Silver-catalyzed efficient synthesis of enaminones from propargyl alcohols and amines

The most Recent Compilation of Reactions of Enaminone Derivatives with various Amine Derivatives to Generate Biologically Active Compounds

Heterocyclic derivatives serve as the fundamental components of both natural and synthetic drugs. Enaminones play a crucial role as foundational units in the synthesis of numerous bioactive heterocyclic compounds, including pyrazoles, pyridines, oxazoles, isoxazoles, as well as fused heterocyclic structures like indoles, carbazoles, quinolines, acridines, and phenanthridines. These diverse heterocyclic rings are well-known for their various therapeutic activities, encompassing anticancer, anti-inflammatory, antimicrobial, antidepressant, and antiviral properties. By reacting with nitrogenbased nucleophiles, enaminones can generate bioactive azoles, azines, and their fused systems. This study focuses on the recent advancements in enaminone reactions with (a) nitrogen-based nucleophiles, such as aliphatic amines, derivatives of aniline, heterocyclic amines, hydroxylamine, hydrazine derivatives, guanidine derivatives, urea, and thiourea derivatives, and (b) nitrogen-based electrophiles, such as diazonium salts. These reactions have led to the synthesis of a wide range of bioactive fused heterocyclic compounds from 2010 to the end of 2022.

Synthetic Route to Enaminones via Metal-Free Four-Component Sequential Reactions of Aryl Olefins with CHCl3, Et3N, and TBHP

An efficient and modular strategy was used to obtain enaminones with a wide range of functional groups via a four-component sequential reaction. This reaction proceeded under mild conditions without a catalyst in one pot. Furthermore, the products could be transformed into thiadiazoles.

C3 amino-substituted chalcone derivative with selective adenosine rA1 receptor affinity in the micromolar range

ABSTRACT

To identify novel adenosine receptor (AR) ligands based on the chalcone scaffold, herein the synthesis, characterization and in vitro and in silico evaluation of 33 chalcones (15-36 and 37-41) and structurally related compounds (42-47) are reported. These compounds were characterized by radioligand binding and GTP shift assays to determine the degree and type of binding affinity, respectively, against rat (r) A1 and A2A ARs. The chalcone derivatives 24, 29, 37 and 38 possessed selective A1 affinity below 10 µM, and thus, are the most active compounds of the present series; compound 38 was the most potent selective A1 AR antagonist (K i (r) = 1.6 µM). The structure-affinity relationships (SAR) revealed that the NH2-group at position C3 of ring A of the chalcone scaffold played a key role in affinity, and also, the Br-atom at position C3' on benzylidene ring B. Upon in vitro and in silico evaluation, the novel C3 amino-substituted chalcone derivative 38-that contains an α,ß-unsaturated carbonyl system and easily allows structural modification-may possibly be a synthon in future drug discovery.

GRAPHIC ABSTRACT

C3 amino-substituted chalcone derivative (38) with C3' Br substitution on benzylidene ring B possesses selective adenosine rA1 receptor affinity in micromolar range.

A Method for the Preparation of β-Amino-α,β-unsaturated Carbonyl Compounds: Study of Solvent Effect and Mechanism

An efficient method for the preparation of β-amino-α,β-unsaturated carbonyl compounds is demonstrated. Bench-stable sodium 3-oxo-enolates were prepared from carbonyl compounds, and reacted with amines in the presence of an acid and a desiccant. DFT studies revealed contrasting mechanisms toward the reactivity of aliphatic amines in protic solvents and aromatic amines in aprotic solvents. While the former proceeds through the formation of an imine, the latter passes through the Michael addition-elimination mechanism.