Significant advances have been achieved for the construction of chiral skeletons containing 1,2,3-triazoles via transition-metal-catalyzed asymmetric azide–alkyne cycloaddition; however, most of them have been limited to terminal alkynes in the synthesis of central chirality via desymmetrization and dynamic/dynamic kinetic resolution. Enantioselective transition-metal-catalyzed azide-internal-alkyne cycloaddition is extremely limited. Moreover, the construction of a challenging five-membered (hetero)­biaryl axially chiral molecule via transition-metal-catalyzed asymmetric azide-internal-alkyne cycloaddition is still underexplored. Herein, we first report an atroposelective and atom-economical synthesis of axially chiral 1,4,5-trisubstituted 1,2,3-triazoles, directly acting as core chiral units of challenging five-membered atropisomers, via the enantioselective Rh-catalyzed azide–alkyne cycloaddition (E-RhAAC) of internal alkynes and azides. The reaction demonstrates excellent functional group tolerance, forging a variety of C–C axially chiral 1,2,3-triazoles under mild conditions with moderate to excellent yields (up to 99% yield) and generally high to excellent enantioselectivities (up to 99% ee) along with specific regiocontrol. The origin of regio- and enantioselectivity control is disclosed by density functional theory (DFT) calculations, providing new guidance for the facile construction of axially chiral compounds.

of main observation and conclusion An efficient NaBAr F 4 -catalyzed oxidative cyclization of readily available 1,5-and 1,6-diynes has been developed. Importantly, this transition metal-free oxidative catalysis proceeds via a presumable Lewis acid-catalyzed S N 2' pathway, which is distinct from the relevant oxidative rhodium and gold catalysis. This method leads to the facile and practical construction of a diverse range of synthetically useful γand δ-lactams in mostly good to excellent yields with broad substrate scope. Scheme 1 Known knowledge and conceptual advance of this contribution Results and DiscussionWe set out to screen different conditions for this reaction by Chin.

Herein, an I 2 -catalyzed unprecedented cycloisomerization of ynamides is developed, furnishing various functionalized bis(indole) derivatives in generally good to excellent yields with wide substrate scope and excellent atom-economy. This protocol not only represents the first molecular-iodine-catalyzed tandem complex alkyne cycloisomerizations, but also constitutes the first chemoselective cycloisomerization of tryptamine-ynamides involving distinctively different C-(sp 3 )À C(sp 3 ) bond cleavage and rearrangement. Moreover, chiral tetrahydropyridine frameworks containing two stereocenters are obtained with moderate to excellent diastereoselectivities and excellent enantioselectivities. Meanwhile, cycloisomerization and aromatization of ynamides produce pyrrolyl indoles with high efficiency enabled by I 2 . Additionally, control experiments and theoretical calculations reveal that this reaction probably undergoes a tandem 5-exo-dig cyclization/rearrangement process.

An efficient gold-catalyzed cascade cyclization of alkenyl diynes involving alkyne oxidation, carbene-alkyne metathesis and cyclopropanation has been developed, furnishing a series of tetracyclic γ-lactams bearing one quaternary carbon center and...