Synthesis of sulfur-rich 1,2-and 1,3-dithiolo disulfides and thiodesaurines from diisopropyl sulfide

The reaction of diisopropyl sulfide and S2Cl2 in chlorobenzene, in the presence of DABCO, gives 4-isopropylthio-5-isopropyldithio-1,2-dithiole-3-thione (1) and the dimeric 5,5‘-dithiobis(4-isopropylthio-1,2-dithiol-3-thione) (2). If the reaction is performed in the presence of diisopropyl disulfide at the last stage of the reaction, disulfide 1 is selectively obtained. Some interconversions between 1 and 2 under UV irradiation are described, and a coherent set of reaction pathways for the formation of 1 and 2 are proposed. Treatment of 1 with DMAD in benzene gives the 1:1 adduct 9 in high yield; analogously the bisdithiolo disulfide 2 gives the 1:2 adduct 10, a very sulfur-rich molecule. Treatment of 1 with 1.27 equiv of triphenylphosphine in dichloromethane gives 4,5-di(isopropylthio)-1,2-dithiole-3-thione (11), but the treatment of 1 with 2 equiv of Ph3P affords thiodesaurine 12 (Z + E isomers), which was converted into desaurines 14 and 15 by treatment with nitrile oxide 16.