Efficient Synthesis of β-Aryl-γ-lactams and Their Resolution with (S)-Naproxen: Preparation of (R)- and (S)-Baclofen

In Silico Analysis: Anti-Inflammatory and α-Glucosidase Inhibitory Activity of New α-Methylene-γ-Lactams

The research about α-methylene-γ-lactams is scarce; however, their synthesis has emerged in recent years mainly because they are isosters of α-methylene-γ-lactones. This last kind of compound is structurally most common in some natural products' nuclei, like sesquiterpene lactones that show biological activity such as anti-inflammatory, anticancer, antibacterial, etc., effects. In this work, seven α-methylene-γ-lactams were evaluated by their inflammation and α-glucosidase inhibition. Thus, compounds 3-methylene-4-phenylpyrrolidin-2-one (1), 3-methylene-4-(p-tolyl)pyrrolidin-2-one (2), 4-(4-chlorophenyl)-3-methylenepyrrolidin-2-one (3), 4-(2-chlorophenyl)-3-methylenepyrrolidin-2-one (4), 5-ethyl-3-methylene-4-phenylpyrrolidin-2-one (5), 5-ethyl-3-methylene-4-(p-tolyl)pyrrolidin-2-one (6) and 4-(4-chlorophenyl)-5-ethyl-3-methylenepyrrolidin-2-one (7) were evaluated via in vitro α-glucosidase assay at 1 mM concentration. From this analysis, 7 exerts the best inhibitory effect on α-glucosidase compared with the vehicle, but it shows a low potency compared with the reference drug at the same dose. On the other side, inflammation edema was induced using TPA (12-O-tetradecanoylphorbol 13-acetate) on mouse ears; compounds 1-7 were tested at 10 µg/ear dose. As a result, 1, 3, and 5 show a better inhibition than indomethacin, at the same doses. This is a preliminary report about the biological activity of these new α-methylene-γ-lactams.

Maleic Acid as a Co-Former for Pharmaceutically Active GABA Derivatives: Mechanochemistry or Solvent Crystallization?

In this study, we compare the mechanochemical and classical solvent crystallization methods for forming maleates of GABA and its pharmaceutically active derivatives: Pregabalin, Gabapentin, Phenibut, and Baclofen. Common characterization techniques, like powder and single crystal X-ray diffraction, IR-spectroscopy, differential scanning calorimetry, thermogravimetric analysis and ¹H-NMR spectroscopy, are used for the evaluation of structural and physicochemical properties. Our work shows that maleate formation is possible with all investigated target compounds. Large increases in solubility can be achieved, especially for Pregabalin, where up to twentyfold higher solubility in its maleate compared to the pure form can be reached. We furthermore compare the mechanochemical and solvent crystallization regarding quickness, reliability of phase production, and overall product quality. A synthetic route is shown to have an impact on certain properties such as melting point or solubility of the same obtained products, e.g., for Gabapentin and Pregabalin, or lead to the formation of hydrates vs. anhydrous forms. For the GABA and Baclofen maleates, the method of crystallization is not important, and similarly, good results can be obtained by either route. In contrast, Phenibut maleate cannot be obtained pure and single-phase by either method. Our work aims to elucidate promising candidates for the multicomponent crystal formation of blockbuster GABA pharmaceuticals and highlight the usefulness of mechanochemical production routes.

Synthesis, structure, and biological activity of 4-hetaryl-2-pyrrolidones containing a pyrazole ring

Single diastereomers of 4-hetaryl-2-pyrrolidone-3(5)-carbo- and 2-[4-hetaryl-2-pyrrolidon-1-yl]acetohydrazides were used in reactions with 2,4-pentanedione, providing (3R*,4S*)-3-, (4R*,5R*)-5-(3,5-dimethyl-1H-pyrazole-1-carbonyl)- and 1-[2-(3,5-dimethyl-1H-pyrazol-1-yl)-2-oxoethyl]-4-hetaryl-2-pyrrolidones. The structures of the synthesized compounds were confirmed by spectral methods and X-ray structural analysis. Some of the obtained compounds were shown to possess nootropic and anxiolytic activity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10593-022-03140-4.

Catalytic, asymmetric azidations at carbonyls: achiral and meso-anhydride desymmetrisation affords enantioenriched γ-lactams

An unprecedented organocatalytic process involving the asymmetric addition of azide to meso-anhydrides has been developed, promoted by novel sulfamide-substituted Cinchona alkaloid-based catalysts. Readily available glutaric anhydrides can be smoothly converted to enantioenriched hemi-acyl azides and from there to either γ-amino acids or γ-lactams.

Classics in Chemical Neuroscience: Baclofen

Baclofen, β-(4-chlorophenyl)-γ-aminobutyric acid, holds a unique position in neuroscience, remaining the only U.S. Food and Drug Administration (FDA) approved GABA_B agonist. While intended to be a more brain penetrant, i.e, ability to cross the blood-brain barrier (BBB), version of GABA (γ-aminobutyric acid) for the potential treatment of epilepsy, baclofen's highly efficacious muscle relaxant properties led to its approval, as a racemate, for the treatment of spasticity. Interestingly, baclofen received FDA approval before its receptor, GABA_B, was discovered and its exact mechanism of action was known. In recent times, baclofen has a myriad of off-label uses, with the treatment for alcohol abuse and drug addiction garnering a great deal of attention. This Review aims to capture the >60 year legacy of baclofen by walking through the history, pharmacology, synthesis, drug metabolism, routes of administration, and societal impact of this Classic in chemical neuroscience.

Synthesis of New Series of 2-C-(β-D-glucopyranosyl)-Pyrimidines and Their Evaluation as Inhibitors of Some Glycoenzymes

Despite the substantial interest in C-glycosyl heterocycles as mimetics of biologically active native glycans, the appearance of C-glycopyranosyl derivatives of six-membered heterocycles, both in synthetic and biological contexts, is rather scarce. As part of our ongoing research program aimed at preparing hitherto barely known 2-C-glycopyranosyl pyrimidines, the goal of the present study was to synthesize new 5-mono- and multiply substituted derivatives of this compound class. Thus, 2-C-(β-D-glucopyranosyl)-5,6-disubstituted-pyrimidin-4(3H)-ones and 4-amino-2-C-(β-D-glucopyranosyl)-5,6-disubstituted-pyrimidines were prepared by base-mediated cyclocondensations of O-perbenzylated and O-unprotected C-(β-D-glucopyranosyl) formamidine hydrochlorides with methylenemalonic acid derivatives. The 2-C-(β-D-glucopyranosyl)-5-substituted-pyrimidines were obtained from the same amidine precursors upon treatment with vinamidinium salts. The deprotected derivatives of these pyrimidines were tested as inhibitors of some glycoenzymes. None of them showed inhibitory activity towards glycogen phosphorylase and α- and β-glucosidase enzymes, but some members of the sets exhibited moderate inhibition against bovine liver β-galactosidase.

Improving the catalytic efficiency and stereoselectivity of a nitrilase from Synechocystis sp. PCC6803 by semi-rational engineering en route to chiral γ-amino acids

Simultaneously improving activity and stereoselectivity of a nitrilase to catalyze the desymmetrization of 3-substituted glutaronitriles is presented.

Enantio- and Diastereoselective Organocatalytic Conjugate Additions of Nitroalkanes to Enone Diesters

Enantio- and diastereoselective conjugate addition reactions between nitroethane or nitropropane and enone diesters are reported. A bifunctional triaryliminophosphorane catalyzed the addition reaction with consistently excellent stereoselectivities and yields across a wide range of substrates. By the use of the gem-diester functional handle present in the adducts, local desymmetrization via diastereotopic group discrimination was demonstrated, and a polyfunctionalized lactam with three contiguous stereocenters was synthesized.