Synthesis of Bridged Tetrahydrobenzo[ b ]azepines and Derivatives through an Aza‐Piancatelli Cyclization/Michael Addition Sequence

Unified Approach to Diverse Fused Fragments via Catalytic Dehydrative Cyclization

A range of highly functionalized polycyclic fragments have been synthesized, employing a catalytic dehydrative cyclization. A range of nucleophiles are shown to be successful, with the reaction producing numerous high value motifs.

Sigmatropic [1,5] Carbon Shift of Transient C3 Ammonium Enolates

The stereospecific sigmatropic [1,5] carbon shift of C3 ammonium enolates is discovered. According to mechanistic, kinetic and computational experiments, this new rearrangement proceeds via the catalytic generation of a transient C3 ammonium enolate by intramolecular aza-Michael addition. This intermediate rapidly undergoes [1,5] sigmatropic carbon migration to furnish the respective tetrahydroquinoline-4-ones with excellent diastereoselectivities of d.r. >99 : 1 and in 61-98 % yield.

Unprecedented Reactivity of γ-Amino Cyclopentenone Enables Diversity-Oriented Access to Functionalized Indoles and Indole-Annulated Ring Structures

Observation of an unexpected, Lewis acid promoted displacement of latent reactive γ-amino group on cyclopentenone presented unparalleled opportunity for enone functionalization and annulations with indole derivatives, which is developed in the current study. Herein, a vast range of C3/N-indolyl enones and indole alkaloid-like compound were accessed in excellent yields (up to 99 %) and selectivity through a one-pot operation. The mechanism most likely involves an unprecedented trait of Piancatelli-type rearrangement where influence of the gem-diaryl group appeared crucial.