ABSTRACT
Axially chiral atropisomers have energetic barriers to rotation, ΔGrot, that prevent racemization of the respective enantiomers. We used computational modeling to develop a suite of 10 bio-inspired 1-aryl-ß-carbolines with varying ΔGrot, from which a strong structure-activity relationship was observed for 2-substituted-1-naphthyl substituents. We then synthesized two of these atropisomers, 1d and 1f, by a four-step racemic synthesis and resolved the enantiomers via chiral chromatography. Racemization studies revealed experimental ΔGrot values of 39.5 and 33.0 kcal/mol for 1d and 1f, respectively, which were consistent with our computational results. These atropisomers exhibited long half-lives, which allowed for their physicochemical characterization and stereochemical assignment via UV-vis spectroscopy, fluorescence spectroscopy, electronic circular dichroism, and vibrational circular dichroism.
Subject(s)
Carbolines , Stereoisomerism , Circular Dichroism , Computer Simulation , Spectrometry, FluorescenceABSTRACT
This Article examines the new Emergency Medical Treatment and Labor Act (EMTALA) regulations, focusing on the on-call provisions, in light of the practical realities of the on-call physician shortage. It provides an historical account of issues surrounding the delivery of emergency care by on-call physicians and the legal background of EMTALA insofar as it relates to on-call physicians. Ultimately, the author concludes that, although the current shortage of on-call physicians has caused hospitals to anticipate EMTALA liability and advocate for more specific regulations, a closer look reveals that hospitals' fears are overstated. As long as hospitals have proper procedures in place, the new regulations will not put them in violation of EMTALA.
