An Improved Environmentally Friendly Approach to 4-Nitro-, 4-Sulfonyl-, and 4-Aminoquinolines and 4-Quinolones through Conjugate Addition of Nucleophiles to β-(2-Aminophenyl)-α,β-ynones
Sequential addition/annulation reactions of sulfinate and nitrite anions to β-(2-aminophenyl)-α,β-ynones led to valuable 4-sulfonylquinolines and 4-nitroquinolines. The latter proved to be versatile precursors of N-unsubstituted 4-aminoquinolines and 4-quinolones. Reaction of β-(2-aminophenyl)-α,β-ynones with DMF/NaOH resulted in the formation of 4-(dimethylamino)quinolines. The use of an alternative CO-free procedure for the preparation of substrates β-(2-aminophenyl)-α,β-ynones allowed extension of the methodology to the synthesis of 4-substituted 2-alkylquinolines.
The palladium-catalyzed transfer hydrogenation/heterocyclization of β- (2-aminophenyl)-α,β-ynones. An approach to 2-aryl- and 2-vinylquinolines
The palladium-catalyzed transfer hydrogenation/cyclization of readily available β-(o-aminophenyl)-α,β-ynones I affords 2-aryl- and 2- vinylquinolines 3 in good yield.