Tandem intramolecular cyclisation/1,3-aryl shift in N-(4,4-diethoxybutyl)-1-arylmethanimines (Kazan reaction): synthesis of 3-benzylidene-1-pyrrolines

Abstract

A novel tandem reaction, which transforms N-(4,4-diethoxybutyl)imines to 3-arylidene-1-pyrrolines via intramolecular Mannich reaction/[1,3]-sigmatropic rearrangement of the aryl fragment is described.

Acid‐Catalyzed Cascade Reaction of 4‐Aminobutanal Derivatives with (Hetero)aromatic Nucleophiles: A Versatile One‐Pot Access to 2‐(Hetero)arylpyrrolidines.

“…The importance of nucleophilicity‐basicity balance of nitrogen atom in reactions under consideration is demonstrated by behavior of N ‐(4,4‐diethoxybutyl)arylimines 22 in the presence of acids . An interaction of these compounds with various phenols leads to mixtures of unidentified products, whereas in the absence of aromatic nucleophiles they easily undergo intramolecular cyclization to pyrrolidine derivatives 23 .…”

One-Step Synthesis of Functionalized Pyrazolo[3,4-b]pyridines via Ring Opening of the Pyrrolinium Ion

“…We started our work from the study of the reaction of commercially available 3-methyl-1-( p -tolyl)-1 H -pyrazol-5-amine 2a with iminium salt 1a , which is easily accessible according to the known procedure (see Table ). We first performed the reaction at room temperature in chloroform; however, this did not provide the expected result (Table , entry 1).…”

“…These data and our deep interest in the chemistry of 1-pyrrolines , led us to investigate the behavior of N -nucleophiles in this reaction. As a result of our research, herein, we report the synthesis of pyrazolo­[3,4- b ]­pyridines via the reaction of 3-arylidene-1-pyrrolines with aminopyrazole derivatives.…”

Unusual Scaffold Rearrangement in Polyaromatic Hydrocarbons Driven by Concerted Action of Single Gold Atoms on a Gold Surface

“…Transformation of the benzo[c]benzo [6,7]indeno[2,1-c]fluorene scaffold in Precursor to phenanthro(2.1,10,9,8,7-pqrstuv)pentaphene in Moth would formally require an unusual 1,3aryl shift. [45] Another mechanism could be rearrangement by radicalinduced processes similar to those proposed by Kartney et al for the rearrangement of triphenylenes. [46] Following this line of thought, the first step would involve the cleavage of an Csp 2 -Csp 3 bond of the dibenzocyclopentadiene ring resulting in the formation of a biradical.…”