different catalytic strategies have been successfully employed to achieve these transformations and asymmetric phase-transfer catalysis is one powerful option to control the configuration of the newly installed C–S bond. The first reports describing the use of

Phenylsilane as an effective desulfinylation reagent

• Wanda H. Midura,
• Aneta Rzewnicka and
• Jerzy A. Krysiak

Beilstein J. Org. Chem. 2017, 13, 1513–1517, doi:10.3762/bjoc.13.150

• sulfide substituents, under these conditions, reduction of the carbonyl group occurred leading to the corresponding alcohols (18 [25], 22) as the only products in high yield. It means that attack on sulfur is not connected with the presence of a C–S bond but a sulfinyl substituent is required. In a former

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• has not been reported. In this review, a brief overview is given of the recent advances in synthetic strategies for both phenols and aryl thiols. Keywords: aryl thiol; C–O bond; C–S bond; phenol; transition metal; Introduction Phenols and aryl thiols serve as both important intermediates in organic

• -catalyzed Ullmann-type coupling reaction has emerged as an effective method, allowing the synthesis of phenols and aryl thiols from aryl halides through C–O and C–S bond formation, respectively [5][6][7]. Very recently, the C–H activation has made revolutionary advances in organic synthesis because it

• converted in situ to aryl thiols through C–S bond cleavage by an intramolecular nucleophilic substitution. The protocol tolerated a broad range of functional groups such as amino, hydroxy, trifluoromethyl, ester, carboxy and formyl groups. As described above, although it seems more difficult to develop an

Dimerization reactions of aryl selenophen-2-yl-substituted thiocarbonyl S-methanides as diradical processes: a computational study

• Michael L. McKee,
• Grzegorz Mlostoń,
• Katarzyna Urbaniak and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 410–416, doi:10.3762/bjoc.13.44

• processes have not been studied in detail yet. Whereas the formation of the 1,3-dithiolane 4 can be explained via a concerted [2 + 3] cycloaddition of 1 as a 1,3-dipole with the activated C=S bond of 1, the dimerization leading to 5 seems to occur stepwise via an intermediate stabilized 1,6-diradical 6. In

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

• from I followed by electron delocalization and the overall formation of cyclohexyl isothiocyanate (4) via C–S bond cleavage and the formation of quinazoline thiol anion II having a negative charge concerted on the nitrogen atom. The protonated cyclohexylamine in the previous step will transfer this

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

• products of the [3 + 2]-cycloaddition of the diazo dipole onto the C=S bond. The latter decompose only at higher temperature (ca. −40 °C) to generate thiocarbonyl S-isopropanide. In the absence of the starting thioketone, the corresponding thiiranes and/or ethene derivatives, formed from them via

Trifluoromethyl-substituted tetrathiafulvalenes

• Olivier Jeannin,
• Frédéric Barrière and
• Marc Fourmigué

Beilstein J. Org. Chem. 2015, 11, 647–658, doi:10.3762/bjoc.11.73

• EWG-based LUMO, also observed in primary and secondary amides [10]. Another consequence of the contribution of the B form is the shortening of the C–S bond opposite to the EWG, experimentally observed in the structures of such molecules. More recently, we have reported another series of TTFs

• conformation with one fluorine atoms in the TTF mean plane, away from the other substituent. Bond lengths and angles are in the expected range. A dissymmetry of the C–S bonds (b, b′ in Table 4) in the dithiole ring bearing the different EWG is observed, with in both cases a shortening of the C−S bond close to

• shortening affects the C−S bond closest to the CF3 group demonstrates unambiguously that the mesomeric electron-withdrawing effect of the CN or CO2Me groups is indeed stronger than that of CF3. A similar effect is also observed on the structure of the symmetrical TTF 4bc, which was obtained as symmetrical

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

• demonstrated that diazoacetylacetone, even at room temperature, easily reacts with Ph2C=S, giving rise to the formation of 1,3-oxathiole derivatives [14][15], which are considered to be the typical final products of the 1,3-dipolar cycloaddition of diazoketones to the C=S bond [16][17][18]. In this regard, we

• reaction of 1 with the C=S bond of thioketone 2b (step 1) is followed by the decomposition of the intermediate 1,3,4-thiadiazoline 6' (step 2) giving rise to thiocarbonyl ylide 7'. The latter undergoes competitive 1,5- or 1,3-electrocylizations (step 3). Considering that thiadiazolines with bulky

• case of thioketone 2b, all calculations were performed for the gas phase. Reactions with thiobenzophenone (2a) By comparison with the literature data [16][17][18], one can assume that the multistep reactions of DDC 1a–d and thione 2a are initiated by 1,3-cycloaddition of the diazogroup with the C=S

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

• in the solution, and consequently the C–S bond cleavage seems to take place more favorably than a deprotonation. A similar effect on the suppression of defluorination of CF3-enolate anion in the presence of a large amount of fluoride ions has been reported [38]. On the other hand, it is known that

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• warming breaks the C–S bond and allowed the regeneration of the N-acyliminium ion in a new solution containing the desired nucleophile interceptor to immediately react with the N-acyliminium ion as it is released from its thiomaleimide tag (Figure 3). A micromixer has been used to generate an N