Sodium channel binding and anticonvulsant activities for the enantiomers of a bicyclic 2,4-oxazolidinedione and monocyclic models

An efficient computational model to predict protonation at the amide nitrogen and reactivity along the C-N rotational pathway

N-Protonation of amides is critical in numerous biological processes, including amide bonds proteolysis and protein folding as well as in organic synthesis as a method to activate amide bonds towards unconventional reactivity. A computational model enabling prediction of protonation at the amide bond nitrogen atom along the C-N rotational pathway is reported. Notably, this study provides a blueprint for the rational design and application of amides with a controlled degree of rotation in synthetic chemistry and biology.

Medium-bridged lactams: a new class of non-planar amides

Medium-bridged twisted lactams, in which a non-planar amide bond is achieved by incorporating the nitrogen atom at the bridgehead position in a medium-sized heterocycle, offer an attractive setting in which to study the properties of distorted amide linkages. This Emerging Area article will describe progress in the preparation and study of these compounds. This work shows that compounds containing an even moderately distorted amide bond display useful and unusual chemical properties while retaining a measure of stability that enables their study.

Partition coefficients of three new anticonvulsants

The partition coefficients of three homologous anticonvulsant phenylalkylamides [racemic alpha-hydroxy-alpha-ethyl-alpha-phenylacetamide (HEPA); beta-hydroxy-beta-ethyl-beta-phenylpropionamide (HEPP); and gamma-hydroxy-gamma-ethyl-gamma-phenylbutyramide (HEPB)] were determined by reversed-phase high-performance liquid chromatography (RP-HPLC). The system was calibrated with a series of simple amines and amides, using their published log P values. The log kw values (methanol:water, extrapolated to 100% water) were 1.260 for HEPA, 1.670 for HEPP, and 1.852 for HEPB. From these results, the partition coefficients (log P) were calculated by regression as 1.20, 1.83, and 2.11, respectively. The log P values were essentially equal to those calculated by the Leo-Hansch fragmental method. Since the potency of the three anticonvulsants is approximately the same in a variety of tests, no dependence on lipophilicity could be established.

Sodium channel binding and anticonvulsant activities of hydantoins containing conformationally constrained 5-phenyl substituents

As a preliminary investigation of the importance of the aromatic ring orientation in interactions of 5-phenylhydantoins with the anticonvulsant site on the neuronal voltage-sensitive sodium channel, two isomeric hydantoins containing conformationally constrained phenyl rings and their monocyclic analogues were synthesized. One, a spirohydantoin (2) derived from alpha-tetralone, contains the plane of the phenyl ring in an orientation approximately perpendicular to that for the hydantoin ring. The other, a tricyclic hydantoin (4) derived from tetrahydroisoquinoline, contains the plane of the phenyl ring in an orientation roughly coplanar with that for the hydantoin ring. These compounds were evaluated in sodium channel binding and whole animal (mice) anticonvulsant assays. In both assays, 4 was significantly more potent than 2, suggesting that the anticonvulsant receptor site on the voltage-sensitive sodium channel may require a specific aromatic ring orientation.