Synthesis of novel ferrocenyl-containing pyrazolo[4,3-c]quinolines

Construction of substituted pyrazolo[4,3‐c]quinolines via [5+1] cyclization of pyrazole‐arylamines with alcohols/amines in one pot

“…Recently, Nagarapu and co‐workers reported the synthesis of pyrazolo[4,3‐c]quinoline by the condensation of 2‐(1 H ‐pyrazol‐5‐yl)aniline and aldehydes in the presence of molecular iodine [10]. Cin and co‐workers described the synthesis of ferrocenyl‐containing pyrazolo[4,3‐c]quinolines by reaction of the (1 H ‐pyrazol‐5‐yl)anilines with ferrocenecarboxaldehyde under Pictet–Spengler conditions via iminium intermediate, which undergoes endocyclization in the acidic medium [11]. According to these findings, the amine derivatives can react with either ketones or aldehydes to generate the corresponding ketimines/aldimines, followed by carbon‐centered radical cyclization under acidic conditions.…”

Copper triflate-mediated synthesis of 1,3,5-triarylpyrazoles in [bmim][PF6] ionic liquid and evaluation of their anticancer activities

“…However, this strategy results in the formation of 4,5-dihydro-1 H -pyrazoles (pyrazolines) that need to be further oxidized to corresponding pyrazoles. For this oxidative aromatization of pyrazolines to pyrazoles, various reagents have been employed such as I 2 , 17 Bi(NO 3 ) 3 .5H 2 O, 18 MnO 2 , 19 DDQ, 20 Pd/C, 21 NaOEt, 22 PhI(OAc) 2 , 23 TBBDA, 24 and ionic liquid. 25, 26 However, many of these oxidative methods suffer from relatively high oxidant loading, use of strong oxidants and chlorinated organic solvents, harsh conditions, poor yields, and longer reaction time.…”

Palladium-Catalyzed Synthesis of 1H-Pyrazolo[4,3-c]quinolines and 4-Anilinoquinoline-3-carbonitriles from 4-Chloroquinoline-3-carbaldehydes

“…8 Novel ferrocenyl-containing pyrazolo [4,3-c]quinolines have been synthesized by the Pictet-Spengler reaction. 9 A wide range of target-directed and diversity-oriented efforts have been devoted to the synthesis of pyrazolo [4,3c]quinolines. 8,10 Several approaches are available for the synthesis of pyrazolo [4,3-c]quinolines, and these can be classified into two main categories: annulation of the pyra-zole ring onto a quinoline scaffold or annulation of the quinoline ring onto a pyrazole scaffold.…”