Isotope-Controlled Selectivity by Quantum Tunneling: Hydrogen Migration versus Ring Expansion in Cyclopropylmethylcarbenes Academic Article uri icon

abstract

  • Using the tunneling-controlled reactivity of cyclopropylmethylcar-bene, we demonstrate the viability of isotope-controlled selectivity (ICS), a novel non-classical control element of chemical reactivity where a molecular system with two conceivable products of tunneling exclusively produces one or the other, depending only on isotopic composition. Our multidimensional small-curvature tunneling (SCT) computations indicate that under cryogenic conditions, 1-methoxycyclopropylmethylcarbene shows rapid H-migration to 1-methoxy-1-vinylcyclopropane, whereas deuterium-substituted 1-methoxycyclopropyl-d3-methylcarbene undergoes ring expansion to 1-d3-methylcyclobutene. This predicted change in reactivity constitutes the first example of a kinetic isotope effect that discriminates between the formation of two products.

publication date

  • July 12, 2017