Molecules (2021)
Update date:2022-08-04
Topics:
Bielinski, Dariusz M.
Heimgartner, Heinz
Mloston, Grzegorz
Urbaniak, Katarzyna
Wreczycki, Jakub
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.
View MoreGuilin Zhenda Bio-Tech Co., Ltd.
Contact:86-773-3568977
Address:-Yangtang shangshui industry park, Lingui county,
Taizhou Yousheng Chemical Co., Ltd.
website:http://www.youshengchem.com
Contact:+86-13957672369
Address:Sanshan Chemical Industrial Zone
Shanghai PuYi Chem-Tech Co.,Ltd.
Contact:+86-21-57687505-227
Address:3 Floor, Building 11, No 201 MinYi Road, Songjiang District, Shanghai 201612, China
Tianjin Tensing Fine Chemical Research Develop Centre
Contact:86-022-23718576,13032267585
Address:2-2-201,13 Guiyuan road,Huayuan Industry district,Tianjin,china
Geen Chemical Technology Co., Ltd
Contact:86-769-21660847
Address:1408, Yingfeng Commercial Center, Nancheng District
Doi:10.1002/prac.19933350311
(1993)Doi:10.1021/ie50476a032
(1949)Doi:10.1021/jo00340a010
(1982)Doi:10.1021/jo00340a020
(1982)Doi:10.1021/ic0493806
(2004)Doi:10.1016/S0040-4039(01)90555-6
(1981)