Quantum Mechanical Tunneling in Homodienyl Sigmatropic [1,5]-Hydrogen Shifts of (Hydroxymethyl)styrylcyclopropanes

The strong temperature dependence of the deuterium kinetic isotope effect observed for homodienyl [1,5]-hydrogen migration of [hydroxy (D)methyl] styrylcyclopropanes (1c,d) in hexane solvent is suggestive of a significant tunnelling contribution to the mechanism. While the hydroxy substituent at the migration origin appears to influence the thermolytic behaviour of these molecules, attempts to promote oxy anionic homodienyl rearrangement in the isotopically natural compounds (1a,b) at low temperature were unsuccessful.