New one-step procedure for the synthesis of 6H-chromeno[4,3-b]quinolines and 8a,9,14,14a-tetrahydro-8H-benzo[5,6]chromeno[4,3-b]quinolines

Asymmetric Synthesis of 4‐Amino‐4H‐Chromenes by Organocatalytic Oxa‐Michael/Aza‐Baylis–Hillman Tandem Reactions

“…Their importance is reflected in the existence of dozens of patents related to 4‐aminochromanes bearing different aromatic rings at the NH 2 group 1. Among these compounds, those with a CH 2 OH group at C‐3 (3‐hydroxymethyl‐4‐aminochromanes)2 exhibit interesting biological properties (e.g., antiobiotic),2d and take part in the tetrahydrochromanoquinolines core,3 whereas 1,4 a ‐5,10 b ‐tetrahydro‐4 H ‐chromen4, 3bpyridines are considered as aza analogs of Δ 1 ‐transtetrahydrocannabinols 3hi Moreover, some attractive alkaloids (e.g., martinelli4) with the 4‐aminochromane structure have been described.…”

Efficient three-component synthesis of tetrahydrothieno[3,2-f]quinolines

“…9,23,24 In analogy to the previous results, one should expect to observe the formation of the tetrahydrothienoquinoline. Nevertheless, we obtained the fully aromatized thienoquinoline derivative 4.…”

“…The formation of chromenoquinolines through DielseAlder cycloaddition has also been reported in literature. 23,24 We tried to block this side-reaction by the addition of DMSO or DDQ as oxidizing agents, but this was to no avail. We briefly studied the possibility to convert the synthesized tetrahydrothienoquinoline into the fully aromatic thienoquinoline (Scheme 2B).…”

Copper-Catalyzed Aza-Diels–Alder Reaction and Halogenation: An Approach To Synthesize 7-Halogenated Chromenoquinolines

“…Moreover, 7-chloro-6 H -chromenoquinolines and 7-bromo-6 H -chromenoquinolines are utilized as intermediates to synthesize various substituted chromenoquinolines through transition-metal-catalyzed cross-coupling reactions. Although chromenoquinolines can be easily synthesized through aza-Diels–Alder reaction, − the synthesis of 7-halogenated chromenoquinolines, such as 7-chloro-6 H -chromeno­[4,3- b ]­quinoline and 7-bromo-6 H -chromeno­[4,3- b ]­quinoline, is difficult. In 2007, Vu et al synthesized 7-chloro-6 H -chromeno­[4,3- b ]­quinolines and 7-bromo-6 H -chromeno­[4,3- b ]­quinolines for the first time (Scheme ).…”