Selective Synthesis of (Z)-Chalcogenoenynes and (Z,Z)-1,4-bis-Chalcogenbuta-1,3-dienes Using PEG-400

We present here our results on the temperature controlled, selective hydrochalcogenation of 1,4-diorganyl-1,3-butadiynes with nucleophilic species of selenium, tellurium and sulfur generated in situ from the respective diaryl dichalcogenide and NaBH4. Using polyethylene glycol (PEG)-400 at 30 oC the (Z)-chalcogenoenynes are obtained and at 90 oC the (Z,Z)-bis-chalcogen-1,3-butadienes are produced in good to excellent yields. Alternatively to conventional oil bath heating, the use of microwave irradiation is also presented as an alternative energy source that provides the expected products in few minutes.