studied by low-temperature NMR at 500 MHz. Conformational aspects of the carboxonium group in various regioisomers are addressed by a combination of NOED spectra and 2D-NMR and AM1 calculations. Charge delocalization pathways are gauged and compared on the basis of the magnitude of Deltadelta (13)C values.
区域异构的单酰基和单苯甲酰基取代的pyr在FSO(3)H.SbF(5)(4:1)/ SO(2)ClF中被双质子化,以产生持久的car-
吡啶指示,而
二乙酰基和二苯甲酰基-di被二质子化,得到二car适应症。通过在500
MHz下的低温NMR研究所得的指示。通过结合NOED光谱和2D-NMR和
AM1计算,解决了各种区域异构体中碳鎓基团的构象方面。根据Deltadelta(13)C值的大小来度量和比较电荷离域路径。