Synthesis and reaction of tricyclic tetrathiins and pentathiepins: novel formation of α-disulfines

Cyclic polysulfanes containing a norbornane skeleton (tetrathiins and pentathiepins) were synthesized by two methods. One is the sulfurization of camphor hydrazone with disulfur dichloride, and the other is the reaction of thiocamphor with disulfur dichloride. The reduction of tetrathiin with LiEt3BH gave the corresponding dithiol that further reacted with methyl iodide to afford the corresponding methyl sulfide. Reaction of tetrathiin with (Ph3P)2PdCl2 or NiBr2 resulted in the formation of the corresponding dithiolene metal complexes. Tetrathiins were stereoselectively oxidized by m-CPBA to afford the corresponding α-disulfines.