Olefin synthesis by two-fold extrusion processes. Part 3. Synthesis and properties of hindered selenoketones (selones)

Monomeric selenoketones (selones) have been prepared from di-t-butyl ketone and (–)-1,3,3-trimethylnorbornan-2-one through heating their triphenylphosphoranylidenehydrazones with selenium. Although selones show greater reactivity towards diazo-compounds than thiones it was still not possible to prepare the elusive tetra-t-butylethylene. However, (–)-1,1′,3,3,3′,3′-hexamethyl-2,2′-binorbornylidene, which is a ‘tied back’ tetra-t-butylethylene, was obtained without difficulty and is stable to oxygen.The chemistry of selones has been briefly explored and compared with that of thiones. An improved preparation of di-t-butylketen is reported.