Na2S-mediated synthesis of terminal alkynes from gem-dibromoalkenes

The Na2S-mediated facile synthesis of terminal alkynes from gem-dibromoalkenes, at 20/40 degrees C under open flask conditions has been developed. Various precursors derived from heteroaromatic/aromatic/aliphatic aldehydes were found compatible. The reaction is proposed to proceed through the Fritsch-Buttenberg-Wiechell (FBW) rearrangement involving the corresponding vinyl carbene. Using mild reaction conditions with inexpensive Na2S center dot 9H(2)O under air atmosphere has significant advantages over earlier routes.