1.2- Dithiolylium ions aromaticity

Methyl-l,2-dithiolyliums react with aldehydes to give styryl derivatives and with DMF to give Vilsmeier salts, and on nitrosation form the bicyclic products 598. 2-Alkyl groups in 1,3-dithiolylium ions also react with aromatic aldehydes to give 599 and with DMF to give 600. 

Dithiole is not a cyclic conjugated system. However, the 1,2-dithiolylium ions derived from it are aromatic. For instance, the corresponding salts are obtained from 1,3-dicarbonyl compounds and disul-fane in acid solution ... 

The 1,3-dithiolylium (also named 1,3-dithiolium) ions 1, which can be formally derived from 1,3-ditholes 4 by abstraction of a hydride anion, possess a bn-electron aromatic system and can be represented by canonical stmctures la-le. 

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