  Achieving control over chemical reaction's rate and stereoselectivity
realizes one of the Holy Grails in chemistry that can revolutionize chemical
and pharmaceutical industries. Strong light-matter interaction in optical or
nanoplasmonic cavities might provide the knob to reach such control. In this
work, we demonstrate the catalytic and selectivity control of an optical cavity
for two selected Diels-Alder cycloaddition reactions using the quantum
electrodynamics coupled cluster (QED-CC) method. Herein, we find that by
changing the molecular orientation with respect to the polarization of the
cavity mode the reactions can be significantly inhibited or selectively
enhanced to produce major endo or exo products on demand. This work highlights
the potential of utilizing quantum vacuum fluctuations of an optical cavity to
modulate the rate of Diels-Alder cycloaddition reactions and to achieve
stereoselectivity in a practical and non-intrusive way. We expect that the
present findings will be applicable to a larger set of relevant click chemical
reactions under strong light-matter coupling conditions.
