Synthesis of Metabolites and Related Compounds of 3-Isobutyryl-2-isopropylpyrazolo (1,5-a) pyridine (Ibudilast). II. Metabolites of Pyridine Ring.
作者:Katsuya AWANO、Kazuhiko IWASE、Yoshio NAGATSU、Seigo SUZUE
DOI:10.1248/cpb.40.639
日期:——
Novel 6-hydroxylated or methanesulfonylated pyrazolo[1, 5-α]pyridine derivatives as an authentic reference of metabolites for 3-isobutyryl-2-isopropylpyrazolo[1, 5-α]pyridine (ibudilast) were prepared by the method of substitution with Br+ on the pyridine ring and subsequent displacement of Br with MeO- or MeS-. For this reason, we investigated the orientation of halogenation on the pyridine ring of pyrazolo[1, 5-α]pyridine. The reactivity of the pyridine ring was at the 6-position, folowed by the 4-position. We supposed that this finding comes from the electron-donating resonance effect of bridge-head nitrogen. These experimental results were in good agreement with the results of atomic electron densities, but a clear difference was not obtained in those of the Frontier orbitals.
通过 Br+ 取代的方法制备了新型 6-羟基化或甲磺酰化吡唑并[1, 5-α]吡啶衍生物,作为 3-异丁酰-2-异丙基吡唑并[1, 5-α]吡啶(异丁司特)代谢物的可靠参考吡啶环上的 Br 和随后用 MeO- 或 MeS- 取代的 Br。为此,我们研究了吡唑并[1, 5-α]吡啶的吡啶环上卤化的取向。吡啶环的反应活性位于6位,其次是4位。我们推测这一发现来自桥头氮的供电子共振效应。这些实验结果与原子电子密度的结果非常吻合,但前沿轨道的结果没有得到明显的差异。