[3 + 2] Cycloaddition of thioformylium methylide with various arylidene-azolones in the synthesis of 7-thia-3-azaspiro[4.4]nonan-4-ones

• Daniil I. Rudik,
• Irina V. Tiushina,
• Anatoly I. Sokolov,
• Alexander Yu. Smirnov,
• Alexander R. Romanenko,
• Alexander A. Korlyukov,
• Andrey A. Mikhaylov and
• Mikhail S. Baranov

Beilstein J. Org. Chem. 2025, 21, 1791–1798, doi:10.3762/bjoc.21.141

• single either cis or trans stereoisomers, dependent on the heterocycle core used. Keywords: arylidene-azolones; cycloaddition; nitrogen heterocycles; sulfur heterocycles; thioformylium methylide; Introduction Spirocyclic derivatives of heterocycles occupy an important place in modern organic and

Ambident reactivity of enolizable 5-mercapto-1H-tetrazoles in trapping reactions with in situ-generated thiocarbonyl S-methanides derived from sterically crowded cycloaliphatic thioketones

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Marcin Palusiak,
• Heinz Heimgartner,
• Marta Denel-Bobrowska and
• Agnieszka B. Olejniczak

Beilstein J. Org. Chem. 2025, 21, 1508–1519, doi:10.3762/bjoc.21.113

• ]. Thiocarbonyl S-methanides (thiocarbonyl ylides) 1, which were first reported in the 1980s by R. Huisgen and co-workers contributed to a substantial extension of mechanistic interpretations of cycloaddition reactions and to rapid development of methods applied not only for the synthesis of sulfur heterocycles

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

• ‘dithiane-scaffolding’ is indicated on the structures of the final targets. Compared to the very accomplished 1,3-dithianes, not many other sulfur-heterocycles have been able to follow into the mainstream organic synthesis tool box. For example, 1,3-dithiolanes are underperforming as heterocyclic building

• alkylations. Herein, the lithiated sulfur-heterocycles act as a cis-vinyl anion equivalent, a strategy that was developed by Palumbo and co-workers. The method shows some complementarity to the more classical acetylene alkylations, followed by partial hydrogenation to the cis-olefin (see Scheme 10 and Scheme

Ferrocenyl-substituted tetrahydrothiophenes via formal [3 + 2]-cycloaddition reactions of ferrocenyl thioketones with donor–acceptor cyclopropanes

• Grzegorz Mlostoń,
• Mateusz Kowalczyk,
• André U. Augustin,
• Peter G. Jones and
• Daniel B. Werz

Beilstein J. Org. Chem. 2020, 16, 1288–1295, doi:10.3762/bjoc.16.109

• thioketones; sulfur heterocycles; tetrahydrothiophenes; Introduction Functionalized tetrahydrothiophenes constitute an important group of five-membered sulfur heterocycles; many of them, both chiral and achiral, with biotin as the best-known representative, form the key motif in numerous compounds of great

• the formal [4 + 3]-cycloaddition [10] (Scheme 2). In a series of our recent publications, ferrocenyl/aryl and ferrocenyl/alkyl thioketones were demonstrated to be attractive substrates for the preparation of six- and five-membered sulfur heterocycles via [4 + 2]- and [3 + 2]-cycloadditions

• used with no special precautions. In general, ferrocene has been considered as an ‘exceptional compound’ [16][17] and in our hands ferrocenyl-functionalized sulfur heterocycles, e.g., thiiranes and 1,3-dithiolanes, have found applications for the synthesis of compounds relevant for medicinal [18] and

First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

• Grzegorz Mlostoń,
• Katarzyna Urbaniak,
• Paweł Urbaniak,
• Anna Marko,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156

• cycloadduct was isolated in 37% yield. Keywords: hetero-Diels–Alder reactions; quinone dyes; quinones; sulfur heterocycles; thiochalcones; Introduction Hetero-Diels–Alder reactions are considered to be a powerful methodology widely explored for the synthesis of six-membered heterocycles [1][2] with numerous

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• reaction has been extended by using a combination of 10 mol % of Cu(OTf)2, 12 mol % of 1,10-phenanthroline, and 2 equivalents of potassium phosphate, as reported by the group of Jiang (Scheme 30) [70]. Six- to eight-membered sulfur heterocycles 67 can thus be isolated from cyclic diaryl-λ3-iodanes. More

• metal-free alternative to the previous methods of formation of sulfur heterocycles 70 has been reported by using elemental sulfur in the presence of cesium carbonate (Scheme 32) [72]. The strategy can be extended to the synthesis of the cyclic selenium analogs 71 by utilizing elemental selenium and

• diaryl-λ3-iodanes. Synthesis of carbazoles and acridines from cyclic diaryl-λ3-iodanes. Synthesis of dibenzothiophenes from cyclic diaryl-λ3-iodanes. Synthesis of various sulfur heterocycles from cyclic diaryl-λ3-iodanes. Synthesis of dibenzothioheterocycles from cyclic diaryl-λ3-iodanes. Synthesis of

Synthesis of ferrocenyl-substituted 1,3-dithiolanes via [3 + 2]-cycloadditions of ferrocenyl hetaryl thioketones with thiocarbonyl S-methanides

• Grzegorz Mlostoń,
• Róża Hamera-Fałdyga,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2016, 12, 1421–1427, doi:10.3762/bjoc.12.136

• thioketones are remarkably stable in comparison with their aromatic analogues. Thus, the convenient access to thioketones 1 permitted their exploration for the synthesis of diverse sulfur heterocycles based on the reactivity of compounds containing a C=S group, known as ‘superdipolarophiles’ [2] or

An efficient synthesis of N-substituted 3-nitrothiophen-2-amines

• Sundaravel Vivek Kumar,
• Shanmugam Muthusubramanian,
• J. Carlos Menéndez and
• Subbu Perumal

Beilstein J. Org. Chem. 2015, 11, 1707–1712, doi:10.3762/bjoc.11.185

• transformation generates two C–C bonds in a single operation and presumably proceeds through a reaction sequence comprising 2-mercaptoacetaldehyde generation, nucleophilic carbonyl addition, annelation and elimination steps. Keywords: C–C bond generation; nitroarenes; nitroketene acetals; sulfur heterocycles

Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

• Grzegorz Mlostoń,
• Paulina Grzelak,
• Maciej Mikina,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2015, 11, 576–582, doi:10.3762/bjoc.11.63

• preparation of diverse sulfur heterocycles [1][2][3]. Studies performed by Huisgen and coworkers are of special importance and they resulted in the formulation of the name ‘superdipolarophiles’ for aromatic thioketones [4][5][6]. In addition, Sauer and coworkers called them ‘superdienophiles’ based on kinetic

Ruthenium-catalyzed C–H activation of thioxanthones

• Danny Wagner and
• Stefan Bräse

Beilstein J. Org. Chem. 2015, 11, 431–436, doi:10.3762/bjoc.11.49

• already in the pioneering work there are also examples using sulfur heterocycles such as thiophene derivatives [19]. Gratifyingly, the reaction of dimethyl-substituted thioxanthone 1b with the model olefin neohexene (3,3-dimethyl-1-butene, 4a) was successful and the product 1ba was obtained in 65% yield

Efficient Cu-catalyzed base-free C–S coupling under conventional and microwave heating. A simple access to S-heterocycles and sulfides

• Silvia M. Soria-Castro and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2013, 9, 467–475, doi:10.3762/bjoc.9.50

• disulfides and asymmetric diaryl sulfides in good yields. Keywords: catalysis; copper; cross-coupling; potassium thioacetate; sulfur heterocycles; Introduction Aromatic sulfur compounds including sulfides and heterocycles are relevant in chemical, pharmaceutical and materials industries [1][2][3]. As a

• , versatile, efficient and economically attractive procedure for the synthesis of sulfur heterocycles and a variety of sulfides with good yields. This one-pot methodology involves a cascade of reactions starting with a C–S bond formation by copper catalysis and followed by consecutive acyl transfers

Redox-active tetrathiafulvalene and dithiolene compounds derived from allylic 1,4-diol rearrangement products of disubstituted 1,3-dithiole derivatives

• Filipe Vilela,
• Peter J. Skabara,
• Christopher R. Mason,
• Thomas D. J. Westgate,
• Asun Luquin,
• Simon J. Coles and
• Michael B. Hursthouse

Beilstein J. Org. Chem. 2010, 6, 1002–1014, doi:10.3762/bjoc.6.113

• route for the synthesis and functionalisation of sulfur rich compounds including redox active compounds of TTFs, and a Ni dithiolene. Keywords: aldehydes; metal-coordination; rearrangement; sulfur heterocycles; tetrathiafulvalene; Introduction The search for novel structures derived from TTF has led