Switchable Reactivity of Cyclopropane Diesters toward (3 + 3) and (3 + 2) Cycloadditions with Benzoquinone Esters

Herein,
we describe an unprecedented (3 + 3) cycloaddition reaction
of the donor–acceptor cyclopropanes with quinone esters toward
the construction of chroman scaffolds in moderate to good yields.
Interestingly, the strategy is also adjustable toward a (3 + 2) cycloaddition
by just switching the Lewis acid to furnish benzofuran scaffolds.
Based on the choice of Lewis acid used, the same set of precursors
has been used to deliver the benzopyran and benzofuran derivatives.