Fritsch–Buttenberg–Wiechell rearrangement to alkynes from gem-dihaloalkenes with lanthanum metal

The first example of the FBW rearrangement using of lanthanum metal and a catalytic amount of iodine was disclosed. When gem-diiodo- and gem-dibromoalkenes were treated with lanthanum metal in the presence of a catalytic amount of iodine, the reductive dehalogenation of these compounds smoothly proceeded to produce the corresponding alkynes in moderate to good yields.

Graphical abstractThe first example of the FBW rearrangement using of lanthanum metal and a catalytic amount of iodine was disclosed. When gem-diiodo- and gem-dibromoalkenes were treated with lanthanum metal in the presence of a catalytic amount of iodine, the reductive dehalogenation of these compounds smoothly proceeded to produce the corresponding alkynes in moderate to good yields. Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Lanthanum metal as a reagent is directly used in organic synthesis. ► The first example of FBW rearrangement using of lanthanum metal is reported. ► The reductive dehalogenation of gem-dihaloalkenes gave the various alkynes.