α,β-Unsaturated thiocarbonyl S-sulfides (thiosulfines). Their generation, intramolecular trapping by a non-activated CC dipolarophile via[5 + 2] cycloaddition and trans-sulfurization ability

Saito, Takao; Nagashima, Masumi; Karakasa, Takayuki; Motoki, Shinichi

doi:10.1039/c39920000411

Cited by 20 publications

(4 citation statements)

References 13 publications

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“…, whereas the formation of reactive thiocarbonyl S-sul®des from thioketones and S 8 needs higher temperatures (e.g. Saito, Nagashima et al, 1992;Saito, Shundo et al, 1992;Okuma et al, 1993) or the presence of sodium benzenethiolate as a catalyst . In the case of adamantanethione, the corresponding 1,2,4-trithiolane was formed on treatment with silica gel in dichloromethane (Linden et al, 2002).…”

Section: Commentmentioning

confidence: 99%

Four bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)oligosulfanes

et al. 2002

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The four oligosulfanes, bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)disulfane, C(16)H(24)Cl(2)O(2)S(2), (III), 1,3-bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)trisulfane, C(16)H(24)Cl(2)O(2)S(3), (V), 1,4-bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)tetrasulfane, C(16)H(24)Cl(2)O(2)S(4), (VII), and 1,6-bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)hexasulfane, C(16)H(24)Cl(2)O(2)S(6), (VIII), all have similar geometric parameters, with the C-C bond lengths involving the chloro-substituted cyclobutanyl C atom being elongated to about 1.59 A. There are two molecules in the asymmetric units of the tri- and tetrasulfanes, and the molecules in the latter compound have local C(2) symmetry. The molecule of the hexasulfane has crystallographic C(2) symmetry. Most of the cyclobutanyl rings are not perfectly planar and have slight but varying degrees of distortion towards a flattened tetrahedron. The polysulfane chain in each structure has a helical conformation, with each additional S atom in the chain adding approximately one quarter of a turn to the helix.

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Section: Commentmentioning

confidence: 99%

Four bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)oligosulfanes

et al. 2002

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“…Correctly, the fraction containing only the monomeric form is often described as ‘thiochalcone fraction’ [ 25 , 27 ]. As mentioned in the ‘Introduction’, the single experiment reporting sulfurization of a rather complex, in situ-generated thiochalcone relates to harsh reaction conditions with heating of the reaction mixture in boiling xylene [ 17 ].…”

Section: Resultsmentioning

confidence: 99%

“… Reaction of thiochalcones 11 with sulfur yielding 1,2-dithiepanes 12 via intramolecular [5+2]-cycloaddition of intermediate thiocarbonyl S -sulfides 4c (ref. [ 17 ]). …”

Section: Figures Schemes and Tablesmentioning

confidence: 99%

“…In an earlier publication, however, sulfurization of rather complex thiochalcones 11 , prepared in situ from corresponding ketones 10 , was carried out in non-polar xylene by treatment with S 8 . These reactions led to the polycyclic products 12 , which were formed as minor products, exclusively [ 17 ] ( Scheme 3 ). The formation of the latter heterocycles was explained via a multi-step mechanism with the respective α,β-unsaturated thiocarbonyl S -sulfides 4c as the reactive intermediates in the postulated intramolecular [5+2]-cycloaddition reactions.…”

Section: Introductionmentioning

confidence: 99%

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The Fluoride Anion-Catalyzed Sulfurization of Thioketones with Elemental Sulfur Leading to Sulfur-Rich Heterocycles: First Sulfurization of Thiochalcones

et al. 2021

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Fluoride anion was demonstrated as a superior activator of elemental sulfur (S8) to perform sulfurization of thioketones leading to diverse sulfur-rich heterocycles. Due to solubility problems, reactions must be carried out either in THF using tetrabutylammonium fluoride (TBAF) or in DMF using cesium fluoride (CsF), respectively. The reactive sulfurizing reagents are in situ generated, nucleophilic fluoropolysulfide anions FS(8−x)−, which react with the C=S bond according to the carbophilic addition mode. Dithiiranes formed thereby, existing in an equilibrium with the ring-opened form (diradicals/zwitterions) are key-intermediates, which undergo either a step-wise dimerization to afford 1,2,4,5-tetrathianes or an intramolecular insertion, leading in the case of thioxo derivatives of 2,2,4,4-tetramethylcyclobutane-1,3-dione to ring enlarged products. In reactions catalyzed by TBAF, water bounded to fluoride anion via H-bridges and forming thereby its stable hydrates is involved in secondary reactions leading, e.g., in the case of 2,2,4,4-tetramethyl-3-thioxocyclobutanone to the formation of some unexpected products such as the ring enlarged dithiolactone and ring-opened dithiocarboxylate. In contrast to thioketones, the fluoride anion catalyzed sulfurization of their α,β-unsaturated analogues, i.e., thiochalcones is slow and inefficient. However, an alternative protocol with triphenylphosphine (PPh3) applied as a catalyst, offers an attractive approach to the synthesis of 3H-1,2-dithioles via 1,5-dipolar electrocyclization of the in situ-generated α,β-unsaturated thiocabonyl S-sulfides. All reactions occur under mild conditions and can be considered as attractive methods for the preparation of sulfur rich heterocycles with diverse ring-size.

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Intramolecular Hetero Diels−Alder Reactions of α,α’-Dioxosulfines − A New Access to the [3.3.1]-Bicyclic Skeleton

et al. 2000

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Simple transformations of tert‐butylthio‐substituted 1,4‐oxathiin permitted the preparation of oxathiin S‐oxides. These in turn were suitable precursors of corresponding α,α′‐dioxosulfine dienes with tethered internal electron‐rich double bonds. Examining the synthetic utility of these sulfines, we observed either hydrolysis or intramolecular cycloaddition, depending on the distance between the reactive centres and the substitution on the double bond. Bicyclic derivatives with a [3.3.1] skeleton and an sp2 bridgehead carbon were obtained from the cycloadditions.

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α,β-Unsaturated thiocarbonyl S-sulfides (thiosulfines). Their generation, intramolecular trapping by a non-activated CC dipolarophile via[5 + 2] cycloaddition and trans-sulfurization ability

Cited by 20 publications

References 13 publications

Four bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)oligosulfanes

Four bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)oligosulfanes

The Fluoride Anion-Catalyzed Sulfurization of Thioketones with Elemental Sulfur Leading to Sulfur-Rich Heterocycles: First Sulfurization of Thiochalcones

Intramolecular Hetero Diels−Alder Reactions of α,α’-Dioxosulfines − A New Access to the [3.3.1]-Bicyclic Skeleton

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