Efficient synthesis of functionalized dihydroquinolines, quinolines and dihydrobenzo[b]azepine via an iron(III) chloride-catalyzed intramolecular alkyne-carbonyl metathesis of alkyne tethered 2-amino benzaldehyde/acetophenone derivatives.
In this study we have developed an efficient synthesis of 1,2-dihydroquinoline and dihydrobenzo[b]azepine derivatives involving the iron(III) chloride intramolecular alkyne-carbonyl metathesis reaction for the first time. Various functionalized 1,2-dihydroquinolines and dihydrobenzo[b]azepines were prepared from easily accessible substrates in the presence of environmentally friendly and inexpensive iron(III) chloride (10 mol%) under mild conditions. The method is applicable to a wide range of substrates containing different functional groups and furnishing products in good to excellent yields. This methodology was further extended to the one-pot synthesis of 3-acyl quinolines via alkyne-carbonyl metathesis/detosylation/aromatization of N-propargyl-2-aminobenzaldehyde/acetophenone derivatives by the addition of NaOH/EtOH. While many Lewis acid and Brønsted acid catalysts were investigated, anhydrous iron(III) chloride turned out to be the best catalyst for this transformation.
Department of Chemistry, Jadavpur University, Kolkata-700 032, West Bengal, India. jumasish2004@yahoo.co.in.
Swapnadeep
S
Jalal
Krishnendu
K
Bera
Soumen
S
Sarkar
Kartick
K
Paul
Umasish
U
Jana
D000098:Acetophenones / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry*; D001381:Azepines / Q000138:chemical synthesis* / Q000737:chemistry; D001547:Benzaldehydes / Q000737:chemistry*; D002384:Catalysis; D005290:Ferric Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D011804:Quinolines / Q000138:chemical synthesis* / Q000737:chemistry
D000098:Acetophenones; D000480:Alkynes; D001381:Azepines; D001547:Benzaldehydes; D005290:Ferric Compounds; D011804:Quinolines; C000062:2-aminobenzaldehyde; C055495:2-aminoacetophenone