Synthesis of 9-arylamino- and (Z)-9-arylimino-9H-pyrrolo[1,2-a]indoles by reactions of 2-(pyrrol-1-yl)benzaldehydes with aryl amines

Synthesis and Some Biological Properties of Pyrrolo[1,2‐a]indoles

“…Otherwise, the reaction does not occur. 9‐Arylaminopyrrolo[1,2‐ a ]indoles 217 were also used from 2‐(pyrrol‐1‐yl)benzaldehydes 214 (R 1 = R 2 = H, R 1 = R 2 = OMe) upon interaction with primary arylamines in the absence of air and solvent under heating up to 90 o С . The same reaction under air leads to ( Z )‐9‐arylamino‐9 Н ‐pyrrolo[1,2‐ a ]indoles 218 .…”

Synthesis and Applications of 9H‐Pyrrolo[1,2‐a]indole and 9H‐Pyrrolo[1,2‐a]indol‐9‐one Derivatives

“…Kobayashi optimized the reaction conditions to selectively isolated either the N ‐aryl‐9 H ‐pyrrolo[1,2‐ a ]indol‐9‐amines 142 (Scheme a) or the corresponding imines 143 (Scheme b), in good isolated yields, starting in both cases from 2‐(1 H ‐pyrrol‐1‐yl)benzaldehydes 141 and arylamines. [50a] The presence of oxygen was necessary for the in situ formation of the imine derivatives. In a second step, the latter products were easily converted into the ketone derivatives in 64–81 % yield (Scheme c).…”

“…An iminium salt was formed in situ and directly cyclized to obtain the desired N , N ‐dialkyl‐9 H ‐pyrrolo[1,2‐ a ]indol‐9‐amines (9 examples, 40–84 % yield). [50b]…”

Palladium‐Catalysed Synthesis of 9H‐Pyrrolo[1,2‐a]indol‐9‐ones and the Isomeric Indeno[2,1‐b]pyrrol‐8‐ones

“…However, this route requires multiple steps, including the transformation of 2‐aminobenzoic acids into 2‐aminobenzoate derivatives, Clauson–Kaas pyrrole synthesis, ester hydrolysis to reveal the free carboxylic acid functionalities (in most cases followed by activation to an acyl chloride), and cyclization. Other less well‐proven methods include the palladium‐catalysed cyclocarbonylation of N ‐(2‐iodophenyl)pyrrole,4 the direct double metallation of N ‐phenylpyrrole followed by treatment of the resulting dilithium salt with ethyl N , N ‐dimethylcarbamate,5 the hydrolysis of 9‐arylimino‐9 H ‐pyrrolo[1,2‐ a ]indoles, which in turn were obtained by the reaction of 2‐(pyrrol‐1‐yl)benzaldehydes with arylamines,6 or the annulation of pyrrole‐2‐carboxylates with benzyne 7…”