Ene reactions of allylic derivatives of silicon, germanium, tin and lead with N-phenyltriazolinedione: the effect of varying the metal
The compounds Ph3MCH2CHCH2 and Ph3M[graphicomitted]H2)3(M = Si, Ge, Sn or Pb) have been treated with 4-phenyl-1,2,4-triazoline-3,5-dione, and the relative yields of the products of the M-ene reaction, of the H-ene reaction, and of the reaction involving cycloaddition with shift of the organometallic substituent, have been determined. The silicon compounds react principally by the H-ene process. The cycloaddition process is at a maximum (50% or 70%) with the germanium compounds, and the tin compounds show mainly the M-ene reaction, with some cycloaddition but no H-ene reaction. Triphenylprop-2-enylplumbane [and di(prop-2-enyl)mercury and phenyl(prop-2-enyl)mercury] show only the M-ene reaction.
In trimethyl(1,1-dimethylprop-2-enyl)silane, in which the H-ene reaction is blocked, only cyclo-addition with shift of the silyl group is observed.