The
reaction pathway of silyloxypyrone-based (5 + 2)
cycloadditions
was determined to be extremely dependent on the nature of the dipolarophile.
Neutral alkenes were the least reactive, whereas both electron-deficient
and electron-rich dipolarophiles were more reactive, thus providing
evidence for ambident oxidopyrylium intermediates. Qualitative rate
studies, Hammett linear free energy relationships, and theoretical
calculations combined to provide evidence for a spectrum of reactivity
that passes through the borderlands of concerted and stepwise.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.