Enantioenriched Methylene‐Bridged Benzazocanes Synthesis by Organocatalytic and Superacid Activations

Pd-Catalyzed Enantioselective Desymmetrizing 1,7-Enyne Cycloisomerization of Alkyne-Tethered Cyclopentenes

An enantioselective Pd-catalyzed intramolecular desymmetrizing cycloisomerization of N-(cyclopent-3-en-1-yl)propiolamides has been developed by employing a new chiral phosphoramidite ligand. A series of structurally unique bridged azabicycles are achieved in moderate to excellent yields with good E/Z selectivity and high enantioselectivity. Synthetic transformations are conducted to demonstrate the practical utility of this reaction.

Exploring Superacid-Promoted Skeletal Reorganization of Aliphatic Nitrogen-Containing Compounds

Here we report a method to reorganize the core structure of aliphatic unsaturated nitrogen-containing substrates exploiting polyprotonation in superacid solutions. The superelectrophilic activation of N-isopropyl systems allows for the selective formal Csp3 -H activation/cyclization or homologation / functionalization of nitrogen-containing substrates. This study also reveals that this skeletal reorganization can be controlled through protonation interplay. The mechanism of this process involves an original sequence of C-N bond cleavage, isopropyl cation generation and subsequent C-N bond and C-C bond formation. This was demonstrated through in situ NMR analysis and labelling experiments, also confirmed by DFT calculations.

Unbiased C3‐Electrophilic Indoles: Triflic Acid Mediated C3‐Regioselective Hydroarylation of N−H Indoles**

The direct dearomative addition of arenes to the C3 position of unprotected indoles is reported under operationally simple conditions, using triflic acid at room temperature. The present regioselective hydroarylation is a straightforward manner to generate an electrophilic indole at the C3 position from unbiased indoles in sharp contrast to previous strategies. This atom‐economical method delivers biologically relevant 3‐arylindolines and 3,3‐spiroindolines in high yields and regioselectivities from both intra‐ and intermolecular processes. DFT computations suggest the stabilization of cationic or dicationic intermediates with H‐bonded (TfOH)_n clusters.