1.2- Dithiol-3-ones reaction with Grignard reagents

Amino-4-aryl-l,2-dithiol-3-ones (69) and 5-(N-aryl-N-alkylamino)-4-chloro-l,2-dithiol-3-ones give rise to derivatives of thiomalonic acid (72) in the reaction with Grignard reagents.12u 3-lmino-l,2-dithioles (73) react in an analogous manner and give open chain thionoamides (74).12U,121d 122... 

The reaction of l,2-dithiol-3-ones with Grignard reagents has been studied in detail by Boberg and co-workers. Owing to resonance structures such as... 

Carbon nucleophiles may react at the sulfur-sulfur bond, or at C-3. Thus Grignard reagents react with monocyclic dithiol-3-ones (3a) and -3-imines (3c) at S-2 (74LA1261,73LA247). The product (84) of reaction of a Grignard reagent with benzo-1,2-dithiol-3-one (77a) (74T4113) could be alternately formed by attack at S-2, at C-3 or at C-5. Phosphonium ylides or other stabilized carbanions react at the 3-position of dithiol-ones... 

The products obtained by the action of bases and of Grignard reagents on 4,5-dichloro-l,2-dithiole-3-one include the 1,2,4-trithiolan (8), and 1,3-dithioles (9 R = COaMe or COSR). l,2-Dithiole-3-one is reported to give ring-opened trisulphides, e.g. RSSSCH=CHCOCl, with sulphenyl chlorides. Reactions of l,2-dithiole-3-ones with diphenyldiazomethane have also been investigated. ... 

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