Herein,
we report the Pd(0)-catalyzed intermolecular asymmetric
dearomative [3 + 2] annulation of phenols with vinyl cyclopropanes
via in situ generated ortho-quinone methide intermediates.
A series of highly functionalized spiro-[5,6] bicycles which bear
three contiguous stereogenic centers including one all-carbon quaternary
were obtained with excellent stereoselectivities. Density functional
theory (DFT) calculations indicate that the reactions were controlled
by thermodynamics.
The
first catalytic enantioselective [3 + 2] cycloaddition reaction
between vinylcyclopropanes and alkenyl N-heteroarenes
in the presence of LiBr and a Pd(0)/SEGPHOS complex was developed.
LiBr plays a key role in improving the reactivity of alkenyl N-heteroarenes as a mild Lewis acid.
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