Tertiary amine-S2Cl2 chemistry: Interception of reaction intermediates

The reaction of N-(2-chloroethyl)diisopropylamine 1a with S2Cl2 allows the selective one-pot preparation of the tricyclic 4-(2-chloroethyl)bisdithiolothiazines 8 and 9 or, by addition of phosphorus pentasulfide at a late stage of the reaction, of the dithiolothiazine 6b characterised by X-ray crystallography; the chloroethyl derivative 8 is also obtained from (2-diisopropylamino)ethanethiol 1b and its disulfide 1c and S2Cl2, in a rare conversion of a thiol or disulfide into the corresponding chloro compound.