Brønsted acid-catalyzed asymmetric dearomatization for synthesis of chiral fused polycyclic enone and indoline scaffolds.

In the past two decades, substantial advances have been made on the asymmetric alkyne functionalization by the activation of inert alkynes. However, these asymmetric transformations have so far been mostly limited to transition metal catalysis, and chiral Brønsted acid-catalyzed examples are rarely explored. Here, we report a chiral Brønsted acid-catalyzed dearomatization reaction of phenol- and indole-tethered homopropargyl amines, allowing the practical and atom-economical synthesis of a diverse array of valuable fused polycyclic enones and indolines bearing a chiral quaternary carbon stereocenter and two contiguous stereogenic centers in moderate to good yields with excellent diastereoselectivities and generally excellent enantioselectivities (up to >99% enantiomeric excess). This protocol demonstrates Brønsted acid-catalyzed asymmetric dearomatizations via vinylidene-quinone methides.

Copper-Catalyzed Formal Dehydration Polymerization of Propargylic Alcohols via Cumulene Intermediates.

Here we report a copper-catalyzed formal dehydration polymerization of propargylic alcohols. Copper catalysis allows for efficient in situ generation of [n]cumulenes (n = 3, 5) by a soft deprotonation/ß-elimination pathway and subsequent polymerization via organocopper species. Alkyne polymers (Mn up to 36.2 kg/mol) were produced with high efficiency (up to 95% yield) and excellent functional group tolerance. One-pot synthesis of semiconducting head-to-head poly(phenylacetylene) was demonstrated through a polymerization-isomerization sequence.

Stereoselective synthesis of 2,5-disubstituted pyrrolidines via gold-catalysed anti-Markovnikov hydroamination-initiated tandem reactions.

A series of gold-catalysed intramolecular anti-Markovnikov hydroamination-initiated azidation, allylation and heteroarylation reactions of chiral homopropargyl sulfonamides have been developed. Various enantioenriched 2,5-disubstituted pyrrolidines are obtained in moderate to excellent yields with excellent enantioselectivities and generally high diastereoselectivities.