General and Versatile Entry to 4,5-Fused Polycyclic Imidazolones Systems. Use of the Tandem Transposition/π-Cyclization ofN-Acyliminium Species

Abstract

A simple and efficient methodology for the synthesis of 4,5-fused imidazolidin-2-ones from bicyclic and tricyclic ketones in a four-step sequence was described, by successive spirohydantoin Bucherer-Berg formation, mono- and dialkylation of the nitrogen atom of the hydantoin ring, regioselective reduction of one carbonyl function, and cationic cyclization associated with ring expansion. The key step of this sequential reaction was based on a tandem transposition/intramolecular amidoalkylation of cyclic spiro-N-acyliminium species. The process seems to be easy, general, regiospecific, resulted in the formation of polyheterocyclic systems containing an imidazolidin-2-one nucleus in good to excellent yields (67-99%), and is compatible with a large-scale production (up to 3 g of product 14, for example). Also, this method allows the preparation of the novel heterocycles 14 and 15 that have pharmaceutically interesting profiles, which are not accessible through short current synthetic methods. Finally, products 15 bear a secondary amide function crucial for further transformations, including the introduction of various pharmacophore groups either at the C or the N atoms of the imidazole ring.

A Novel Rearrangement Reaction of N‐Acyliminium Ions Leading to Heterobicycles Arylated at Bridgehead Atom

“…Considering a possible mechanism, intermediate III (Scheme ) could easily eliminate a proton to form an endocyclic C‐C double bond. This assumption is in perfect accordance with reports of similar eliminations after rearrangement .…”

Spectroscopic and theoretical characterization of 2-(4-methoxyphenyl)-4,5-dimethyl-1H-imidazole 3-oxide

“…Imidazole and its derivatives are widely used as intermediates in synthesis of organic target compounds including pharmaceuticals [4][5][6][7][8][9][10], agrochemicals, dyes, photographic chemicals, corrosion inhibitors, epoxy curing agents, adhesives and plastic modifiers [11]. Various biologically active synthetic compounds have five-membered nitrogen-containing heterocyclic ring in their structures [12]. Structural frameworks have been described as privileged structures and in particular, nitrogen containing polycyclic structures has been reported to be associated with a wide range of biological activity [13,14].…”

Synthesis, characterization and spectroscopic studies of novel peripherally tetra-imidazole substituted phthalocyanine and its metal complexes, the computational and experimental studies of the novel phthalonitrile derivative

“…These compound classes are used in many fields such as P38 MAP kinase [28], antivascular disrupting, antitumor activity [29], ionic liquids [30], anion sensors [31], electrical and optical materials [32e34]. Imidazole substituted porphyrines are important structures which are investigated for their optical, electronic and catalytic properties [35e37].…”