Synthesis of 2-Fluoro-3-phenylthio-1,3-butadiene and 2-Trifluoromethyl-3-phenylthio-1,3-butadiene and Their Reactivities toward Various Dienophiles

A general approach for the synthesis of novel 2-fluoro-3-phenylthio-1,3-butadiene (8) and 2-trifluoromethyl-3-phenylthio-1,3-butadiene (9) from monobromoalkene and dibromoalkenes has been developed. Subsequent Diels-Alder reactions of these dienes with symmetrical and unsymmetrical dienophiles in the presence of Lewis acids gave a variety of fluorinated six-membered carbocycles in moderate to high yields.