A facile one-pot synthesis of 2-(2-pyridyl)quinolines via Povarov reaction

First Examples of Povarov Reaction of Cyclopentadienones

“…Inspired by the theoretical studies of the Povarov 's reaction mechanism, these reactions may proceed via a stepwise ion pair mechanism ] where the first step is the electrophilic interaction of the substituted cyclopentadienone with the in situ formed iminium G probably activated by protonation with TFA, which would then undergo ring closure via intramolecular electrophilic attack on the phenyl ring ( Friedel–Crafts ) via a reactive intermediate H, furnishing the desired products 1a , 1b and 2a , 2b ( Scheme ). This hypothesis is supported by Mellor , which has showed that with o ‐phenylenediamine and cyclopentadiene, in similar conditions, a tricyclic amine with a 7‐ring skeleton was formed as by‐product, which proves that mechanism is not concerted …”

“…The Povarov and related aza‐ Diels–Alder reactions have been developed as the most powerful synthetic route for building nitrogen‐containing six‐membered heterocycles . The Povarov reaction can be considered as a formal [4 + 2] cycloaddition of N ‐arylimines, derived from anilines and aromatic aldehydes, with electron‐rich alkenes catalyzed by either protic, lanthanide, or Lewis acids .…”

Recent synthetic efforts in the preparation of 2-(3,4)-alkenyl (aryl) quinoline molecules towards anti-kinetoplastid agents

“…116 In this context, it should be commented that there are still few efficient, direct synthesis for C-4 unsubstituted 2-arylquinolines using 3-C Povarov reaction of anilines, aromatic aldehydes and rich electron alkenes (e.g., alkyl vinyl ethers or N-vinyl amides). [117][118][119][120] that could be a good alternative route to quinolines 65-69.…”

Metal-free domino one-pot protocols for quinoline synthesis

“…Borel et al 69 Quiroga et al, 85 showed that microwave-assisted intramolecular cyclization of N-4-substituted 6-chloropyrimidine-5-carbaldehydes 57 in acetic acid leads to formation of pyrimido [4,5-b]quinolines 56 (deazaavin analogs), which exhibited excellent uorescence properties (Scheme 22). The reaction process involves removal of the both Cl and NH 2 groups of the starting material, as these groups are not present in the nal products.…”