Highly Stereoselective Synthesis of ( E )‐(2‐Bromovinyl)selenoxides Using Solid Calcium Carbide as a Substitute for Gaseous Acetylene

A concise method for the synthesis of ( E )‐(2‐bromovinyl)arylselenoxides using calcium carbide as a solid alkyne source, tetrabutylammonium tribromide as a solid bromine source, benzoyl peroxide as an oxidant and an initiator, and 1,2‐diaryldiselenides as starting materials through a one‐pot procedure is described. The target products were obtained via cascade reactions involving the simultaneous formation of SeC, SeO, and CBr bonds. The salient features for this protocol are the use of inexpensive and easy‐to‐handle solid alkyne source instead of flammable and explosive gaseous acetylene, the use of safe and convenient solid bromine source instead of toxic and corrosive liquid bromine, high stereoselectivity, transition metal‐free conditions, wide functional tolerance, satisfactory yield, and simple workup procedures. The reactions can also be carried out on a gram scale.