Synthesis of N -Fused Seven-Membered Indoline-3-ones via a Palladium-Catalyzed One-Pot Insertion Reaction from 2-Alkynyl Arylazides and Cyclic β -Diketones

Ligand-controlled regiodivergent arylation of aryl(alkyl)alkynes and asymmetric synthesis of axially chiral 9-alkylidene-9,10-dihydroanthracenes

Transition metal-catalyzed addition of organometallics to aryl(alkyl)alkynes has been well known to proceed with the regioselectivity in forming a carbon-carbon bond at the alkyl-substituted carbon (β-addition). Herein, the reverse regiochemistry with high selectivity in giving 1,1-diarylalkenes (α-addition) was realized in the reaction of arylboronic acids with aryl(alkyl)alkynes by use of a rhodium catalyst coordinated with a chiral diene ligand, whereas the arylation of the same alkynes proceeded with the usual regioselectivity (β-addition) in the presence of a rhodium/DM-BINAP catalyst. The regioselectivity can be switched by the choice of ligands on the rhodium catalysts. This reverse regioselectivity also enabled the catalytic asymmetric synthesis of phoenix-like axially chiral alkylidene dihydroanthracenes with high enantioselectivity through an α-addition/1,4-migration/cyclization sequence.

A general approach to 2,2-disubstituted indoxyls: total synthesis of brevianamide A and trigonoliimine C

The indoxyl unit is a common structural motif in alkaloid natural products and bioactive compounds. Here, we report a general method that transforms readily available 2-substituted indoles into 2,2-disubstituted indoxyls via nucleophile coupling with a 2-alkoxyindoxyl intermediate and showcase its utility in short total syntheses of the alkaloids brevianamide A (7 steps) and trigonoliimine C (6 steps). The developed method is operationally simple and demonstrates broad scope in terms of nucleophile identity and indole substitution, tolerating 2-alkyl substituents and free indole N-H groups, elements beyond the scope of most prior approaches. Spirocyclic indoxyl products are also accessible via intramolecular nucleophilic trapping.

Palladium-Catalyzed One-Pot Synthesis of Pyrroloindolines from 2-Alkynyl Arylazides and Thioacetamides

A novel and efficient synthetic method for the preparation of various pyrroloindolines from 2-alkynyl arylazides and thioacetamides was developed. The reaction was carried out in a one-pot process under mild reaction conditions to afford the products in moderate to good yields, which has the potential to be used in organic synthesis.