Chalcogenospecific ZnSs ( TMEDA ) Synthesis of 1 , 2 - Se &

The compound (C5H5)2TiS5 has allowed the rational syntheses of many sulfur homoand heterocycles.' This reagent serves as a reliable source of the S52unit, thereby defining a route to cyclic compounds of the type cyclo-S5+, and related Se-S rings.2 The coproducts and starting reagents are fairly chemically inert thus minimizing nucleophile-induced rearrangements of unstable cyclic polysulfanes. Starting in the early 1980s, we reported a second generation of polychalcogen group transfer reagents based on titanocene complexes with altered polychalcogenide ligands. Representative species include 1,4-[(C5H5)2TiE212 (E = S,3 Se4 ), 1,5-[(CsH~)2TiS3]2? (C~H5)2TiS2SiMe2,~ (C5H5)2TiSzPSAr,7 and ( C ~ H ~ ) Z T ~ S ~ C R ~ . ~ Steudel and coworkers have made extensive use of these and related organotitanium reagents for the preparation of many novel heterocyclic compound^.^ Given the successes seen for titanocene compounds it is interesting to consider the development of reagents based on other metals which might, for example, deliver different types of polychalcogen groups. The present report describes the use of such a reagent that is noteworthy since (i) it is based on zinc, not titanium, (ii) it is very easily prepared, and (iii) it delivers