Reported herein is asymmetric [3+ +2] annulation of arylnitrones with different classes of alkynes catalyzed by chiral rhodium(III) complexes,w ith the nitrone acting as an electrophilic directing group.T hree classes of chiral indenes/ indenones have been effectively constructed, depending on the nature of the substrates.T he coupling system features mild reaction conditions,excellent enantioselectivity,and high atomeconomy.I np articular,t he coupling of N-benzylnitrones and different classes of sterically hindered alkynes afforded CÀCor CÀNatropochiral pentatomic biaryls with aC-centered pointchirality in excellent enantio-and diastereoselectivity (45 examples,a verage 95.6 %e e). These chiral center and axis are disposed in adistal fashion and they are constructed via two distinct migratory insertions that are stereo-determining and are under catalyst control.Scheme 1. Formationo fmultiple chiral elements via CÀHfunctionalization (DG = directing group, SDS = stereo-determining step).

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Reported herein is the efficient and atroposelective construction of two categories of C–N atropisomers via rhodium­(III)-catalyzed C–H activation of sulfoxonium ylides en route to [4+2] annulation with sterically hindered, electron-rich alkynes. This reaction proceeds with high regio- and enantioselectivity under redox-neutral conditions via a double-substrate activation strategy, providing a novel entry to C–N axially chiral 4-functionalized 1-naphthols.

Reported herein is the Rh­(III)-catalyzed annulation of N-unprotected 2-arylindoles with quinone monoacetals for the straightforward synthesis of [4,3,1]-bridged carbocycles with exclusive C(3) selectivity. Mechanistic studies, particularly deuterium-labeling experiments, suggest that the coupling likely proceeds via two-fold C–H activation with two-fold migratory insertion into the enone moieties.

N-N axially chiral biaryls represent a rarely explored class of atropisomers. Reported herein is construction of diverse classes of diaxially chiral biaryls containing N-N and C-N/C-C diaxes in distal positions in excellent enantioselectivity and diastereoselectivity. The N-N chiral axis in the products provides a handle toward solvent-driven diastereodivergence, as has been realized in the coupling of a large scope of benzamides and sterically hindered alkynes, affording diaxes in complementary diastereoselectivity. The diastereodivergence has been elucidated by computational studies which revealed that the hexafluoroisopropanol (HFIP) solvent molecule participated in an unusual manner as a solvent as well as a ligand and switched the sequence of two competing elementary steps, resulting in switch of the stereoselectivity of the alkyne insertion and inversion of the configuration of the C-C axis. Further cleavage of the N-directing group in the diaxial chiral products transforms the diastereodivergence to enantiodivergence.