<p>C-H bond activation has been established as an attractive strategy to
access axially chiral biaryls, and the most straightforward method is direct
C-H arylation of arenes. However, the arylating source has been limited to
several classes of reactive and bulky reagents. Reported herein is
rhodium-catalyzed 1:2 coupling of diarylphosphinic amides and diarylacetylenes
for enantio- and diastereoselective construction of biaryls with both central
and axial chirality. This twofold C-H activation reaction stays contrast to the
previously explored Miura-Satoh type 1:2 coupling of arenes and alkynes in
terms of chemoselectivity and proceeded under mild conditions with the alkyne
acting as a rare arylating reagent. Both C-H activation events are
stereo-determining and are under catalyst control, with the 2<sup>nd</sup> C-H
activation being diastereo-determining in a remote fashion. Analysis of the
stereochemistries of the major and side products suggests moderated
enantioselectivity of the initial C-H activation-desymmetrization process.
However, the minor stereoisomeric (<i>R</i>) intermediate is consumed more
readily in undesired protonolysis, eventually resulting in high enantio- and
diastereoselectivity of the major product.</p>
Conversion of two stereocenters to one or two chiral axes: atroposelective synthesis of 2,3-diarylbenzoindoles
