Synthesis of Thienyl Thioethers and Thieno[3,2-b] thiophenes
Integrated Synthesis of Thienyl Thioethers and Thieno[3,2-b]thiophenes via 1-Benzothiophen-3(2H)-ones: Mitsudo, N. Habara, Y. Kobashi, Y. Kurimoto, H. Mandai, S. Suga
Synlett 2020, 31, DOI: 10.1055/s-0040-1707280
Functionalized thioethers incorporating benzothiophenyl residues are important chemicals in materials science and drug discovery. The synthesis of these compounds can present some challenges, including the use of harsh conditions – such as strong bases and high temperatures – and/or transition-metal-based catalysts, which can be expensive for large-scale reactions and can be poisoned by the presence of the sulfur atoms. Recently, the group of Professors Koichi Mitsudo and Seiji Suga from Okayama University (Japan) described an extremely simple, efficient and scalable method for accessing the title compounds, based on a tandem TfOH-promoted Friedel–Crafts cyclization followed by reaction of the resulting transient thienyl thioether with an arenethiol.
Professors Suga and Mitsudo said: “A one-pot and transition-metal-free procedure for the synthesis of thienyl thioethers via benzo[b]thiophen-3-one has been developed.”