Collect. Czech. Chem. Commun. 2006, 71, 650-666

Transformation of 1,2-Dithiole-3-thiones Into 1,6,6aλ4-Trithiapentalenes via Reaction with Bromoethanones

Richard Čmelíka,b and Pavel Pazderaa,*

a Department of Organic Chemistry, Faculty of Science, Masaryk University in Brno, Kotlářská 2, CZ-611 39 Brno, Czech Republic
b Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, Veveří 97, CZ-611 42 Brno, Czech Republic


We report the reactions of derivatives of 5-amino-3-thioxo-3H-1,2-dithiole-4-carboxylic acid 1 with bromoethanones and acylation agents. Two different routes were used to obtain the products, 3-(acylmethylidene)-3H-1,2-dithioles 4. These compounds were synthesized by acylation of compounds 1 on the amino group, followed by the reaction with bromoethanones and excess of triethylamine. Another method was based on the inverted order of the mentioned reaction steps and in absence of a base. The treatment of 4 with thionyl chloride gave new unsaturated fused lactones 13 whereas thionation led to desired 1,6,6aλ4-trithiapentalenes 5. The structures of products and the reaction mechanisms are discussed.

Keywords: 1,2-Dithiole-3-thiones; Sulfur heterocycles; Trithiapentalenes; Rearrangements; X-Ray diffraction; Reaction mechanism; Heterocyclizations.

References: 17 live references.