Vanadium-Mediated Carbon Isotope Exchange of Terminal Alkenes

The incorporation of carbon isotopes into bioactive compounds
is
of great importance in chemistry, biology, and medicine. Especially
valuable are catalytic procedures that rely on a limited collection
of available labeled materials. Recently we introduced a conceptually
novel solution to carbon isotope exchange (CIE) for terminal olefins
based on the preference of V alkylidenes for degenerate metathesis.
However, the previous report utilized a V catalyst that suffered from
functional group tolerance due to the high electrophilicity of the
V center, making it impractical for biological compounds. Herein,
we utilized V catalysts containing electron-donating groups to overcome
those challenges. We utilize isotopically labeled substituted styrene
as a labeled 13CH2 moiety source, prepared
from 13C-labeled iodomethane. The isotope source can be
easily removed from the reaction mixture, recovered, and reused. A
diverse range of terminal alkenes, including bioactive molecules,
were tested to showcase the capabilities and limitations of the developed
method.