title: Highly stereoselective acid-catalyzed homonucleophilic substitution reactions.
abstract: Enantiomeric 3-O-methyltemazepam and 3-O-ethyltemazepam were highly stereoselectively substituted by the 3-methoxy group of methanol in acidic anhydrous methanol and by the 3-ethoxy group of ethanol in acidic anhydrous ethanol, respectively. The stereoselectivity of the homonucleophilic substitution reactions was determined by circular dichroism spectropolarimetry and gas chromatography-mass spectrometry. In anhydrous solutions containing 0.5 M D2SO4 at 50 degrees C, for example, the stereoselectivity was approximately 63:1 for enantiomeric 3-O-methyltemazepam in CD3OD and approximately 94:1 for enantiomeric 3-O-ethyltemazepam in C2D5OD. The high stereoselectivity at C3 position was primarily due to the presence of a methyl group at N1 position.
authors.affiliation: Department of Pharmacology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Yang
mesh_terms: D000478:Alkylation; D014151:Anti-Anxiety Agents / Q000737:chemistry* / Q000302:isolation & purification*; D002942:Circular Dichroism; D008401:Gas Chromatography-Mass Spectrometry; D008745:Methylation; D015394:Molecular Structure; D013237:Stereoisomerism; D013693:Temazepam / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D014151:Anti-Anxiety Agents; D013693:Temazepam