Synthesis, biological activity, and absolute stereochemical assignment of NPS 1392: a potent and stereoselective NMDA receptor antagonist

Ni/Photoredox-Catalyzed C(sp3)-C(sp3) Coupling between Aziridines and Acetals as Alcohol-Derived Alkyl Radical Precursors

Aziridines are readily available C(sp³) precursors that afford valuable β-functionalized amines upon ring opening. In this article, we report a Ni/photoredox methodology for C(sp³)-C(sp³) cross-coupling between aziridines and methyl/1°/2° aliphatic alcohols activated as benzaldehyde dialkyl acetals. Orthogonal activation modes of each alkyl coupling partner facilitate cross-selectivity in the C(sp³)-C(sp³) bond-forming reaction: the benzaldehyde dialkyl acetal is activated via hydrogen atom abstraction and β-scission via a bromine radical (generated in situ from single-electron oxidation of bromide), whereas the aziridine is activated at the Ni center via reduction. We demonstrate that an Ni(II) azametallacycle, conventionally proposed in aziridine cross-coupling, is not an intermediate in the productive cross-coupling. Rather, stoichiometric organometallic and linear free energy relationship studies indicate that aziridine activation proceeds via Ni(I) oxidative addition, a previously unexplored elementary step.

Differential influence of 7 cations on 16 non-competitive NMDA receptor blockers

The specific binding of the NMDA receptor (NR) channel ligand [(3)H]MK-801 to rat brain membranes is sensitive to positively charged buffer ingredients as to tris(hydroxymethyl)aminomethane (Tris), to Na(+), or to protons. Here we demonstrate that 16 non-competitive NR antagonists, including 5 long-chain diamines, classical NR channel blockers and several less known compounds, differ widely in their sensitivities to cationic buffer constituents. Although chemically distinguished either as extended di-cationic or as compact mono-cationic, their sensitivities to cationic buffer ingredients did not suggest this grouping. While the di-cationic compounds are known for their sensitivity to spermine (polyamine inverse agonists), also some of the mono-cationic blockers exhibited this feature. They might share as common target a recently described negatively charged extracellular GluN1/GluN2B interface.

Synthesis and Biological Activity of Allosteric Modulators of GABAB Receptors, Part 1. N-(Phenylpropyl)-1-arylethylamines

A series of 15 analogues of fendiline, and 34 derivatives of N-(3-phenylpropyl)-1-arylethylamine have been prepared for evaluation as positive allosteric modulators of GABAB receptors. The most active (EC50, 10 nM) was N-(3,3-diphenylpropyl)-1-(3-chloro-4-methoxyphenyl)ethylamine 6g.

Synthesis and Brain Regional Distribution of [11C]NPS 1506 in Mice and Rat: an N-Methyl-D-aspartate (NMDA) Receptor Antagonist

NPS 1506 [3-fluoro-gamma-(3-fluorophenyl)-N-methylbenzenepropamine] is representative of a non-psychotomimetic class of N-methyl-D-aspartate (NMDA) receptor antagonists. [11C]NPS 1506 was prepared at high radiochemical purity (>98%) with a specific activity of around 50 GBq/micromol at the end of synthesis by methylation of the desmethyl precursor with [11C]methyl iodide in the presence of NaH. Biodistribution of [11C]NPS 1506 in mice and rat demonstrated that uptake into the brain was rapid and occurred at high levels. [11C]NPS 1506 showed no appreciable specific binding in rodent brains under in vivo conditions, possibly because of both a large non-specific bound fraction and low in vitro binding affinity for NMDA receptors.

Chiral synthesis and pharmacological evaluation of NPS 1407: a potent, stereoselective NMDA receptor antagonist

The stereoselective synthesis and biological activity of NPS 1407 (4a), (S)-(-)-3-amino-1,1-bis(3-fluorophenyl)butane, a potent, stereoselective antagonist of the NMDA receptor, are described. The racemate (4) was found to be active at the NMDA receptor in an in vitro assay, prompting the synthesis of the individual stereoisomers. The S isomer (4a) was found to be 12 times more potent than the R isomer (4b). Compound 4a demonstrated in vivo pharmacological activity in neuroprotection and anticonvulsant assays.