Catalyst-controlled cascade synthesis of bridged bicyclic tetrahydrobenz[b]azepine-4-ones.

A catalyst-controlled cascade reaction has been developed for the synthesis of bridged bicyclic tetrahydrobenz[b]azepin-4-ones from N-arylnitrones and allenes. This method expands the accessible structural diversity of a synthetically challenging heterocyclic scaffold and tunes a catalyst-sensitive process in a new direction.

Catalytic Asymmetric Synthesis of Dihydropyrido[1,2-a]indoles from Nitrones and Allenoates.

An asymmetric method for the synthesis of dihydropyrido[1,2-a]indoles from mixtures of nitrones and allenoates has been developed. This transformation showcases the use of squaramide catalysis in a complicated cascade system that has been shown to be highly sensitive to reaction conditions and substituent effects. The new method provides access to enantiomerically enriched dihydropyridoindoles from modular, non-indole reagents.

Copper-mediated synthesis of N-alkenyl-α,β-unsaturated nitrones and their conversion to tri- and tetrasubstituted pyridines.

A Chan-Lam reaction has been used to prepare N-alkenyl-α,β-unsaturated nitrones, which undergo a subsequent thermal rearrangement to the corresponding tri- and tetrasubstituted pyridines. The optimization and scope of these transformations is discussed. Initial mechanistic experiments suggest a reaction pathway involving oxygen transfer followed by cyclization.