Thia- and selenaheterocycles by a four-component reaction using elemental sulfur and selenium

Abstract

The course of the four-component reactions of (2-benzimidazolyl) acetonitrile, carbondisulfide, isothiocyanate, and sulfur and selenium, respectively, is quite different. Whereas in the case of sulfur a tetracyclic [1,3]thiazolo[4′,5′:4,5]pyrimido[1,6-a]benzimidazol-2(3H)-thione is formed, a zwitterionic 7-(benzimidazolium-2-yl)-[1,2]thiaselenolo[2,3-b][1,2,4]thiaselenazole-6-thiolate (an azaselenadithiapentalene) is the product in the case of selenium. The structures of the products have been established by X-ray crystallography, and reaction mechanisms for their formation are proposed.

Keywords:

• Four-component reactions
• Isoselenocyanates
• Isothiocyanates
• Selenaheterocycles
• Thiaheterocycles

Acknowledgements

We thank the analytical services of our institute for spectra and analyses, and the Swiss National Science Foundation and F. Hoffmann-La Roche AG, Basel, for financial support.

Notes

∗CCDC-258493-258494 contain the spplementary crystallographic data for this paper. These data can be obtained free of charghe from the Cambridge Crystallographic Data Centre via http://www.ccdc.cam.ac.uk/data_request/cif.