Ring‐Opening Reactions of 3,5‐Bis(methylthio)‐1,2‐dithiolium Salts with Cyclopentadienides

4‐Aryl‐substituted 3,5‐bis(methylthio)‐1,2‐dithiolium salts such as 1a react with metal cyclopentadienides 4 (M + =Tl, Li) mainly by cleavage of the S–S bond. A subsequent intramolecular Diels‐Alder addition of the ring‐opened structures 5/6 gives the tricyclic compounds 7a and 8a, b . Intramolecular condensation of 5 or 6 yields the cyclopenta[ b ]thiopyran 11a . With the 4‐unsubstituted 3,5‐bis(methylthio)‐1,2‐dithiolium salt 1b the intramolecular Diels‐Alder adducts 8c, d and 9a, 10a were isolated. 4‐Alkyl‐substituted 1,3‐bis(methylthio)‐1,2‐dithiolium salts such as 1c react with thallium cyclopentadienides 4 mainly by substitution at C‐3 leading to the formation of the 2,3‐dithiafulvalenes 12a, b . The reaction of these salts with lithium cyclopentadienides leads to S–S bond cleavage followed by an intramolecular condensation affording the cyclopenta[ b ]thiopyran 11b .