Synthesis of [1,3]Dithiole and Spiro[1,3]dithiole Thiopyran Derivatives of the [1,2]Dithiolo[1,4]thiazine Ring System

• Published in: Journal of organic chemistry 2002-09, Vol.67 (18), p.6439-6448
• Main Authors: Barriga, Susana, Fuertes, Pedro, Marcos, Carlos F, Rakitin, Oleg A, Torroba, Tomás
• Format: Article
• Language: English
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo020015a

We report the synthesis of some new polysulfur−nitrogen heterocycles by cycloaddition reactions to readily available tricyclic condensed 1,2-dithiole-3-thiones. Thus, treatment of bis[1,2]dithiolopyrrole ketothione 1 with diacyl acetylenes gave the bis-aducts 2a − d. On the other hand, cycloaddition of bis[1,2]dithiolo[1,4]thiazine ketothione 3 with 1 equiv of acyl or diacyl acetylenes gave [1,3]dithiolylidenyl[1,2]dithiolo[1,4]thiazines 4a − f in fair to high yields. Catalysis by scandium triflate was used in the reactions that implied the less reactive dipolarophiles. Treatment of 3 with 2 equiv of DBA gave the bis-aduct 5a, and reaction of 4c with DMAD gave the mixed bis-adduct 5b. Cyclic voltammetry of selected examples showed irreversible processes that were influenced by the electrochemical activity of peripheral groups bonded to the heterocyclic system.