John H. Schwerdt

ENANTIOMERIZATION OF AN ATROPISOMERIC DRUG

The antipsoriatic 10-(3-chlorophenyl)-6,8,9,10-tetrahydrobenzo[b][1,8] naphthyridin-5(7H)-one, Sch 40120, is chiral only because it lacks planarity and possesses a stereogenic axis. It comprises short-lived, interconverting atropisomeric enantiomers distinguished by the chlorine substitutent. The atropisomers form diastereomeric complexes with the shift reagent (R)-(−)-2,2,2-trifluoro-1-(9-anthryl)ethanol, which were detected by 1H NMR spectroscopy. Liquid chromatography on an ovomucoid chiral column isolated each enantiomer from the racemic mixture. Re-injections of the separated enantiomers onto the same column held constant at 10°C established that each enantiomer formed the other. Under identical chromatographic conditions, both stereoisomers independently recreated the racemic mixture. The calculated enantiomer half-life lasted 1.6 min at the physiological temperature of 37°C. Simulations of dynamic liquid chromatograms acquired with a chiral stationary phase indirectly yielded values of the half-lives. The chromatograms were modeled with the computer program SIMUL. Also determined were the rate constants for enantiomerization and the corresponding Gibbs free energies of activation, all at varying temperatures. At 37°C, the rate constant and activation energy respectively equaled 0.213 min−1 and 21.6 kcal mole−1. An Arrhenius plot was linear. The intractably brief life spans necessitated development of the racemic drug, rather than advancement of one enantiomer only. The pharmacological, biological, and chemical consequences of molecular asymmetry inherent to the drug were therefore nil.

Intramolecular transaminations of enaminones: a synthesis of fused, polycyclic, N-aryl pyridones

Abstract 2-Arylamino-3-pyridinecarbonyl chlorides acylated the β-carbon atoms of enamines, and the resulting enaminones cyclized to give a series of fused polycyclic N-aryl pyridones. The series included 10-(3-chlorophenyl)-6,8,9,10-tetrahydrobenzo[b][1,8]naphthyridin-5(7H)-one (Sch 40120 ), an antipsoriatic agent.

Synthesis and structure–activity relationships of oxime neurokinin antagonists: discovery of potent arylamides

The structural modification of the benzylic ether region of oxime 1 has resulted in the identification of several novel aryl amides as selective or dual NK(1)/NK(2) antagonists.

Oxidative cleavage of a tricyclic pyridone to a bicyclic lactam-dione

Abstract Two equivalents cf anhydrous m-chloroperbenzoic acid (m-CPBA) cleaved the pyridone ring of 10-(3-chlorophenyl)-6,8,9,10-tetrahydrobenzo[b][1,8]naph forming; the ten-membered lactam α-diketone 12-(3-chlorophenyl)-7,8,9,10-tetrahydropyrido[2,3-b]azecine-5,6,11(12H)-trione. Under aqueous conditions, one equivalent of m-CPBA and the same pyridone formed the lactam α-ketol 12-(3-chlorophenyl)-7,8,9,10-tetrahydro-6-hydroxypyrido[2,3-b]azecine-5,11(6H, 12H)-dio

Base-induced condensation of phenols joined by amides to ketones : a synthesis of hydroxylated isoquinolinones and derivatives

Potassium carbonate in methanol saponified the acetate ester groups of certain meta-acetoxylated α-benzamido ketones and cyclized the resulting phenols in situ to give a series of hydroxylated isoquinolinones and derivatives