RESUMEN
The main fragmentation routes of eighteen title compounds and of three 5-chloro derivatives have been investigated with the aid of linked scan (B/E = constant) spectrometry, accurate mass measurements and deuterium labelling. Copyright 1999 John Wiley & Sons, Ltd.
RESUMEN
The chiral oxadiazol-3-one 2 has recently been shown to exhibit myocardial calcium entry channel blocking activity, substantially higher than that of diltiazem. To determine the enantioselectivity of this activity, the enantiomers of 2 have been resolved using chiral chromatography. The absolute configuration (AC) of 2 has been determined by comparison of density functional theory (DFT) calculations of its vibrational circular dichroism (VCD) spectrum, electronic circular dichroism (ECD) spectrum, and optical rotation (OR) to experimental VCD, ECD, and OR data. All three chiroptical properties yield identical ACs; the AC of 2 is unambiguously determined to be S(+)/R(-).
Asunto(s)
Bloqueadores de los Canales de Calcio/química , Oxadiazoles/química , Cromatografía , Dicroismo Circular , Electrones , Modelos Moleculares , Conformación Molecular , Rotación Óptica , Espectrofotometría Infrarroja , Estereoisomerismo , VibraciónRESUMEN
The synthesis of the title compound (4b) has been completed: its rearrangement (in dioxane/water; 1:1, v/v) into N-(2,4-dinitrophenyl)-5-phenyl-2H-1,2,3-triazol-4-ylurea (7) has been quantitatively studied in a wide reactivity (at 293 K, k(A) 10(-8) -4 s(-1)) and pS+ (4.5-14.1) range and compared with that of the Z-2,4-dinitrophenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (10), of the 3-(p-nitro)phenylureine of 5-phenyl-1,2,4-oxadiazole (13), and of N-(5-phenyl-1,2,4-oxadiazol-3-yl)-N'-p-nitrophenylformamidine (14). The results (reactivity, occurrence of specific or general base-catalysis, evidence for or absence of rate-limiting constants) have been well interpreted considering the structure of the side-chains involved and the stability of the final rings obtained in the rearrangements.