1.3- Dithioles 2-alkoxy- from

Recently it has been reported that a-thio derivatives of enamines and enol ethers form 5-amino- or 5-alkoxy-l,2-dithiole-3-thiones (127a, b) by reaction with carbon disulfide (80ZOR13). Spiran compounds (128) are also formed from suitable substrates. The reaction has some similarities to an enamine synthesis below <67AG(E)294). 

Alkyl- and aryl-1,2-dithiol-3-ones (3a) are made by ring synthesis from unsaturated esters (B-66MI43100) and alkylation of these affords 3-alkoxy-l,2-dithiolylium salts (35b). The parent (3a R1 = R2 = H) is best made from the thione (3b) by treatment with mercury(II) acetate (63CB2702). 

Alkoxy-l,3-dithioles can serve as generators of carbenes. Thus, reaction of (161) with trichloroacetic acid produces a carbene (162) which in the presence of aromatic aldehydes forms the 1,3-dithiole derivatives (163) (Scheme 34) <80PJC717>. Quite similarly, from (162) and succinimide the imide (164) is obtained <80PJC145>. 

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