Conversion of N-Alkyldiisopropylamines into N,N-Bis(5-chloro-3-oxo[1,2]dithiol-4-yl)amines.

Triisopropylamine 1a and S2Cl2, in the presence of DABCO and formic acid, give the bicyclic amine 2a, and its N-dealkylated product 3, rather than the tricyclic bisdithiolothiazine system 7 produced by Hunig’s base 1b. However, when S2Cl2 is in molar excess over DABCO, Hunig’s base and related N-alkyldiisopropylamines 1c–g also give the analogous bicyclic compounds 2b–g together with the tricyclic compounds 7b–g. The N-benzyl compound 2c is debenzylated quantitatively to the secondary amine 3 by sulfuric acid. X-Ray crystallography of N,N-bis(dithiolyl)ethylamine 2b shows the two dithiole rings to be steeply inclined to each other (85°) and the geometry at nitrogen to be slightly pyramidal. The crystal packing is dominated by S· · ·O electrostatic and weak CO· · ·Cl charge-transfer interactions.