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

Abstract

The title quinolines are obtained as a mixture of products by palladium‐catalyzed intramolecular C—N bond formation and concurrent hydrazine N—N bond fission.

Crystal structure of 1-(4-chlorophenyl)-6,8-diphenyl-1H-pyrazolo[4,3-c]quinoline, C28H18ClN3

“…Pyrazolo [4,3-c]quinoline derivatives serve as photosensitizing anti-cancer agents [7], benzodiazepine antagonists [8], selective cyclooxygenase-2 (COX-2) inhibitors [9] and others exhibit anti-inflammatory properties [6]. Interest in pyrazolo [4,3-c]quinoline-based compounds is (9) 0.0300 (9) not only limited to the synthesis or development of more diverse and complex bioactive derivatives for structureactivity relationship evaluations, but has since been extended to focus on their photophysical properties as potential photosensitizing anti-cancer agents and fluorescence probes.…”

Synthesis of Fused pyrazolo[4,3‐c]quinolines through KI‐Promoted Cyclization of Pyrazole‐arylamines and Benzyl Bromide

“…[6] Alternatively, pyrazole ring is also formed onto a pre-synthesized quinoline scaffold, as an intermediate or starting material. For example, Wang et al has successfully realized the synthesis of 1H-pyrazolo[4,3c]quinolines from 4-chloroquinoline-3-carbaldehydes using palladium as a catalyst, [7] and Subashini and Black et al has reported the formation of pyrazole ring from 4-chloro-3formylquinolin-2[1H]ones and hydrazine. [8] Begtrup's group combined the quinoline moiety into the 1-benzyloxypyrazoles and synthesized a variety of variously substituted pyrazolo[4,3c]quinoline derivatives in one step.…”

“…For example, Wang et al. has successfully realized the synthesis of 1H‐pyrazolo[4,3‐ c ]quinolines from 4‐chloroquinoline‐3‐carbaldehydes using palladium as a catalyst, [7] and Subashini and Black et al. has reported the formation of pyrazole ring from 4‐chloro‐3‐formylquinolin‐2[1H]ones and hydrazine [8] .…”