Addition of chalcogenolate anions to terminal alkynes using microwave and solvent-free conditions: easy access to bis-organochalcogen alkenes

We present here the reaction of diphenyl dichalcogenides (Se and Te) with propargyl alcohols using alumina supported sodium borohydride under solvent-free conditions. This efficient and improved method is general and furnishes the corresponding vinyl chalcogenide preferentially with a Z configuration. We also observed that when the same protocol was applied to phenyl acetylene, the (E)-bis-organochalcogen alkenes were obtained in good yields and high selectivity. The use of MW irradiation facilitates the procedure and accelerates the reaction. (c) 2005 Elsevier Ltd. All rights reserved.